getMediaInformation blocks forever parsing MPEG-TS streams

[leetreveil]

mobile-ffmpeg calls ffmpeg to parse out media information:

https://github.com/tanersener/mobile-ffmpeg/blob/master/ios/src/MobileFFmpeg.m#L180

This call will block forever if the stream source is live video i.e. MPEG-TS.

Instead, we should consider using ffprobe which does not block parsing live streams and should simplify the media information parsing code significantly due to the machine readable output of ffprobe:

https://ffmpeg.org/ffprobe.html#Description

[tanersener]

You may be right about this. I haven't tested getMediaInformation with live streams before. I'll make some tests soon and post an update about it.

[leetreveil]

As a short term fix we could consider removing the outfile options from the end of the args to prevent ffmpeg from blocking:

ffmpeg -i http://some_mpeg_ts_stream -hide_banner -v info -f null -

vs

ffmpeg -i http://some_mpeg_ts_stream -hide_banner

The latter complains about a missing output file and returns 1 but does not block:

Input #0, mpegts, from 'http://some_mpeg_ts_stream':
  Duration: N/A, start: 13912.704000, bitrate: N/A
  Program 1 
    Metadata:
      service_name    : Service01
      service_provider: FFmpeg
    Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x101](eng): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 185 kb/s
    Stream #0:2[0x102](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
At least one output file must be specified

That's quite hacky though as it could cause issues with return code error handling.

[tanersener]

Unfortunately implementing ffprobe effects ffmpeg and too much effort is needed to split their contexts. So ffprobe is not an option for now.

I applied your suggestions on the development branch. Outfile options are removed in getMediaInformation. As you've pointed out method call won't be blocked for live streams.

This change will be included in the next minor release.

[leetreveil]

Awesome! Thanks so much :)

[tanersener]

Awesome! Thanks so much :)

You are the one who have identified the issue and posted the fix. So I should be thanking to you 👍