`pipeline` utility does not work with all commands

[asaphaaning]

Version information

• fluent-ffmpeg version: 2.1.18
• ffmpeg version: 4.4
• OS: Linux arm64 (Manjaro)

Code to reproduce

This does NOT work

    async function* test(stream) {
        for await (const chunk of stream) {
            console.log(chunk)
            yield chunk
        }
    }

    const pt = new PassThrough()

    ffmpeg(SOURCE)
        .outputFPS(FPS)
        .size(`${WIDTH}x${HEIGHT}`)
        .videoCodec('ppm')
        .withNoAudio()
        .outputFormat('image2pipe')
        .stream(pt, { end: true })

    pipeline(
       pt,
       test,
       err => console.log(err)
    )

This DOES work

  const pt = new PassThrough()

    ffmpeg(SOURCE)
        .outputFPS(FPS)
        .size(`${WIDTH}x${HEIGHT}`)
        .videoCodec('ppm')
        .withNoAudio()
        .outputFormat('image2pipe')
        .stream(pt, { end: true })

        pt.pipe(new Transform({transform(chunk, encoding, callback) {
        console.log(chunk); callback();
        }}))

Expected results

Should remain piped to child process. Even with backpressure applied. Instead, the stream ends abruptly after a second or two.

Observed results

Does not unless the chain is constructed using pipe

pipeline does seem to work fine with PCM transcoding so I'm not sure what the problem is exactly.

Checklist

• [X] I have read the FAQ
• [X] I tried the same with command line ffmpeg and it works correctly (hint: if the problem also happens this way, this is an ffmpeg problem and you're not reporting it to the right place)
• [X] I have included full stderr/stdout output from ffmpeg