da1973bcd9
Bundle libOpenMPT as a dynamic framework, which should be safe once again, now that there is only one version to bundle. Also, now it is using the versions of libvorbisfile and libmpg123 that are bundled with the player, instead of compiling minimp3 and stbvorbis. Signed-off-by: Christopher Snowhill <kode54@gmail.com>
113 lines
3.3 KiB
C++
113 lines
3.3 KiB
C++
/*
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* MPEGFrame.cpp
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* -------------
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* Purpose: Basic MPEG frame parsing functionality
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* Notes : (currently none)
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* Authors: OpenMPT Devs
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* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
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*/
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#include "stdafx.h"
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#include "MPEGFrame.h"
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#include "../common/FileReader.h"
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OPENMPT_NAMESPACE_BEGIN
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// Samples per frame - for each MPEG version and all three layers
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static constexpr uint16 samplesPerFrame[2][3] =
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{
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{ 384, 1152, 1152 }, // MPEG 1
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{ 384, 1152, 576 } // MPEG 2 / 2.5
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};
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// Bit rates for each MPEG version and all three layers
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static constexpr uint16 bitRates[2][3][15] =
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{
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// MPEG 1
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{
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{ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 }, // Layer 1
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384 }, // Layer 2
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{ 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 } // Layer 3
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},
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// MPEG 2 / 2.5
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{
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 }, // Layer 1
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 }, // Layer 2
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 } // Layer 3
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}
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};
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// Sampling rates for each MPEG version and all three layers
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static constexpr uint16 samplingRates[4][3] =
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{
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{ 11025, 12000, 8000 }, // MPEG 2.5
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{ 0, 0, 0 }, // Invalid
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{ 22050, 24000, 16000 }, // MPEG 2
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{ 44100, 48000, 32000 } // MPEG 1
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};
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// Samples per Frame / 8
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static constexpr uint8 mpegCoefficients[2][3] =
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{
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{ 12, 144, 144 }, // MPEG 1
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{ 12, 144, 72 } // MPEG 2 / 2.5
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};
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// Side info size = Offset in frame where Xing/Info magic starts
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static constexpr uint8 sideInfoSize[2][2] =
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{
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{ 17, 32 }, // MPEG 1
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{ 9, 17 } // MPEG 2 / 2.5
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};
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bool MPEGFrame::IsMPEGHeader(const uint8 (&header)[3])
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{
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return header[0] == 0xFF && (header[1] & 0xE0) == 0xE0 // Sync
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&& (header[1] & 0x18) != 0x08 // Invalid MPEG version
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&& (header[1] & 0x06) != 0x00 // Invalid MPEG layer
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&& (header[2] & 0x0C) != 0x0C // Invalid frequency
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&& (header[2] & 0xF0) != 0xF0; // Invalid bitrate
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}
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MPEGFrame::MPEGFrame(FileReader &file)
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: frameSize(0)
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, numSamples(0)
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, isValid(false)
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, isLAME(false)
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{
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uint8 header[4];
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file.ReadArray(header);
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if(!IsMPEGHeader(reinterpret_cast<const uint8(&)[3]>(header)))
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return;
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uint8 version = (header[1] & 0x18) >> 3;
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uint8 mpeg1 = (version == 3) ? 0 : 1;
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uint8 layer = 3 - ((header[1] & 0x06) >> 1);
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uint8 bitRate = (header[2] & 0xF0) >> 4;
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uint8 sampleRate = (header[2] & 0x0C) >> 2;
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uint8 padding = (header[2] & 0x02) >> 1;
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bool stereo = ((header[3] & 0xC0) >> 6) != 3;
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isValid = true;
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frameSize = (((mpegCoefficients[mpeg1][layer] * (bitRates[mpeg1][layer][bitRate] * 1000) / samplingRates[version][sampleRate]) + padding)) * (layer == 0 ? 4 : 1);
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numSamples = samplesPerFrame[mpeg1][layer];
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if(stereo) numSamples *= 2u;
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uint32 lameOffset = sideInfoSize[mpeg1][stereo ? 1 : 0];
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if(frameSize < lameOffset + 8)
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return;
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uint8 frame[36];
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file.ReadStructPartial(frame, lameOffset + 4);
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// Don't check first two bytes, might be CRC
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for(uint32 i = 2; i < lameOffset; i++)
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{
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if(frame[i] != 0)
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return;
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}
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// This is all we really need to know for our purposes in the MO3 decoder.
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isLAME = !memcmp(frame + lameOffset, "Info", 4) || !memcmp(frame + lameOffset, "Xing", 4);
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}
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OPENMPT_NAMESPACE_END
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