From ac6e6569f08911df9d5c96285cf15325cbbf0340 Mon Sep 17 00:00:00 2001 From: Gloria Wang Date: Wed, 9 Dec 2009 15:46:19 -0800 Subject: Add support for XING header --- media/libstagefright/MP3Extractor.cpp | 193 ++++++++++++++++++++++++++++++++-- 1 file changed, 182 insertions(+), 11 deletions(-) (limited to 'media/libstagefright/MP3Extractor.cpp') diff --git a/media/libstagefright/MP3Extractor.cpp b/media/libstagefright/MP3Extractor.cpp index 39d4c0b..14e6177 100644 --- a/media/libstagefright/MP3Extractor.cpp +++ b/media/libstagefright/MP3Extractor.cpp @@ -173,6 +173,133 @@ static bool get_mp3_frame_size( return true; } +static bool parse_xing_header( + const sp &source, off_t first_frame_pos, + int32_t *frame_number = NULL, int32_t *byte_number = NULL, + char *table_of_contents = NULL, int32_t *quality_indicator = NULL, + int64_t *duration = NULL) { + + if (frame_number) { + *frame_number = 0; + } + if (byte_number) { + *byte_number = 0; + } + if (table_of_contents) { + table_of_contents[0] = 0; + } + if (quality_indicator) { + *quality_indicator = 0; + } + if (duration) { + *duration = 0; + } + + uint8_t buffer[4]; + int offset = first_frame_pos; + if (source->readAt(offset, &buffer, 4) < 4) { // get header + return false; + } + offset += 4; + + uint8_t id, layer, sr_index, mode; + layer = (buffer[1] >> 1) & 3; + id = (buffer[1] >> 3) & 3; + sr_index = (buffer[2] >> 2) & 3; + mode = (buffer[3] >> 6) & 3; + if (layer == 0) { + return false; + } + if (id == 1) { + return false; + } + if (sr_index == 3) { + return false; + } + // determine offset of XING header + if(id&1) { // mpeg1 + if (mode != 3) offset += 32; + else offset += 17; + } else { // mpeg2 + if (mode != 3) offset += 17; + else offset += 9; + } + + if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID + return false; + } + offset += 4; + // Check XING ID + if ((buffer[0] != 'X') || (buffer[1] != 'i') + || (buffer[2] != 'n') || (buffer[3] != 'g')) { + if ((buffer[0] != 'I') || (buffer[1] != 'n') + || (buffer[2] != 'f') || (buffer[3] != 'o')) { + return false; + } + } + + if (source->readAt(offset, &buffer, 4) < 4) { // flags + return false; + } + offset += 4; + uint32_t flags = U32_AT(buffer); + + if (flags & 0x0001) { // Frames field is present + if (source->readAt(offset, buffer, 4) < 4) { + return false; + } + if (frame_number) { + *frame_number = U32_AT(buffer); + } + int32_t frame = U32_AT(buffer); + // Samples per Frame: 1. index = MPEG Version ID, 2. index = Layer + const int samplesPerFrames[2][3] = + { + { 384, 1152, 576 }, // MPEG 2, 2.5: layer1, layer2, layer3 + { 384, 1152, 1152 }, // MPEG 1: layer1, layer2, layer3 + }; + // sampling rates in hertz: 1. index = MPEG Version ID, 2. index = sampling rate index + 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 + }; + if (duration) { + *duration = (int64_t)frame * samplesPerFrames[id&1][3-layer] * 1000000LL + / samplingRates[id][sr_index]; + } + offset += 4; + } + if (flags & 0x0002) { // Bytes field is present + if (byte_number) { + if (source->readAt(offset, buffer, 4) < 4) { + return false; + } + *byte_number = U32_AT(buffer); + } + offset += 4; + } + if (flags & 0x0004) { // TOC field is present + if (table_of_contents) { + if (source->readAt(offset + 1, table_of_contents, 99) < 99) { + return false; + } + } + offset += 100; + } + if (flags & 0x0008) { // Quality indicator field is present + if (quality_indicator) { + if (source->readAt(offset, buffer, 4) < 4) { + return false; + } + *quality_indicator = U32_AT(buffer); + } + } + return true; +} + static bool Resync( const sp &source, uint32_t match_header, off_t *inout_pos, uint32_t *out_header) { @@ -314,7 +441,8 @@ class MP3Source : public MediaSource { public: MP3Source( const sp &meta, const sp &source, - off_t first_frame_pos, uint32_t fixed_header); + off_t first_frame_pos, uint32_t fixed_header, + int32_t byte_number, const char *table_of_contents); virtual status_t start(MetaData *params = NULL); virtual status_t stop(); @@ -335,7 +463,9 @@ private: off_t mCurrentPos; int64_t mCurrentTimeUs; bool mStarted; - + int32_t mByteNumber; // total number of bytes in this MP3 + // TOC entries in XING header. Skip the first one since it's always 0. + char mTableOfContents[99]; MediaBufferGroup *mGroup; MP3Source(const MP3Source &); @@ -345,7 +475,8 @@ private: MP3Extractor::MP3Extractor(const sp &source) : mDataSource(source), mFirstFramePos(-1), - mFixedHeader(0) { + mFixedHeader(0), + mByteNumber(0) { off_t pos = 0; uint32_t header; bool success = Resync(mDataSource, 0, &pos, &header); @@ -369,11 +500,19 @@ MP3Extractor::MP3Extractor(const sp &source) mMeta->setInt32(kKeyBitRate, bitrate * 1000); mMeta->setInt32(kKeyChannelCount, num_channels); - off_t fileSize; - if (mDataSource->getSize(&fileSize) == OK) { - mMeta->setInt64( - kKeyDuration, - 8000LL * (fileSize - mFirstFramePos) / bitrate); + int64_t duration; + parse_xing_header( + mDataSource, mFirstFramePos, NULL, &mByteNumber, + mTableOfContents, NULL, &duration); + if (duration > 0) { + mMeta->setInt64(kKeyDuration, duration); + } else { + off_t fileSize; + if (mDataSource->getSize(&fileSize) == OK) { + mMeta->setInt64( + kKeyDuration, + 8000LL * (fileSize - mFirstFramePos) / bitrate); + } } } } @@ -391,7 +530,8 @@ sp MP3Extractor::getTrack(size_t index) { } return new MP3Source( - mMeta, mDataSource, mFirstFramePos, mFixedHeader); + mMeta, mDataSource, mFirstFramePos, mFixedHeader, + mByteNumber, mTableOfContents); } sp MP3Extractor::getTrackMetaData(size_t index, uint32_t flags) { @@ -406,7 +546,8 @@ sp MP3Extractor::getTrackMetaData(size_t index, uint32_t flags) { MP3Source::MP3Source( const sp &meta, const sp &source, - off_t first_frame_pos, uint32_t fixed_header) + off_t first_frame_pos, uint32_t fixed_header, + int32_t byte_number, const char *table_of_contents) : mMeta(meta), mDataSource(source), mFirstFramePos(first_frame_pos), @@ -414,7 +555,9 @@ MP3Source::MP3Source( mCurrentPos(0), mCurrentTimeUs(0), mStarted(false), + mByteNumber(byte_number), mGroup(NULL) { + memcpy (mTableOfContents, table_of_contents, strlen(table_of_contents)); } MP3Source::~MP3Source() { @@ -469,7 +612,35 @@ status_t MP3Source::read( } mCurrentTimeUs = seekTimeUs; - mCurrentPos = mFirstFramePos + seekTimeUs * bitrate / 8000000; + // interpolate in TOC to get file seek point in bytes + int64_t duration; + if ((mByteNumber > 0) && (mTableOfContents[0] > 0) + && mMeta->findInt64(kKeyDuration, &duration)) { + float percent = (float)seekTimeUs * 100 / duration; + float fx; + if( percent <= 0.0f ) { + fx = 0.0f; + } else if( percent >= 100.0f ) { + fx = 256.0f; + } else { + int a = (int)percent; + float fa, fb; + if ( a == 0 ) { + fa = 0.0f; + } else { + fa = (float)mTableOfContents[a-1]; + } + if ( a < 99 ) { + fb = (float)mTableOfContents[a]; + } else { + fb = 256.0f; + } + fx = fa + (fb-fa)*(percent-a); + } + mCurrentPos = mFirstFramePos + (int)((1.0f/256.0f)*fx*mByteNumber); + } else { + mCurrentPos = mFirstFramePos + seekTimeUs * bitrate / 8000000; + } } MediaBuffer *buffer; -- cgit v1.1