-x option fails to convert to audio file without specifying --audio-format

[JaKXz]

After reading the documentation, I assumed that I could simply pass the -x option and youtube-dl would figure out that I want the best quality and best format for the video (song) I'm downloading. However, passing the --audio-format [mp3] argument is required so that the following error does not occur:

[youtube] Post-process file videoname-<videocode>.m4a exists, skipping

What I think is happening is the -x flag is changing the video format to an audio format before finishing the download and the post-processing can take place.

[JakobOvrum]

I'm experiencing this as well. This didn't happen to me before (a year ago or so?), but I don't know exactly when the change was introduced. It may also have been caused by a change in my ffmpeg environment, I don't know.

[shreve]

I'm getting this too. It's only when I want the best quality, though, because that's the file that's already downloaded. I still encounter the error if I explicitly specify --audio-format best. I'm using the latest youtube-dl and ffmpeg available through homebrew.
I'm pretty sure it has something to do with this.
I'm not familiar with this project or python, so I'm not sure how to fix it.

[phihag]

YouTube serves m4a files with a very weird header that only some players can read. youtube-dl 2015.01.23.4 and newer will automatically correct the header of the m4a file if ffmpeg is present on the system. I am therefore closing this issue. See our FAQ if you need help updating. Thank you for the report!

[shreve]

It works! Thanks, @phihag, you're my hero!