Cannot read property 'on' of undefined in "ffmpegProc.stdout.on"

[Buzut]

Hi!

I often end up with this error while trying to encode audio files:

 /home/encoder/node_modules/fluent-ffmpeg/lib/processor.js:493
            ffmpegProc.stdout.on('data', function (data) {
                             ^

TypeError: Cannot read property 'on' of undefined
    at processCB (/home/encoder/node_modules/fluent-ffmpeg/lib/processor.js:493:30)
    at /home/encoder/node_modules/fluent-ffmpeg/lib/processor.js:203:7
    at FfmpegCommand.proto._getFfmpegPath (/home/encoder/node_modules/fluent-ffmpeg/lib/capabilities.js:90:14)
    at FfmpegCommand.proto._spawnFfmpeg (/home/encoder/node_modules/fluent-ffmpeg/lib/processor.js:116:10)
    at /home/encoder/node_modules/fluent-ffmpeg/lib/processor.js:429:12
    at /home/encoder/node_modules/fluent-ffmpeg/node_modules/async/lib/async.js:52:16
    at Immediate._onImmediate (/home/encoder/node_modules/fluent-ffmpeg/node_modules/async/lib/async.js:1206:34)
    at processImmediate [as _immediateCallback] (timers.js:383:17)

As it might help, it's for mp3 encoding. Here's the code:

function encodeAudio(mediaToEncodePath, mediaEncodedPath) {
    var ffmpegCmd = ffmpeg(mediaToEncodePath);
    var ffmpegOpts = ['-ac 2', '-map 0:a', '-map_metadata -1', '-threads 0'];

    ffmpegCmd
    .audioCodec('libmp3lame')
    .audioQuality(1)
    .outputOptions(ffmpegOpts)
    .on('error', function(err) {
        console.error('FFMPEG audio error ' + err.message);
    })
    .on('end', function() {
        […]
    })
    .save(mediaEncodedPath);
}

I don't know if it can have an incidence, but it might be relevent to point out that this function is often called several times in parallel.

[njoyard]

This is really weird, I'll try to investigate a bit. Can you tell me your nodejs version, and whether the paths you use are actual physical paths ?

[Buzut]

I'm sorry I took so long to answer. I was investigating on my side too. It finally appears that I was launching too many instances of the function in parallel and ended reaching my system stack size limit! Thus, ending with undefined variables and errors.