First ~2 seconds of audio cut off when encoding audio on Linux

[BronsonZ]

This is mostly a duplicate of #532 but thought it deserved a more thorough write up.

EDIT: A stack overflow post reporting the same behavior: https://stackoverflow.com/questions/78543368/ffmpegcore-net-cuts-off-the-fist-few-1-5-seconds-of-audio

As the title suggests, when I encode a .wav file to a .mp3 on Linux (Ubuntu 22.04 on WSL) using a pipe input with .FromPipeInput() the first couple seconds (~2) of audio is cut off in the resulting mp3. This only appears to happen on Linux, I have not encountered it when running it on Windows. The following code is afflicted, where both inputWavStream and outputMp3Stream are of type MemoryStream:

await FFMpegArguments
    .FromPipeInput(new StreamPipeSource(inputWavStream))
    .OutputToPipe(
        new StreamPipeSink(outputMp3Stream),
        options => options
            .ForceFormat("mp3")
            .WithAudioCodec(AudioCodec.LibMp3Lame)
            .WithAudioBitrate(AudioQuality.Normal))
    .ProcessAsynchronously();

If I set the input to be a file with .FromFileInput(), no audio is cut off, regardless of what the output type is. So it seems the problem is narrowed down to something to do with using input pipes on Linux.

It could be that this is a problem with ffmpeg or libmp3lame on Linux, not necessarily an issue with FFMpegCore.

Also, it's not affected by the length of the input file, a 3 second clip is cut down to 1 second, and a 60 second clip is cut down to 58 seconds.

ffmpeg versions used:

• Linux: 4.4.2-0ubuntu0.22.04.1 and 6.1
• Windows: 7.0.2-full_build-www.gyan.dev