Convert downloaded YouTube videos (downloaded with youtube-dl) to audio-only, with no loss?

Question

If one downloads videos from YouTube using youtube-dl, they get .mp4 files which are a ISO Media, MPEG v4 system, version 2.

Can these files be converted to audio-only, ideally with no quality loss?
The goal is to save space by throwing out the unneeded visual part.

even after you convert it to mp3, I don't think the size will change see my question from yesterday http://askubuntu.com/questions/421777/is-it-possible-to-restore-the-original-quality-of-a-youtube-video-after-download — Lynob, Feb 17 '14 at 11:37
Voting to keep this open, as the answers and question here are superior, and with a slightly different focus. — belacqua, Feb 17 '14 at 23:25
Voting to close. There is already a question about How to extract audio from video files. — Lucio, Feb 18 '14 at 23:31

score 10 · Answer 1 · edited Mar 16 '18 at 07:11

10

You can convert to audio only formats using youtube-dl itself, although it still downloads the video and then converts it.

To do this, use -x or --extract-audio to the command, for example:

youtube-dl -x 'http://www.youtube.com/watch?v=0iyeUcFKRv4&feature=c4-overview&list=UU1KPy3cAAj0i0RIFC_SzjMg'

edited Mar 16 '18 at 07:11

l0b0

8,819

answered Feb 17 '14 at 07:28

jobin

27,708

"youtube-dl -f bestaudio " also works – nwgat Feb 22 '16 at 21:23

score 8 · Answer 2 · answered Feb 17 '14 at 11:25

8

You can convert existing downloaded files using ffmpeg from the command-line

ffmpeg -i "input file.mp4" -acodec copy "output file.aac"

The "acodec copy" part is the bit that doesn't change the audio stream.

answered Feb 17 '14 at 11:25

xorsyst

181
3

score 4 · Answer 3 · answered Feb 17 '14 at 07:25

enter image description here

YouTube Center is excellent user script, which works accross browsers, doesn't involve bloating your OS with ton of Youtube downloaders unless you're a strictly 320 kbps person for your audio files. Besides, you have Handbrake at your disposal which involves bit of a manual work but will do exactly what you want. :)

score 4 · Answer 4 · edited Mar 11 '17 at 19:03

A command line alternative to download and immediately convert to a desired format is to send a file downloaded with cclive to avconv with the cclive option --exec.

Examples:

Download video, then extract the audio track to keep the original encoding:
```
cclive -f best <videolink> --exec "avconv -i '%n' -acodec copy <name>.<extension>"
```
- needs <extension> to be in the same format as the source audio format (e.g. aac)
Download video, then convert audio to mp3 (or any other supported audio codec):
```
cclive -f best <videolink> --exec "avconv -i '%n' -acodec lbmp3lame -b:a 256k <name>.mp3"
```
- will download and convert to 256 kb/s mp3.
Download video, copy audio, and delete video:
```
cclive -f best <videolink> --exec "avconv -i '%n' -acodec copy <name>.aac" --exec "rm '%n'"
```
- will delete the downloaded video after audio extraction.

We are quite versatile to convert to any audio codec avconv can encode, and this will also work on download sites other than YouTube.

Note for cclive >= 0.7.12 in Ubuntu >= 13.10:
Option -f was replaced by option -s. Give option -s best for best available encoding, -s <ID> for any other encoding as can be listed with cclive -S <URL>.

score 3 · Answer 5 · edited Apr 13 '17 at 12:23

youtube-dl --help explains how:

  Post-processing Options:
    -x, --extract-audio              convert video files to audio-only
                                     files (requires ffmpeg or avconv and
                                     ffprobe or avprobe)
    --audio-format FORMAT            "best", "aac", "vorbis", "mp3", "m4a",
                                     "opus", or "wav"; best by default
    --audio-quality QUALITY          ffmpeg/avconv audio quality
                                     specification, insert a value between
                                     0 (better) and 9 (worse) for VBR or a
                                     specific bitrate like 128K (default 5)

Also look at my answer here which describes how to download just the audio instead of first downloading the video+audio and then discarding the video which is just wasteful.

Convert downloaded YouTube videos (downloaded with youtube-dl) to audio-only, with no loss?

5 Answers5

Examples: