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* AAC demuxer
*/
import * as ADTS from './adts';
import { logger } from '../utils/logger';
import ID3 from '../demux/id3';
class AACDemuxer {
constructor (observer, remuxer, config) {
this.observer = observer;
this.config = config;
this.remuxer = remuxer;
}
resetInitSegment (initSegment, audioCodec, videoCodec, duration) {
this._audioTrack = { container: 'audio/adts', type: 'audio', id: 0, sequenceNumber: 0, isAAC: true, samples: [], len: 0, manifestCodec: audioCodec, duration: duration, inputTimeScale: 90000 };
}
resetTimeStamp () {
}
static probe (data) {
if (!data)
return false;
// Check for the ADTS sync word
// Look for ADTS header | 1111 1111 | 1111 X00X | where X can be either 0 or 1
// Layer bits (position 14 and 15) in header should be always 0 for ADTS
// More info https://wiki.multimedia.cx/index.php?title=ADTS
const id3Data = ID3.getID3Data(data, 0) || [];
let offset = id3Data.length;
for (let length = data.length; offset < length; offset++) {
if (ADTS.probe(data, offset)) {
logger.log('ADTS sync word found !');
return true;
}
}
return false;
}
// feed incoming data to the front of the parsing pipeline
append (data, timeOffset, contiguous, accurateTimeOffset) {
let track = this._audioTrack;
let id3Data = ID3.getID3Data(data, 0) || [];
let timestamp = ID3.getTimeStamp(id3Data);
let pts = timestamp ? 90 * timestamp : timeOffset * 90000;
let frameIndex = 0;
let stamp = pts;
let length = data.length;
let offset = id3Data.length;
let id3Samples = [{ pts: stamp, dts: stamp, data: id3Data }];
while (offset < length - 1) {
if (ADTS.isHeader(data, offset) && (offset + 5) < length) {
ADTS.initTrackConfig(track, this.observer, data, offset, track.manifestCodec);
let frame = ADTS.appendFrame(track, data, offset, pts, frameIndex);
if (frame) {
offset += frame.length;
stamp = frame.sample.pts;
frameIndex++;
} else {
logger.log('Unable to parse AAC frame');
break;
}
} else if (ID3.isHeader(data, offset)) {
id3Data = ID3.getID3Data(data, offset);
id3Samples.push({ pts: stamp, dts: stamp, data: id3Data });
offset += id3Data.length;
} else {
// nothing found, keep looking
offset++;
}
}
this.remuxer.remux(track,
{ samples: [] },
{ samples: id3Samples, inputTimeScale: 90000 },
{ samples: [] },
timeOffset,
contiguous,
accurateTimeOffset);
}
destroy () {
}
}
export default AACDemuxer;
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