94 lines
2.8 KiB
C
94 lines
2.8 KiB
C
/*
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* ac3.c: Frontend Status Monitor plugin for the Video Disk Recorder
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*
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* See the README file for copyright information and how to reach the author.
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*
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* AC3 Audio Header: http://www.atsc.org/standards/a_52a.pdf
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*/
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#include "tools.h"
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#include "ac3.h"
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int cFemonAC3::bitrateS[32] =
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{
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32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 448, 512, 576, 640, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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int cFemonAC3::frequencieS[4] =
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{
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480, 441, 320, 0
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};
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int cFemonAC3::frameS[3][32] =
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{
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{64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 448, 512, 640, 768, 896, 1024, 1152, 1280, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{69, 87, 104, 121, 139, 174, 208, 243, 278, 348, 417, 487, 557, 696, 835, 975, 1114, 1253, 1393, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{96, 120, 144, 168, 192, 240, 288, 336, 384, 480, 576, 672, 768, 960, 1152, 1344, 1536, 1728, 1920, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
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};
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cFemonAC3::cFemonAC3(cFemonAC3If *audioHandlerP)
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: audioHandlerM(audioHandlerP)
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{
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}
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cFemonAC3::~cFemonAC3()
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{
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}
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bool cFemonAC3::processAudio(const uint8_t *bufP, int lenP)
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{
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int fscod, frmsizcod, bsmod, acmod;
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int centermixlevel = AUDIO_CENTER_MIX_LEVEL_INVALID;
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int surroundmixlevel = AUDIO_SURROUND_MIX_LEVEL_INVALID;
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int dolbysurroundmode = AUDIO_DOLBY_SURROUND_MODE_INVALID;
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cFemonBitStream bs(bufP, lenP * 8);
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if (!audioHandlerM)
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return false;
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// skip PES header
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if (!PesLongEnough(lenP))
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return false;
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bs.SkipBits(8 * PesPayloadOffset(bufP));
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// http://rmworkshop.com/dvd_info/related_info/ac3hdr.htm
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// AC3 audio detection
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if (bs.GetBits(16) != 0x0B77) // syncword
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return false;
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bs.SkipBits(16); // CRC1
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fscod = bs.GetBits(2); // sampling rate values
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frmsizcod = bs.GetBits(6); // frame size code
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bs.SkipBits(5); // bitstream id
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bsmod = bs.GetBits(3); // bitstream mode
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acmod = bs.GetBits(3); // audio coding mode
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// 3 front channels
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if ((acmod & 0x01) && (acmod != 0x01))
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centermixlevel = bs.GetBits(2);
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// if a surround channel exists
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if (acmod & 0x04)
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surroundmixlevel = bs.GetBits(2);
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// if in 2/0 mode
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if (acmod == 0x02)
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dolbysurroundmode = bs.GetBits(2);
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audioHandlerM->SetAC3Bitrate(1000 * bitrateS[frmsizcod >> 1]);
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audioHandlerM->SetAC3SamplingFrequency(100 * frequencieS[fscod]);
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audioHandlerM->SetAC3Bitstream(bsmod);
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audioHandlerM->SetAC3AudioCoding(acmod);
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audioHandlerM->SetAC3CenterMix(centermixlevel);
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audioHandlerM->SetAC3SurroundMix(surroundmixlevel);
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audioHandlerM->SetAC3DolbySurround(dolbysurroundmode);
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audioHandlerM->SetAC3LFE(bs.GetBit()); // low frequency effects on
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audioHandlerM->SetAC3Dialog(bs.GetBits(5)); // dialog normalization
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return true;
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}
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