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Code Issues Releases Wiki Activity

Add support for AAC-LC codec

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This commit is contained in:
Jeff Schiller 2022-10-30 23:47:38 -07:00
parent 73cfa291f6
commit 744162ec5b
3 changed files with 77 additions and 3 deletions
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43
codecs/codecs.js
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@ -50,6 +50,13 @@ export function getShortMIMEString(info) {
if (!info) throw `Invalid ProbeInfo`;
if (!info.streams || info.streams.length === 0) throw `No streams in ProbeInfo`;
// mp3 files are always considered audio/.
if (info.format.format_name === 'mp3') {
return 'audio/mpeg';
}
// Otherwise, any file with at least 1 video stream is considered video/.
// Otherwise, any file with at least 1 audio stream is considered audio/.
const type = info.streams.some(s => s.codec_type === 'video') ?
'video' :
info.streams.some(s => s.codec_type === 'audio') ? 'audio' : undefined;
@ -98,16 +105,30 @@ export function getShortMIMEString(info) {
export function getFullMIMEString(info) {
/** A string like 'video/mp4' */
let contentType = `${getShortMIMEString(info)}`;
// If MP3, just send back the type.
if (contentType === 'audio/mpeg') {
return contentType;
}
let codecFrags = new Set();
for (const stream of info.streams) {
if (stream.codec_type === 'audio') {
// TODO! At least mp4a!
switch (stream.codec_tag_string) {
case 'mp4a': codecFrags.add(getMP4ACodecString(stream)); break;
// TODO: vorbis.
// TODO: opus.
default:
}
}
else if (stream.codec_type === 'video') {
switch (stream.codec_tag_string) {
case 'avc1': codecFrags.add(getAVC1CodecString(stream)); break;
case 'vp09': codecFrags.add(getVP09CodecString(stream)); break;
// We don't handle these as video streams with codecs, so skip them.
case 'png':
case 'mjpeg':
continue;
default:
throw `Could not handle codec_tag_string ${stream.codec_tag_string} yet. ` +
`Please file a bug https://github.com/codedread/bitjs/issues/new`;
@ -116,7 +137,6 @@ export function getFullMIMEString(info) {
}
if (codecFrags.length === 0) return contentType;
return contentType + '; codecs="' + Array.from(codecFrags).join(',') + '"';
}
@ -215,3 +235,22 @@ function getVP09CodecString(stream) {
return frag;
}
/**
* https://developer.mozilla.org/en-US/docs/Web/Media/Formats/codecs_parameter#mp4a
* @param {ProbeStream} stream
* @returns {string}
*/
function getMP4ACodecString(stream) {
let frag = 'mp4a.40';
switch (stream.profile) {
case 'LC':
frag += '.2';
break;
// TODO: more!
default:
throw `Cannot handle AAC stream with profile ${stream.profile} yet. ` +
`Please file a bug https://github.com/codedread/bitjs/issues/new`;
}
return frag;
}