No video stream detected in VideoSource

[sofian]

I got this weird bug today. When trying to play a video file with VideoSource I get a "no video stream" warning from Drone and nothing plays.

The error seems to be coming from the fact that _formatContext->nb_streams = 0 in Gear_VideoSource.cpp (see below). What is weird is that the av_dump_format call at line 125 outputs finely:

opening movie : /home/tats/Documents/workspace/drone-0.3/GOPR1063-h264.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/tats/Documents/workspace/drone-0.3/GOPR1063-h264.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isomavc1
    creation_time   : 2012-12-04 06:01:59
    encoder         : HandBrake 0.9.8 2012071800
  Duration: 00:00:18.81, start: 0.000000, bitrate: 1508 kb/s
    Stream #0.0(und): Video: h264 (Constrained Baseline), yuv420p, 720x400 [PAR 80:81 DAR 16:9], 1122 kb/s, 29,86 fps, 29,97 tbr, 90k tbn, 180k tbc
    Metadata:
      creation_time   : 2012-12-04 06:01:59
    Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 160 kb/s
    Metadata:
      creation_time   : 2012-12-04 06:01:59
    Stream #0.2(eng): Audio: ac3, 48000 Hz, stereo, s16, 224 kb/s
    Metadata:
      creation_time   : 2012-12-04 06:01:59

Also weird is that it was working before with the exact same code! I tried to rerun the same example using the first version I was able to compile a few weeks back and it worked fine.

I tried the following withough success:

• compiling in release mode (didn't work, actually, it made Drone crash)
• re-running the whole recompilation/reinstallation of x264/libvpx/ffmpeg as described in the install section of the wiki
• compiling different branches and tags
• running valgrind (didn't show anything special)

Here's the relevant lines (125-139) in Gear_VideoSource.cpp:

  av_dump_format(_formatContext, 0, filename.c_str(), 0);

  _videoStreamIndex=-1;
  for (int i=0; i<_formatContext->nb_streams; i++)
    if (_formatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
    {
      _videoStreamIndex=i;
      break;
    }

  if (_videoStreamIndex<0)
  {
    std::cout << "no video stream!" << std::endl;
    return false;
  }

[sofian]

I tried to run a simple example from an ffmpeg tutorial (see tutorial01.c). It has more or less the same code and it runs perfectly. I am starting to believe in more of a memory management error (especially since the "release" version seems to crash). It would help if someone else could reproduce the error under Linux.

[sofian]

This is so weird: now I'm trying to run my old exec of drone (which was working about an hour ago and which I made a backup of) and it doesn't work anymore (same problem).

[jukea]

hey,could it have to do with the fact that we're using ffmpeg 0.8 instead
of 0.7 (which was the version at the time ?)

On Thu, Dec 27, 2012 at 7:31 PM, sofian [email protected] wrote:

This is so weird: now I'm trying to run my old exec of drone (which was
working about an hour ago and which I made a backup of) and it doesn't work
anymore (same problem).

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/6#issuecomment-11722298.

julien keable, ingénieur projets web | espresso communication & design
| 514.286.9696

[sofian]

Sorry, I understand this was confusing: when I talk about "my old exec of drone" I talk about the version I compiled a few weeks ago (see tag 2012-12-14--tats-linux-drone-revival). Anyway, it doesn't work anymore.

I tried again by including in the gears folder only StringSource, VideoSource and VideoOutput to reduce the chances of error due to mem allocation but I still got the same problem.

It might be because of conflicting versions of ffmpeg or related libraries. I noticed that a week ago apt-get update updated some av* libs, might be related to that. I still don't understand why the ffmpeg tutorial example works and not VideoSource, but it might be because they are not referring to the same library versions: the main difference between both is that the drone gear is compiled into a shared library whereas the tutorial example is compiled into an exec file: maybe the shared library and the static one for some av lib differ.