软编码Flv 到Mp4 容器外传一avcc box
avcc是坦率的枫叶/p> AVC decoder configuration record
定义
aligned(8) class AVCDecoderConfigurationRecord { unsigned int(8) configurationVersion = 1; unsigned int(8) AVCProfileIndication; unsigned int(8) profile_compatibility; unsigned int(8) AVCLevelIndication;bit(6) reserved = ‘111111’b;unsigned int(2) lengthSizeMinusOne;bit(3) reserved = ‘111’b;unsigned int(5) numOfSequenceParameterSets;for (i=0; i< numOfSequenceParameterSets; i++) { unsigned int(16) sequenceParameterSetLength ; bit(8*sequenceParameterSetLength) sequenceParameterSetNALUnit; }unsigned int(8) numOfPictureParameterSets;for (i=0; i< numOfPictureParameterSets; i++) { unsigned int(16) pictureParameterSetLength; bit(8*pictureParameterSetLength) pictureParameterSetNALUnit; }} > lengthSizeMinusOneindicates the length in bytes of the NALUnitLength field in an AVC video sample or AVC parameter set sample of the associated stream minus one. For example, a size of one byte is indicated with a value of 0. The value of this field shall be one of 0, 1, or 3 corresponding to a length encoded with 1, 2, or 4 bytes, respectively.> numOfSequenceParameterSetsindicates the number of SPSs that are used as the initial set of SPSs for decoding the AVC elementary stream.> sequenceParameterSetLength indicates the length in bytes of the SPS NAL unit as defined in ISO/IEC 14496-10.> sequenceParameterSetNALUnit contains a SPS NAL unit, as specified in ISO/IEC 14496-10. SPSs shall occur in order of ascending parameter set identifier with gaps being allowed.> numOfPictureParameterSets indicates the number of picture parameter sets (PPSs) that are used as the initial set of PPSs for decoding the AVC elementary stream.> pictureParameterSetLength indicates the length in bytes of the PPS NAL unit as defined in ISO/IEC 14496-10.> pictureParameterSetNALUnit contains a PPS NAL unit, as specified in ISO/IEC 14496-10. PPSs shall occur in order of ascending parameter set identifier with gaps being allowed.是第一个video tag的body
v= (video tag).body//略过前5个字节let offset=5;let version = v.getUint8(offset+0); // configurationVersionlet avcProfile = v.getUint8(offset+1); // avcProfileIndicationlet profileCompatibility = v.getUint8(offset+2); // profile_compatibilitylet avcLevel = v.getUint8(offset+3); // AVCLevelIndicationthis._naluLengthSize = (v.getUint8(offset+4) & 3) + 1; // lengthSizeMinusOne 上一个avc 长度let spsCount = v.getUint8(offset+5) & 31; // numOfSequenceParameterSetslet offset = offset+6;for (let i = 0; i < spsCount; i++) { let len = v.getUint16(offset, !le); // sequenceParameterSetLength offset += 2; if (len === 0) { continue; } // Notice: Nalu without startcode header (00 00 00 01) let sps = new Uint8Array(v.buffer, offset, len); offset += len; let config = SPSParser.parseSPS(sps); meta.codecWidth = config.codec_size.width; meta.codecHeight = config.codec_size.height; meta.presentWidth = config.present_size.width; meta.presentHeight = config.present_size.height; meta.profile = config.profile_string; meta.level = config.level_string; meta.bitDepth = config.bit_depth; meta.chromaFormat = config.chroma_format; meta.sarRatio = config.sar_ratio; meta.frameRate = config.frame_rate; if (config.frame_rate.fixed === false || config.frame_rate.fps_num === 0 || config.frame_rate.fps_den === 0) { meta.frameRate = this._referenceFrameRate; } let fps_den = meta.frameRate.fps_den; let fps_num = meta.frameRate.fps_num; meta.refSampleDuration = Math.floor(meta.timescale * (fps_den / fps_num)); let codecArray = sps.subarray(1, 4); let codecString = 'avc1.'; for (let j = 0; j < 3; j++) { let h = codecArray[j].toString(16); if (h.length < 2) { h = '0' + h; } codecString += h; } meta.codec = codecString; let mi = this._mediaInfo; mi.width = meta.codecWidth; mi.height = meta.codecHeight; mi.fps = meta.frameRate.fps; mi.profile = meta.profile; mi.level = meta.level; mi.chromaFormat = config.chroma_format_string; mi.sarNum = meta.sarRatio.width; mi.sarDen = meta.sarRatio.height; mi.videoCodec = codecString; if (mi.hasAudio) { if (mi.audioCodec != null) { mi.mimeType = 'video/x-flv; codecs="' + mi.videoCodec + ',' + mi.audioCodec + '"'; } } else { mi.mimeType = 'video/x-flv; codecs="' + mi.videoCodec + '"'; } if (mi.isComplete()) { this._onMediaInfo(mi); } } let ppsCount = v.getUint8(offset); // numOfPictureParameterSets if (ppsCount === 0 || ppsCount > 1) { this._onError(DemuxErrors.FORMAT_ERROR, `Flv: Invalid H264 PPS count: ${ppsCount}`); return; } offset++; for (let i = 0; i < ppsCount; i++) { let len = v.getUint16(offset, !le); // pictureParameterSetLength offset += 2; if (len === 0) { continue; } // pps is useless for extracting video information offset += len; } meta.avcc = new Uint8Array(dataSize); meta.avcc.set(new Uint8Array(arrayBuffer, dataOffset, dataSize), 0);