Videos with uncompressed PCM audio don't play sound properly

[Mike Hicks]

I am using openshot-1.1.3-karmic1 on Ubuntu 9.10, installed from PPA. I also have melt-0.4.4-2build1 installed.

I am trying to edit videos created by my Canon EOS Rebel T2i (aka 550D and Kiss X4). This camera uses a .mov file format using h.264 video with uncompressed PCM audio. When I try to play the video in OpenShot, audio is only output for a fraction of a second.

Sound works correctly when I play files using "ffplay".

Sound fails after a fraction of a second when I play files with "melt".

Here's what "ffmpeg -i" says when I point it at one of my files:

    Seems stream 0 codec frame rate differs from container frame rate: 59.94 (60000/1001) -> 29.97 (30000/1001)
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'mvi_0272.mov':
      Duration: 00:00:16.54, start: 0.000000, bitrate: 47683 kb/s
        Stream #0.0(eng): Video: h264, yuv420p, 1920x1080, 29.97 tbr, 29.97 tbn, 59.94 tbc
        Stream #0.1(eng): Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
    At least one output file must be specified

For the moment, it appears I will be able to get around this by transcoding audio in the files (from PCM to AC3) with a command similar to this:

    ffmpeg -i input.mov -vcodec copy -acodec ac3 -ab 384k output.mov

I'll try to upload an attachment, a few seconds of 640x480 video. The audio is just fan noise.

[Olivier Girard (eolinwen)]

If melt can play correctly your video and ffplay can do it simply, it is a issue with MLT and not with Openshot. After, that's very strange for the audio and also in this codec.
Have you check in the preferences if for one reason or another this codec is not present ?

[Olivier Girard (eolinwen)]

If melt can play correctly your video and ffplay can do it simply, it is a issue with MLT and not with Openshot. After, that's very strange for the audio and also in this codec.
Have you check in the preferences if for one reason or another this codec is not present.

[Olivier Girard (eolinwen)]

If melt can play correctly your video and ffplay can do it simply, it is a issue with MLT and not with Openshot. After, that's very strange for the audio and also in this codec.
Have you check in the preferences if for one reason or another this codec is not present ?

[Mike Hicks (hick0088)]

Yes, I believe this is likely a bug in MLT.

Yes, a "pcm_s16le" codec is listed under Edit -> Preferences -> AV Formats, among many other "pcm_*" codecs.

[Mike Hicks (hick0088)]

I saw that Ubuntu 10.04 is using MLT version 0.5.4, so I downloaded the Ubuntu source for that version from http://packages.ubuntu.com/source/lucid/mlt and its build dependencies and built new .deb packages. I upgraded the mlt packages on my system, and it now seems to work (though I had to uninstall Kdenlive and one or two other things to get the upgrade to happen).

MLT 0.5.4 solved my audio problem, so presumably the bug is fixed for anyone running Ubuntu 10.04.

[Andy Finch (fincha)]

Thanks for the update.

[JackD (jack-leadershipbynumbers)]

Until I go to 10.04, I'm ripping the pcm with mplayer: mplayer -vc dummy -vo null -ao pcm:file=test.wav MVI_0054.MOV