arcodange/mediabunny
1
0
Fork 0
mirror of https://github.com/arcodange-org/mediabunny.git synced 2026-09-30 20:33:55 +02:00
Code Issues Packages Projects Releases Wiki Activity

Add new slice-based reader system, port all demuxers to new reader system, add optimized BlobSource

Browse Source
This commit is contained in:
Vanilagy
2025-08-28 17:24:31 +02:00
parent 0e6cddc941
commit 641cdd02e3
17 changed files with 2230 additions and 1772 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/adts/adts-reader.ts
+58 -69
View File
@@ -7,8 +7,9 @@
*/
import { Bitstream } from '../misc';
import { Reader } from '../reader';
import { FileSlice, readBytes } from '../reader2';
export const MIN_FRAME_HEADER_SIZE = 7;
export const MAX_FRAME_HEADER_SIZE = 9;
export type FrameHeader = {
@@ -21,76 +22,64 @@ export type FrameHeader = {
startPos: number;
};
export class AdtsReader {
pos = 0;
constructor(public reader: Reader) {}
export const readFrameHeader = (slice: FileSlice): FrameHeader | null => {
// https://wiki.multimedia.cx/index.php/ADTS (last visited: 2025/08/17)
readBytes(length: number) {
const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + length);
this.pos += length;
const startPos = slice.filePos;
return new Uint8Array(view.buffer, offset, length);
const bytes = readBytes(slice, 9); // 9 with CRC, 7 without CRC
const bitstream = new Bitstream(bytes);
const syncword = bitstream.readBits(12);
if (syncword !== 0b1111_11111111) {
return null;
}
readFrameHeader(): FrameHeader | null {
// https://wiki.multimedia.cx/index.php/ADTS (last visited: 2025/08/17)
const startPos = this.pos;
const bytes = this.readBytes(9); // 9 with CRC, 7 without CRC
const bitstream = new Bitstream(bytes);
const syncword = bitstream.readBits(12);
if (syncword !== 0b1111_11111111) {
return null;
}
bitstream.skipBits(1); // MPEG version
const layer = bitstream.readBits(2);
if (layer !== 0) {
return null;
}
const protectionAbsence = bitstream.readBits(1);
const objectType = bitstream.readBits(2) + 1;
const samplingFrequencyIndex = bitstream.readBits(4);
if (samplingFrequencyIndex === 15) {
return null;
}
bitstream.skipBits(1); // Private bit
const channelConfiguration = bitstream.readBits(3);
if (channelConfiguration === 0) {
throw new Error('ADTS frames with channel configuration 0 are not supported.');
}
bitstream.skipBits(1); // Originality
bitstream.skipBits(1); // Home
bitstream.skipBits(1); // Copyright ID bit
bitstream.skipBits(1); // Copyright ID start
const frameLength = bitstream.readBits(13);
bitstream.skipBits(11); // Buffer fullness
const numberOfAacFrames = bitstream.readBits(2) + 1;
if (numberOfAacFrames !== 1) {
throw new Error('ADTS frames with more than one AAC frame are not supported.');
}
let crcCheck: number | null = null;
if (protectionAbsence === 1) { // No CRC
this.pos -= 2;
} else { // CRC
crcCheck = bitstream.readBits(16);
}
return {
objectType,
samplingFrequencyIndex,
channelConfiguration,
frameLength,
numberOfAacFrames,
crcCheck,
startPos,
};
bitstream.skipBits(1); // MPEG version
const layer = bitstream.readBits(2);
if (layer !== 0) {
return null;
}
}
const protectionAbsence = bitstream.readBits(1);
const objectType = bitstream.readBits(2) + 1;
const samplingFrequencyIndex = bitstream.readBits(4);
if (samplingFrequencyIndex === 15) {
return null;
}
bitstream.skipBits(1); // Private bit
const channelConfiguration = bitstream.readBits(3);
if (channelConfiguration === 0) {
throw new Error('ADTS frames with channel configuration 0 are not supported.');
}
bitstream.skipBits(1); // Originality
bitstream.skipBits(1); // Home
bitstream.skipBits(1); // Copyright ID bit
bitstream.skipBits(1); // Copyright ID start
const frameLength = bitstream.readBits(13);
bitstream.skipBits(11); // Buffer fullness
const numberOfAacFrames = bitstream.readBits(2) + 1;
if (numberOfAacFrames !== 1) {
throw new Error('ADTS frames with more than one AAC frame are not supported.');
}
let crcCheck: number | null = null;
if (protectionAbsence === 1) { // No CRC
slice.filePos -= 2;
} else { // CRC
crcCheck = bitstream.readBits(16);
}
return {
objectType,
samplingFrequencyIndex,
channelConfiguration,
frameLength,
numberOfAacFrames,
crcCheck,
startPos,
};
};