Mp3 duration issues

[adrydez]

Mp3 files with variable bitrate haven't the info of "duration" in seconds

To have that information. For instance, if mp3s are constant bitrate, "CBR" is recognized and "duration" is available

MP3 with constant rate info:

format: bitrate: 192000 codecProfile: "CBR" dataformat: "MPEG" duration: 15.296 encoder: "mp3" lossless: false numberOfChannels: 2 sampleRate: 48000 tagTypes: ["ID3v2.4"] tool: "LAME 3.100U"

MP3 with variable bitrate info

firmat: bitrate: 160000 dataformat: "MPEG" encoder: "mp3" lossless: false numberOfChannels: 1 sampleRate: 48000

[Borewit]

That is not necessary true @adrydez . If the duration is available in the LAME (VBR) header, it is provided. If not, there is no way to know the duration without decoding the entire audio stream, and that is not the job of the module. It decodes metadata, and does sometimes even a bit more then that, but it's not a metadata re-constructor.

Please provide a sample of you believe the duration is available and not provided.

[adrydez]

You can find two mp3 files at this address: WeTranfer One of them is constant, the other one, variable. The content on them is the same and the files have been created with adobe audition

[Borewit]

aws_Var.mp3 has no VBR header:

if there is a VBR header, the length can be derived from that:

Try the LAME encoder and you will see that it will just work fine. This is considered the best MP3 encoder.

[Borewit]

Forget what I said before, if you enable the duration flag, it will get the duration: {duration: true} by adding up the duration of each MPEG frame:

describe('#788', () => {

  const filePath = path.join(issue_path, '#788', 'aws_Var.mp3');

  it('Duration VBR', async () => {
    const {format, common} = await mm.parseFile(filePath, {duration: true});
    assert.strictEqual(format.container, 'MPEG', 'format.container');
    assert.strictEqual(format.codec, 'MPEG 1 Layer 3', 'format.codec');
    assert.isDefined(format.duration, 'format.duration');
  });

});