Pipe is broken for .m4a files

[Maitrog]

Hi, everyone!

I have a code that converting audio files to mp3

public async Task<Stream> ConvertAsync(
        MemoryStream inputAudioStream,
        string extension = "webm",
        CancellationToken cancellationToken = default)
{
    var outputMp3Stream = new MemoryStream();
    var isResultSuccess = await FFMpegArguments
                    .FromPipeInput(new StreamPipeSource(inputAudioStream))
                    .OutputToPipe(new StreamPipeSink(outputMp3Stream), ConfigureMp3)
                    .ProcessAsynchronously();

    return isResultSuccess ? outputMp3Stream : null;
}


private static void ConfigureMp3(FFMpegArgumentOptions options)
{
    options
        .WithAudioCodec(AudioCodec.LibMp3Lame)
        .WithAudioBitrate(64)
        .WithAudioSamplingRate(32000)
        .WithCustomArgument("-ac 1")
        .WithCustomArgument(
            "-af afftdn=nr=12:nf=-40:tn=1," +
            "loudnorm=I=-16:TP=-1.5:LRA=11:linear=true")
        .ForceFormat("mp3");
}

When I'm trying to convert .m4a file I get an error

[mov,mp4,m4a,3gp,3g2,mj2 @ 0000025fd66a7600] stream 0, offset 0x216: partial file
[in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 0000025fd66a7340] Error during demuxing: Invalid argument
[af#0:0 @ 0000025fd66ed500] No filtered frames for output stream, trying to initialize anyway.

All output can see here: pipe output.txt

But when I'm converting .m4a file using FromFileInput() function all working good, also no errors when I'm using ffmpeg in console
FromFileInput() output: file output.txt

File with problem: link
How I can fix it?

[ghost1face]

I just encountered the same, wondering if you found anything yet @Maitrog

[Maitrog]

If I understand right how it is work, this is a combination of 2 facts
First, pipes are not seekable.
Second, the mpeg format structure. Mpeg allows not straight order of blocks, it means video/audio tracks can be placed both at the beginning and at the end. To find right track we are reading offset and tag's name coded in block's tag, then we move into the found block like in a tree. Sometimes we found wrong tags and we need to move back to a parent "node" and there we need seekable stream and there pipe breaks.

If I'm right we can't use pipes safely for any mpeg formats like .m4a, .mp4. But I think we'll mostly face with it in files from iPhones and other Apple's devices, because they love to do weird thigs