Download video and audio from YouTube in a single step without muxing them together

[fturco]

I currently download videos from YouTube with two steps: video stream first and then audio stream. I'd like instead to download video and audio streams from YouTube with a single invocation of the youtube-dl command, so the webpage needs to be fetched just one time. I also prefer not to mux streams them together with ffmpeg/avconv because I experienced synchronization issues in the past. Keeping them separate is fine for me because I use mplayer's -audiofile option, even if it's a little bit inconvenient. What I have in mind is something like this (for a 1080p Dash video and 128k Dash audio):

youtube-dl -f 137 -f 140 <youtube-url>

Instead of:

youtube-dl -f 137 <youtube-url>
youtube-dl -f 140 <youtube-url>

In the former example youtube-dl just ignores the first instance of the -f option and it only downloads the audio stream.

[phihag]

As is the convention for many shell programs, the latest option (-f) overwrites all before (this is useful because it allows you to easily overwrite default settings coming from a configuration file, an alias, or a programmatic invocation.

SInce youtube-dl 2014.09.18 (type youtube-dl -U to update), you can also download multiple formats, use a comma, as in youtube-dl -f 137/bestvideo,140/bestaudio. You don't need the /bestvideo part if you want youtube-dl to fail if that specific format is not available.

[fturco]

Excellent. I will try the last youtube-dl version after my next system update cycle.