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shellffmpeggrepyoutube-dl

Learning Shell - creating a script with parameters that runs two separate cli apps

I want to learn shell script, so I'm trying to download a youtube video using youtube-dl then convert it to mp3 using ffmpeg.

I do it manually running youtube-dl http://youtube.com/watch?v=... then ffmpeg -i downloadedFile -ab 256000 -ar 44100 audioFile.mp3.

I know that I need to pass two arguments to my script, one for the video url and another for the audio file to keep things as simple as possible, but I don't know how to start. Maybe grep the video id in the url and using it to know which file to use to convert into mp3? (since youtube-dl saves the video named by it's id)

Can someone recommend me an article or documentation that can help me?

Solution

  • You can use the --output parameter of youtube-dl to have an arbitrary template. Additionally, youtube-dl can already convert to mp3! Try

    #!/bin/sh
youtube-dl -o '%(title)s.%(ext)s' -x --audio-format mp3 -- "$1"
    • -o or --output defines the output name. You can use a number of templates, including %(title)s for the title of the video, %(ext)s for the extension, and %(id)s for the video ID. You can also use static filenames such as 'audio.%(ext)s, which will result in anaudio.mp3` file.
    • -x or --extract-audio advises youtube-dl to convert the video to an audio file (and remove the video file afterwards unless you pass -k). However, in contrast to your solution, youtube-dl will not recode audio streams that are already in mp3 - even with a relatively high bitrate such as 256k, you'll lose quality when you decode mp3 and re-encode it afterwards.
    • If you want a specific bitrate, use the --audio-quality parameter, say --audio-quality 256k.
    • The --audio-format parameter advises youtube-dl to convert audio to the given format. You can use best to always get the original audio (and not lose any quality), in whatever format it is.
    • "$1" is the first parameter of your shell script. You can pass in whole URLs, video IDs, or some shortcuts (like ytsearch:python to search YouTube for "python" and pick the first video.