I have installed the correct packs into Audacity to recognise MP4 files and have been using this no problem to extract audio from YouTube downloads. However, when im downloading from Vimeo and import into Audacity, no waveform shows and no playback happens, however no error message shows. This only happens when i download a file from a video that was LiveStreamed and not recorded and uploaded to vimeo, however the file types are the same (MP4) which is confusing.
Using your method above i have noticed a different in file format. Youtube Live videos which audacity handles no problem shows format:MPEG-4 whereas Vimeo is showing Format:dash… Does anybody know if this can work with Audacity?
What does VLC show for an MP4 that does work in Audacity?
There’s clearly something odd about the MP4s that don’t work - if we can figure out what that is, then we may be able to come up with a convenient workaround.
Unless it’s just cropped from the bottom of the screen, the working one doesn’t use the SBR extension.
A quick Google search suggests that FFmpeg’s support for SBR is limited (only works with some frame lengths and not others).
Were you able to extract working audio from the “bad” MP4 using VLC? If so, then that may be your best workaround.
Just for info:
At some point in the future there will be an updated FFmpeg for Audacity (I don’t know when). When that is released, it “may” fix the problem so that you won’t need to use the workaround.