If you’re just copying from an existing audio / video file, however, it makes no mention at all of the concern.

ffmpeg itself says that’s not a valid audio codec for the MP4 container, iff you explicitly tell it to use that as the codec. In Lightroom the video doesn’t even play correctly, because of Lightroom’s stupid habit of re-encoding the video & audio into internal caches – apparently their video decoder is somehow thrown off by the audio channel issues, too.Īfter much trial and error and many dead-ends (thank you completely bogus & wrong Stack Overflow threads… sigh) I eventually realised that the problem is apparently simply that Lightroom, VLC, etc get offended when you include pcm_s16le audio in an MP4. However, in VLC, or Lightroom, the audio is completely corrupt – just incoherent noise. The resulting trimmed MP4s play just fine in Quicktime, the Finder – anywhere that uses Apple’s decoding libraries (though I didn’t test iOS). I was originally doing something like: ffmpeg -ss 00:07 -t 00:03 -i 'IMG_0164.MP4' -async 1 -c copy 'IMG_0164_TRIMMED.MP4' Keeping the whole 30 seconds is not just unnecessary and makes viewing the videos much more tedious, but wasteful of storage space as the encoding quality from the trail camera is very inefficient (file sizes are many times larger than they should be for the quality – clearly the H.264 encoder used in the trail camera is very cheap and very bad at its job). I’ve been using ffmpeg to trim clips from a trail camera, as most of the time there’s only a few seconds of anything interesting in frame out of the 30+ seconds of video it records each time, but I don’t want to re-encode them and lose video quality as a result (or balloon file sizes tremendously with a lossless video coding).

Ffmpeg copy video and audio