diff options
| -rw-r--r-- | dxr3audiodecoder.c | 78 | ||||
| -rw-r--r-- | dxr3audiodecoder.h | 2 |
2 files changed, 74 insertions, 6 deletions
diff --git a/dxr3audiodecoder.c b/dxr3audiodecoder.c index d65689c..b909485 100644 --- a/dxr3audiodecoder.c +++ b/dxr3audiodecoder.c @@ -101,13 +101,16 @@ void cDxr3AudioDecoder::Decode(cDxr3PesFrame *frame, uint32_t pts, cDxr3SyncBuff if ((buf[2] & 0xf0) != (lastBitrate & 0xf0)) { dsyslog("[dxr3-audiodecoder] found new audio header"); + // recalculate used framesize + frameSize = calcFrameSize(buf); + dsyslog("[dxr3-audiodecoder] calculated frame size %d", frameSize); + // we need now to reinit the deocder and to store the new // part from the audio header Init(); lastBitrate = buf[2]; } } - #if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(52, 26, 0) uint8_t *ptr = const_cast<uint8_t *>(buf); @@ -115,9 +118,9 @@ void cDxr3AudioDecoder::Decode(cDxr3PesFrame *frame, uint32_t pts, cDxr3SyncBuff out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE; #if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(51, 29, 0) - len = avcodec_decode_audio(contextAudio, (short *)(&pcmbuf), &out_size, ptr, length); + len = avcodec_decode_audio(contextAudio, (short *)(&pcmbuf), &out_size, ptr, frameSize); #else - len = avcodec_decode_audio2(contextAudio, (short *)(&pcmbuf), &out_size, ptr, length); + len = avcodec_decode_audio2(contextAudio, (short *)(&pcmbuf), &out_size, ptr, frameSize); #endif if (len < 0) { @@ -139,9 +142,9 @@ void cDxr3AudioDecoder::Decode(cDxr3PesFrame *frame, uint32_t pts, cDxr3SyncBuff } #else avpkt.data = const_cast<uint8_t *>(buf); - avpkt.size = length; + avpkt.size = frameSize; - while (avpkt.size > 0) { + while (length > 0) { out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE; len = avcodec_decode_audio3(contextAudio, (short *)(&pcmbuf), &out_size, &avpkt); @@ -160,7 +163,7 @@ void cDxr3AudioDecoder::Decode(cDxr3PesFrame *frame, uint32_t pts, cDxr3SyncBuff } } - avpkt.size -= len; + length -= len; avpkt.data += len; } #endif @@ -288,6 +291,69 @@ bool cDxr3AudioDecoder::checkMpegAudioHdr(const uint8_t *head) return true; } +int cDxr3AudioDecoder::calcFrameSize(const uint8_t *header) +{ + static const int bitrates[2][3][15] = + { + { // MPEG 1 + {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,}, // Layer1 + {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,}, // Layer2 + {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,} // Layer3 + }, + { // MPEG 2, 2.5 + {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,}, // Layer1 + {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,}, // Layer2 + {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,} // Layer3 + } + }; + + static const int samplingRates[4][3] = + { + {11025, 12000, 8000, }, // MPEG 2.5 + {0, 0, 0, }, // reserved + {22050, 24000, 16000, }, // MPEG 2 + {44100, 48000, 32000 } // MPEG 1 + }; + + static const int MPEG1 = 0x3; + + // in B the version is stored + int ver = (header[1] >> 3) & 0x03; + int version = 1; // default to MPEG2 + + // determine index into arrays based on ver + if (ver == MPEG1) { + version = 0; + } + + // in C the layer version is stored + int layer = 3 - ((header[1] >> 1) & 0x03); + + // in E the bitrate index is stored + int bitrateIndex = (header[2] >> 4) & 0x0f; + + // in F the sampling rate frequency index is stored + int samplingIndex = (header[2] >> 2) & 0x03; + + // in G the padding bit is stored + int padding = (header[2] >> 1) & 0x01; + + int bitrate = bitrates[version][layer][bitrateIndex]; // kbit + bitrate *= 1000; // kbit -> bit + int samplesrate = samplingRates[ver][samplingIndex]; + + // formulars used to calculate frame size + // layer I + // FrameLengthInBytes = (12 * BitRate / SampleRate + Padding) * 4 + // layer II & III + // FrameLengthInBytes = 144 * BitRate / SampleRate + Padding + if (layer == 0) { + return (12 * bitrate / samplesrate + padding) * 4; + } else { + return 144 * bitrate / samplesrate + padding; + } +} + // Local variables: // mode: c++ // c-file-style: "stroustrup" diff --git a/dxr3audiodecoder.h b/dxr3audiodecoder.h index 48b526b..7b0262f 100644 --- a/dxr3audiodecoder.h +++ b/dxr3audiodecoder.h @@ -55,6 +55,7 @@ public: private: bool checkMpegAudioHdr(const uint8_t *head); + int calcFrameSize(const uint8_t *header); AVCodec *audio; AVCodecContext *contextAudio; @@ -63,6 +64,7 @@ private: cRingBufferFrame rbuf; cMultichannelAudio ac3dtsDecoder; + int frameSize; uint8_t lastBitrate; uint8_t pcmbuf[AVCODEC_MAX_AUDIO_FRAME_SIZE]; }; |