Youtube playlist backup and formats

[Azenet]

I use youtube-dl to backup a youtube playlist every day, but I'm running into an issue: very often I will get mp4 and mkv files of the same video in my folder. Both the files have video and audio. Is there a way I can avoid this happening ? I am running 2015.11.18, and the command line I am using is youtube-dl -i playlistUrl.

[jaimeMF]

So, what format you want?
If you only want mp4 files you can use -f bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best

[phihag]

You can also use --download-archive.

[Azenet]

Thanks for your answers, I am going to use --download-archive archive -f best --merge-output-format mkv, as I'd rather have mkv files, which seems to work for now. My actual issue was that youtube-dl would save sometimes in mp4 and sometimes in mkv, but --download-archive prevents that.

[dstftw]

--download-archive does not prevent that. What does prevent it is --merge-output-format mkv, i.e. always muxing bestvideo+bestaudio into mkv.

[Azenet]

@dstftw I meant downloading videos only once whatever the resulting format.