751 lines
30 KiB
C
751 lines
30 KiB
C
/*
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out123: audio output interface
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copyright 1995-2016 by the mpg123 project,
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free software under the terms of the LGPL 2.1
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see COPYING and AUTHORS files in distribution or http://mpg123.org
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initially written as audio.h by Michael Hipp, reworked into out123 API
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by Thomas Orgis
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*/
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#ifndef _OUT123_H_
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#define _OUT123_H_
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/** \file out123.h The header file for the libout123 audio output facility. */
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/** A macro to check at compile time which set of API functions to expect.
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* This must be incremented at least each time a new symbol is added
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* to the header.
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*/
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#define OUT123_API_VERSION 5
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/** library patch level at client build time */
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#define OUT123_PATCHLEVEL 1
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/* We only need size_t definition. */
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#include <stddef.h>
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/* Common audio encoding specification, including a macro for getting
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* size of encoded samples in bytes. Said macro is still hardcoded
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* into out123_encsize(). Relying on this one may help an old program
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* know sizes of encodings added to fmt123.h later on.
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* If you don't care, just use the macro.
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*/
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#include "fmt123.h"
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#ifndef MPG123_EXPORT
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/** Defines needed for MS Visual Studio(tm) DLL builds.
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* Every public function must be prefixed with MPG123_EXPORT. When building
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* the DLL ensure to define BUILD_MPG123_DLL. This makes the function accessible
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* for clients and includes it in the import library which is created together
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* with the DLL. When consuming the DLL ensure to define LINK_MPG123_DLL which
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* imports the functions from the DLL.
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*/
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#ifdef BUILD_MPG123_DLL
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/* The dll exports. */
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#define MPG123_EXPORT __declspec(dllexport)
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#else
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#ifdef LINK_MPG123_DLL
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/* The exe imports. */
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#define MPG123_EXPORT __declspec(dllimport)
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#else
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/* Nothing on normal/UNIX builds */
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#define MPG123_EXPORT
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#endif
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#endif
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#endif
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/* Earlier versions of libout123 put enums into public API calls,
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* thich is not exactly safe. There are ABI rules, but you can use
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* compiler switches to change the sizes of enums. It is safer not
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* to have them in API calls. Thus, the default is to remap calls and
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* structs to variants that use plain ints. Define MPG123_ENUM_API to
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* prevent that remapping.
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*
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* You might want to define this to increase the chance of your binary
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* working with an older version of the library. But if that is your goal,
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* you should better build with an older version to begin with.
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*/
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#ifndef MPG123_ENUM_API
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#define out123_param out123_param2
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#define out123_getparam out123_getparam2
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** \defgroup out123_api out123 library API
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* This is out123, a library focused on continuous playback of audio streams
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* via various platform-specific output methods. It glosses over details of
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* the native APIs to give an interface close to simply writing data to a
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* file. There might be the option to tune details like buffer (period) sizes
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* and the number of them on the device side in future, but the focus of the
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* library is to ease the use case of just getting that raw audio data out
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* there, without interruptions.
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*
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* The basic idea is to create a handle with out123_new() and open a certain
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* output device (using a certain driver module, possibly build-time defaults)
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* with out123_open(). Now, you can query the output device for supported
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* encodings for given rate and channel count with out123_get_encodings() and
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* decide what to use for actually starting playback with out123_start().
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*
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* Then, you just need to provide (interleaved pcm) data for playback with
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* out123_play(), which will block when the device's buffers are full. You get
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* your timing from that (instead of callbacks). If your program does the
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* production of the audio data just a little bit faster than the playback,
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* causing out123_play() to block ever so briefly, you're fine.
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*
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* You stop playback with out123_stop(), or just close the device and driver
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* via out123_close(), or even just decide to drop it all and do out123_del()
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* right away when you're done.
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*
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* There are other functions for specific needs, but the basic idea should be
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* covered by the above.
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*
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* Note that the driver modules that bind to the operating system API for
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* output might impose restrictions on what you can safely do regarding your
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* out123_handle and multiple threads or processes. You should be on the safe
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* side ensuring that you confine usage of a handle to a single thread instead
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* of passing it around.
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@{
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*/
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/** Opaque structure for the libout123 handle. */
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struct out123_struct;
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/** Typedef shortcut as preferrend name for the handle type. */
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typedef struct out123_struct out123_handle;
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/** Get version of the mpg123 distribution this library build came with.
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* (optional means non-NULL)
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* \param major optional address to store major version number
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* \param minor optional address to store minor version number
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* \param patch optional address to store patchlevel version number
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* \return full version string (like "1.2.3-beta4 (experimental)")
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*/
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MPG123_EXPORT
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const char *out123_distversion(unsigned int *major, unsigned int *minor, unsigned int *patch);
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/** Get API version of library build.
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* \param patch optional address to store patchlevel
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* \return API version of library
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*/
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MPG123_EXPORT
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unsigned int out123_libversion(unsigned int *patch);
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/** Enumeration of codes for the parameters that it is possible to set/get. */
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enum out123_parms
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{
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OUT123_FLAGS = 1 /**< integer, various flags, see enum #out123_flags */
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, OUT123_PRELOAD /**< float, fraction of buffer to fill before playback */
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, OUT123_GAIN /**< integer, output device gain (module-specific) */
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, OUT123_VERBOSE /**< integer, verbosity to stderr, >= 0 */
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, OUT123_DEVICEBUFFER /**<
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* float, length of device buffer in seconds;
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* This might be ignored, might have only a loose relation to actual
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* buffer sizes and latency, depending on output driver. Try to tune
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* this before opening a device if you want to influcence latency or reduce
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* dropouts. Value <= 0 uses some default, usually favouring stable playback
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* over low latency. Values above 0.5 are probably too much.
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*/
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, OUT123_PROPFLAGS /**< integer, query driver/device property flags (r/o) */
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, OUT123_NAME /**< string, name of this instance (NULL restores default);
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* The value returned by out123_getparam() might be different if the audio
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* backend changed it (to be unique among clients, p.ex.).
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* TODO: The name provided here is used as prefix in diagnostic messages. */
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, OUT123_BINDIR /**< string, path to a program binary directory to use
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* as starting point in the search for the output module directory
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* (e.g. ../lib/mpg123 or ./plugins). The environment variable MPG123_MODDIR
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* is always tried first and the in-built installation path last.
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*/
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, OUT123_ADD_FLAGS /**< enable given flags */
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, OUT123_REMOVE_FLAGS /**< disable diven flags */
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};
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/** Flags to tune out123 behaviour */
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enum out123_flags
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{
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OUT123_HEADPHONES = 0x01 /**< output to headphones (if supported) */
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, OUT123_INTERNAL_SPEAKER = 0x02 /**< output to speaker (if supported) */
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, OUT123_LINE_OUT = 0x04 /**< output to line out (if supported) */
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, OUT123_QUIET = 0x08 /**< no printouts to standard error */
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, OUT123_KEEP_PLAYING = 0x10 /**<
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* When this is set (default), playback continues in a loop when the device
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* does not consume all given data at once. This happens when encountering
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* signals (like SIGSTOP, SIGCONT) that cause interruption of the underlying
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* functions.
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* Note that this flag is meaningless when the optional buffer is employed,
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* There, your program will always block until the buffer completely took
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* over the data given to it via out123_play(), unless a communication error
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* arises.
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*/
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, OUT123_MUTE = 0x20 /**< software mute (play silent audio) */
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};
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/** Read-only output driver/device property flags (OUT123_PROPFLAGS). */
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enum out123_propflags
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{
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OUT123_PROP_LIVE = 0x01 /**< This is a live output, meaning that
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* special care might be needed for pauses in playback (p.ex. stream
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* of silence instead of interruption), as opposed to files on disk.
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*/
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, OUT123_PROP_PERSISTENT = 0x02 /**< This (live) output does not need
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* special care for pauses (continues with silence itself),
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* out123_pause() does nothing to the device.
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*/
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};
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/** Create a new output handle.
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* This only allocates and initializes memory, so the only possible
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* error condition is running out of memory.
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* \return pointer to new handle or NULL on error
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*/
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MPG123_EXPORT
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out123_handle *out123_new(void);
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/** Delete output handle.
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* This implies out123_close().
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*/
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MPG123_EXPORT
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void out123_del(out123_handle *ao);
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/** Free plain memory allocated within libout123.
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* This is for library users that are not sure to use the same underlying
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* memory allocator as libout123. It is just a wrapper over free() in
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* the underlying C library.
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*/
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MPG123_EXPORT void out123_free(void *ptr);
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/** Error code enumeration
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* API calls return a useful (positve) value or zero (OUT123_OK) on simple
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* success. A negative value (-1 == OUT123_ERR) usually indicates that some
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* error occured. Which one, that can be queried using out123_errcode()
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* and friends.
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*/
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enum out123_error
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{
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OUT123_ERR = -1 /**< generic alias for verbosity, always == -1 */
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, OUT123_OK = 0 /**< just a name for zero, not going to change */
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, OUT123_DOOM /**< dazzled, out of memory */
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, OUT123_BAD_DRIVER_NAME /**< bad driver name given */
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, OUT123_BAD_DRIVER /**< unspecified issue loading a driver */
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, OUT123_NO_DRIVER /**< no driver loaded */
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, OUT123_NOT_LIVE /**< no active audio device */
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, OUT123_DEV_PLAY /**< some device playback error */
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, OUT123_DEV_OPEN /**< error opening device */
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, OUT123_BUFFER_ERROR /**<
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* Some (really unexpected) error in buffer infrastructure.
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*/
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, OUT123_MODULE_ERROR /**< basic failure in module loading */
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, OUT123_ARG_ERROR /**< some bad function arguments supplied */
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, OUT123_BAD_PARAM /**< unknown parameter code */
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, OUT123_SET_RO_PARAM /**< attempt to set read-only parameter */
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, OUT123_BAD_HANDLE /**< bad handle pointer (NULL, usually) */
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, OUT123_NOT_SUPPORTED /**< some requested operation is not supported (right now) */
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, OUT123_DEV_ENUMERATE /**< device enumeration itself failed */
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, OUT123_ERRCOUNT /**< placeholder for shaping arrays */
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};
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/** Get string representation of last encountered error in the
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* context of given handle.
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* \param ao handle
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* \return error string
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*/
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MPG123_EXPORT
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const char* out123_strerror(out123_handle *ao);
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/** Get the plain errcode intead of a string.
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* Note that this used to return OUT123_ERR instead of
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* OUT123_BAD_HANDLE in case of ao==NULL before mpg123-1.23.5 .
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* \param ao handle
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* \return error code recorded in handle or OUT123_BAD_HANDLE
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*/
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MPG123_EXPORT
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int out123_errcode(out123_handle *ao);
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/** Return the error string for a given error code.
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* \param errcode the integer error code
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* \return error string
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*/
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MPG123_EXPORT
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const char* out123_plain_strerror(int errcode);
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/** Set a desired output buffer size.
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* This starts a separate process that handles the audio output, decoupling
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* the latter from the main process with a memory buffer and saving you the
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* burden to ensure sparing CPU cycles for actual playback.
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* This is for applicatons that prefer continuous playback over small latency.
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* In other words: The kind of applications that out123 is designed for.
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* This routine always kills off any currently active audio output module /
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* device, even if you just disable the buffer when there is no buffer.
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*
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* Keep this in mind for memory-constrainted systems: Activating the
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* buffer causes a fork of the calling process, doubling the virtual memory
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* use. Depending on your operating system kernel's behaviour regarding
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* memory overcommit, it might be wise to call out123_set_buffer() very
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* early in your program before allocating lots of memory.
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*
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* There _might_ be a change to threads in future, but for now this is
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* classic fork with shared memory, working without any threading library.
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* If your platform or build does not support that, you will always get an
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* error on trying to set up a non-zero buffer (but the API call will be
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* present).
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*
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* Also, if you do intend to use this from a multithreaded program, think
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* twice and make sure that your setup is happy with forking full-blown
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* processes off threaded programs. Probably you are better off spawning a
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* buffer thread yourself.
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*
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* \param ao handle
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* \param buffer_bytes size (bytes) of a memory buffer for decoded audio,
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* a value of zero disables the buffer.
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* \return 0 on success, OUT123_ERR on error
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*/
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MPG123_EXPORT
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int out123_set_buffer(out123_handle *ao, size_t buffer_bytes);
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#ifdef MPG123_ENUM_API
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/** Set a parameter on a out123_handle.
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*
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* Note that this name is mapped to out123_param2() instead unless
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* MPG123_ENUM_API is defined.
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*
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* The parameters usually only change what happens on next out123_open, not
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* incfluencing running operation. There are macros To ease the API a bit:
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* You can call out123_param_int(ao, code, value) for integer (long) values,
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* same with out123_param_float() and out123_param_string().
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*
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* \param ao handle
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* \param code parameter code
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* \param value input value for integer parameters
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* \param fvalue input value for floating point parameters
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* \param svalue input value for string parameters (contens are copied)
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* \return 0 on success, OUT123_ERR on error.
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*/
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MPG123_EXPORT
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int out123_param( out123_handle *ao, enum out123_parms code
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, long value, double fvalue, const char *svalue );
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#endif
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/** Set a parameter on a out123_handle. No enum.
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*
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* This is actually called instead of out123_param()
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* unless MPG123_ENUM_API is defined.
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*
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* The parameters usually only change what happens on next out123_open, not
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* incfluencing running operation. There are macros To ease the API a bit:
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* You can call out123_param_int(ao, code, value) for integer (long) values,
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* same with out123_param_float() and out123_param_string().
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*
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* \param ao handle
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* \param code parameter code (from enum #out123_parms)
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* \param value input value for integer parameters
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* \param fvalue input value for floating point parameters
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* \param svalue input value for string parameters (contens are copied)
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* \return 0 on success, OUT123_ERR on error.
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*/
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MPG123_EXPORT
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int out123_param2( out123_handle *ao, int code
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, long value, double fvalue, const char *svalue );
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/** Shortcut for out123_param() to set an integer parameter. */
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#define out123_param_int(ao, code, value) \
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out123_param((ao), (code), (value), 0., NULL)
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/** Shortcut for out123_param() to set a float parameter. */
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#define out123_param_float(ao, code, value) \
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out123_param((ao), (code), 0, (value), NULL)
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/** Shortcut for out123_param() to set an string parameter. */
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#define out123_param_string(ao, code, value) \
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out123_param((ao), (code), 0, 0., (value))
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#ifdef MPG123_ENUM_API
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/** Get a parameter from an out123_handle.
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*
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* Note that this name is mapped to out123_param2() instead unless
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* MPG123_ENUM_API is defined.
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*
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* \param ao handle
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* \param code parameter code
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* \param ret_value output address for integer parameters
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* \param ret_fvalue output address for floating point parameters
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* \param ret_svalue output address for string parameters (pointer to
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* internal memory, so no messing around, please)
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* \return 0 on success, OUT123_ERR on error (bad parameter name or bad handle).
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*/
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MPG123_EXPORT
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int out123_getparam( out123_handle *ao, enum out123_parms code
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, long *ret_value, double *ret_fvalue, char* *ret_svalue );
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#endif
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/** Get a parameter from an out123_handle. No enum.
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*
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* This is actually called instead of out123_getparam()
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* unless MPG123_ENUM_API is defined.
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*
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* \param ao handle
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* \param code parameter code (from enum #out123_parms)
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* \param ret_value output address for integer parameters
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* \param ret_fvalue output address for floating point parameters
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* \param ret_svalue output address for string parameters (pointer to
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* internal memory, so no messing around, please)
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* \return 0 on success, OUT123_ERR on error (bad parameter name or bad handle).
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*/
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MPG123_EXPORT
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int out123_getparam2( out123_handle *ao, int code
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, long *ret_value, double *ret_fvalue, char* *ret_svalue );
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/** Shortcut for out123_getparam() to get an integer parameter. */
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#define out123_getparam_int(ao, code, value) \
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out123_getparam((ao), (code), (value), NULL, NULL)
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/** Shortcut for out123_getparam() to get a float parameter. */
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#define out123_getparam_float(ao, code, value) \
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out123_getparam((ao), (code), NULL, (value), NULL)
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/** Shortcut for out123_getparam() to get a string parameter. */
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#define out123_getparam_string(ao, code, value) \
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out123_getparam((ao), (code), NULL, NULL, (value))
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/** Copy parameters from another out123_handle.
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* \param ao handle
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* \param from_ao the handle to copy parameters from
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* \return 0 in success, -1 on error
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*/
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MPG123_EXPORT
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int out123_param_from(out123_handle *ao, out123_handle* from_ao);
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/** Get list of driver modules reachable in system in C argv-style format.
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*
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* The client is responsible for freeing the memory of both the individual
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* strings and the lists themselves. There is out123_stringlists_free()
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* to assist.
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*
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* A module that is not loadable because of missing libraries is simply
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* skipped. You will get stderr messages about that unless OUT123_QUIET was
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* was set, though. Failure to open the module directory is a serious error,
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* resulting in negative return value.
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*
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* \param ao handle
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* \param names address for storing list of names
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* \param descr address for storing list of descriptions
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* \return number of drivers found, -1 on error
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*/
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MPG123_EXPORT
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int out123_drivers(out123_handle *ao, char ***names, char ***descr);
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/** Get a list of available output devices for a given driver.
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*
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* If the driver supports enumeration, you can get a listing of possible
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* output devices. If this list is exhaustive, depends on the driver.
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* Note that this implies out123_close(). When you have a device already
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* open, you don't need to look for one anymore. If you really do, just
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* create another handle.
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*
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* Your provided pointers are only used for non-negative return values.
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* In this case, you are responsible for freeing the associated memory of
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* the strings and the lists themselves. The format of the lists is an
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* array of char pointers, with the returned count just like the usual
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* C argv and argc. There is out123_stringlists_free() to assist.
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*
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* Note: Calling this on a handle with a configured buffer process will
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* yield #OUT123_NOT_SUPPORTED.
|
|
*
|
|
* \param ao handle
|
|
* \param driver driver name or comma-separated list of names
|
|
* to try, just like for out123_open(), possibly NULL for some default
|
|
* \param names address for storing list of names
|
|
* \param descr address for storing list of descriptions
|
|
* \param active_driver address for storing a copy of the actually active
|
|
* driver name (in case you gave a list or NULL as driver), can be NULL
|
|
* if not interesting
|
|
* \return count of devices or #OUT123_ERR if some error was encountered,
|
|
* possibly just #OUT123_NOT_SUPPORTED if the driver lacks enumeration support
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_devices( out123_handle *ao, const char *driver
|
|
, char ***names, char ***descr, char **active_driver );
|
|
|
|
/** Helper to free string list memory.
|
|
*
|
|
* This aids in freeing the memory allocated by out123_devices() and
|
|
* out123_drivers().
|
|
*
|
|
* Any of the given lists can be NULL and nothing will happen to it.
|
|
*
|
|
* \param name first string list
|
|
* \param descr second string list
|
|
* \param count count of strings
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_stringlists_free(char **name, char **descr, int count);
|
|
|
|
|
|
/** Open an output device with a certain driver
|
|
* Note: Opening means that the driver code is loaded and the desired
|
|
* device name recorded, possibly tested for availability or tentatively
|
|
* opened. After out123_open(), you can ask for supported encodings
|
|
* and then really open the device for playback with out123_start().
|
|
* \param ao handle
|
|
* \param driver (comma-separated list of) output driver name(s to try),
|
|
* NULL for default
|
|
* \param device device name to open, NULL for default
|
|
* (stdout for file-based drivers)
|
|
* \return 0 on success, -1 on error.
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_open(out123_handle *ao, const char* driver, const char* device);
|
|
|
|
/** Give info about currently loaded driver and device
|
|
* Any of the return addresses can be NULL if you are not interested in
|
|
* everything. You get pointers to internal storage. They are valid
|
|
* as long as the driver/device combination is opened.
|
|
* The device may be NULL indicating some unnamed default.
|
|
* TODO: Make the driver modules return names for such defaults.
|
|
* \param ao handle
|
|
* \param driver return address for driver name
|
|
* \param device return address for device name
|
|
* \return 0 on success, -1 on error (i.e. no driver loaded)
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_driver_info(out123_handle *ao, char **driver, char **device);
|
|
|
|
/** Close the current output device and driver.
|
|
* This implies out123_drain() to ensure no data is lost.
|
|
* With a buffer, that might cause considerable delay during
|
|
* which your main application is blocked waiting.
|
|
* Call out123_drop() beforehand if you want to end things
|
|
* quickly.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_close(out123_handle *ao);
|
|
|
|
/** Get supported audio encodings for given rate and channel count,
|
|
* for the currently openend audio device.
|
|
* Usually, a wider range of rates is supported, but the number
|
|
* of sample encodings is limited, as is the number of channels.
|
|
* So you can call this with some standard rate and hope that the
|
|
* returned encodings work also for others, with the tested channel
|
|
* count.
|
|
* The return value of -1 on some encountered error conveniently also
|
|
* does not match any defined format (only 15 bits used for encodings,
|
|
* so this would even work with 16 bit integers).
|
|
* This implies out123_stop() to enter query mode.
|
|
* \param ao handle
|
|
* \param rate sampling rate
|
|
* \param channels number of channels
|
|
* \return supported encodings combined with bitwise or, to be checked
|
|
* against your favourite bitmask, -1 on error
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_encodings(out123_handle *ao, long rate, int channels);
|
|
|
|
/** Return the size (in bytes) of one mono sample of the named encoding.
|
|
* \param encoding The encoding value to analyze.
|
|
* \return positive size of encoding in bytes, 0 on invalid encoding. */
|
|
MPG123_EXPORT int out123_encsize(int encoding);
|
|
|
|
/** Get list of supported formats for currently opened audio device.
|
|
* Given a list of sampling rates and minimal/maximal channel count,
|
|
* this quickly checks what formats are supported with these
|
|
* constraints. The first entry is always reserved for a default
|
|
* format for the output device. If there is no such default,
|
|
* all values of the format are -1.
|
|
* For each requested combination of rate and channels, a format entry is
|
|
* created, possible with encoding value 0 to indicate that this combination
|
|
* has been tested and rejected. So, when there is no basic error, the
|
|
* number of returned format entries should be
|
|
* (ratecount*(maxchannels-minchannels+1)+1)
|
|
* . But instead of forcing you to guess, this will be allocated by
|
|
* successful run.
|
|
* For the first entry, the encoding member is supposed to be a definite
|
|
* encoding, for the others it is a bitwise combination of all possible
|
|
* encodings.
|
|
* This function is more efficient than many calls to out123_encodings().
|
|
* \param ao handle
|
|
* \param rates pointer to an array of sampling rates, may be NULL for none
|
|
* \param ratecount number of provided sampling rates
|
|
* \param minchannels minimal channel count
|
|
* \param maxchannels maximal channel count
|
|
* \param fmtlist return address for array of supported formats
|
|
* the encoding field of each entry is a combination of all
|
|
* supported encodings at this rate and channel count;
|
|
* Memory shall be freed by user.
|
|
* \return number of returned format enries, -1 on error
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_formats( out123_handle *ao, const long *rates, int ratecount
|
|
, int minchannels, int maxchannels
|
|
, struct mpg123_fmt **fmtlist );
|
|
|
|
/** Get list of encodings known to the library.
|
|
* You are responsible for freeing the allocated array.
|
|
* \param enclist return address for allocated array of encoding codes
|
|
* \return number of encodings, -1 on error
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_enc_list(int **enclist);
|
|
|
|
/** Find encoding code by name.
|
|
* \param name short or long name to find encoding code for
|
|
* \return encoding if found (enum #mpg123_enc_enum), else 0
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_enc_byname(const char *name);
|
|
|
|
/** Get name of encoding.
|
|
* \param encoding code (enum #mpg123_enc_enum)
|
|
* \return short name for valid encodings, NULL otherwise
|
|
*/
|
|
MPG123_EXPORT
|
|
const char* out123_enc_name(int encoding);
|
|
|
|
/** Get long name of encoding.
|
|
* \param encoding code (enum #mpg123_enc_enum)
|
|
* \return long name for valid encodings, NULL otherwise
|
|
*/
|
|
MPG123_EXPORT
|
|
const char* out123_enc_longname(int encoding);
|
|
|
|
/** Start playback with a certain output format
|
|
* It might be a good idea to have audio data handy to feed after this
|
|
* returns with success.
|
|
* Rationale for not taking a pointer to struct mpg123_fmt: This would
|
|
* always force you to deal with that type and needlessly enlarge the
|
|
* shortest possible program.
|
|
* \param ao handle
|
|
* \param encoding sample encoding (values matching libmpg123 API)
|
|
* \param channels number of channels (1 or 2, usually)
|
|
* \param rate sampling rate
|
|
* \return 0 on success, negative on error (bad format, usually)
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_start( out123_handle *ao
|
|
, long rate, int channels, int encoding );
|
|
|
|
/** Pause playback
|
|
* Interrupt playback, holding any data in the optional buffer.
|
|
*
|
|
* This closes the audio device if it is a live sink, ready to be re-opened
|
|
* by out123_continue() or out123_play() with the existing parameters.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_pause(out123_handle *ao);
|
|
|
|
/** Continue playback
|
|
* The counterpart to out123_pause(). Announce to the driver that playback
|
|
* shall continue.
|
|
*
|
|
* Playback might not resume immediately if the optional buffer is configured
|
|
* to wait for a minimum fill and close to being empty. You can force playback
|
|
* of the last scrap with out123_drain(), or just by feeding more data with
|
|
* out123_play(), which will trigger out123_continue() for you, too.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_continue(out123_handle *ao);
|
|
|
|
/** Stop playback.
|
|
* This waits for pending audio data to drain to the speakers.
|
|
* You might want to call out123_drop() before stopping if you want
|
|
* to end things right away.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_stop(out123_handle *ao);
|
|
|
|
/** Hand over data for playback and wait in case audio device is busy.
|
|
* This survives non-fatal signals like SIGSTOP/SIGCONT and keeps on
|
|
* playing until the buffer is done with if the flag
|
|
* OUT123_KEEP_PLAYING ist set (default). So, per default, if
|
|
* you provided a byte count divisible by the PCM frame size, it is an
|
|
* error when less bytes than given are played.
|
|
* To be sure if an error occured, check out123_errcode().
|
|
* Also note that it is no accident that the buffer parameter is not marked
|
|
* as constant. Some output drivers might need to do things like swap
|
|
* byte order. This is done in-place instead of wasting memory on yet
|
|
* another copy. Software muting also overwrites the data.
|
|
* \param ao handle
|
|
* \param buffer pointer to raw audio data to be played
|
|
* \param bytes number of bytes to read from the buffer
|
|
* \return number of bytes played (might be less than given, even zero)
|
|
*/
|
|
MPG123_EXPORT
|
|
size_t out123_play( out123_handle *ao
|
|
, void *buffer, size_t bytes );
|
|
|
|
/** Drop any buffered data, making next provided data play right away.
|
|
* This does not imply an actual pause in playback.
|
|
* You are expected to play something, unless you called out123_pause().
|
|
* Feel free to call out123_stop() afterwards instead for a quicker
|
|
* exit than the implied out123_drain().
|
|
* For live sinks, this may include dropping data from their buffers.
|
|
* For others (files), this only concerns data in the optional buffer.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_drop(out123_handle *ao);
|
|
|
|
/** Drain the output, waiting until all data went to the hardware.
|
|
* This does imply out123_continue() before and out123_pause()
|
|
* after draining.
|
|
* This might involve only the optional buffer process, or the
|
|
* buffers on the audio driver side, too.
|
|
* \param ao handle
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_drain(out123_handle *ao);
|
|
|
|
/** Drain the output, but only partially up to the given number of
|
|
* bytes. This gives you the opportunity to do something while
|
|
* the optional buffer is writing remaining data instead of having
|
|
* one atomic API call for it all.
|
|
*
|
|
* It is wholly expected that the return value of out123_buffered()
|
|
* before and after calling this has a bigger difference than the
|
|
* provided limit, as the buffer is writing all the time in the
|
|
* background.
|
|
*
|
|
* This is just a plain out123_drain() if the optional buffer is not
|
|
* in use. Also triggers out123_continue(), but only out123_pause()
|
|
* if there is no buffered data anymore.
|
|
* \param ao handle
|
|
* \param bytes limit of buffered bytes to drain
|
|
* \return number of bytes drained from buffer
|
|
*/
|
|
MPG123_EXPORT
|
|
void out123_ndrain(out123_handle *ao, size_t bytes);
|
|
|
|
/** Get an indication of how many bytes reside in the optional buffer.
|
|
* This might get extended to tell the number of bytes queued up in the
|
|
* audio backend, too.
|
|
* \param ao handle
|
|
* \return number of bytes in out123 library buffer
|
|
*/
|
|
MPG123_EXPORT
|
|
size_t out123_buffered(out123_handle *ao);
|
|
|
|
/** Extract currently used audio format from handle.
|
|
* matching mpg123_getformat().
|
|
* Given return addresses may be NULL to indicate no interest.
|
|
* \param ao handle
|
|
* \param rate address for sample rate
|
|
* \param channels address for channel count
|
|
* \param encoding address for encoding
|
|
* \param framesize size of a full PCM frame (for convenience)
|
|
* \return 0 on success, -1 on error
|
|
*/
|
|
MPG123_EXPORT
|
|
int out123_getformat( out123_handle *ao
|
|
, long *rate, int *channels, int *encoding, int *framesize );
|
|
|
|
/** @} */
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif
|
|
|