[youtube] wrong best

[lilydjwg]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.06.16.1
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

>>> youtube-dl -v -F 'https://www.youtube.com/watch?v=iygjJ8M7jnM'
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '-F', 'https://www.youtube.com/watch?v=iygjJ8M7jnM']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 3.8.3 (CPython) - Linux-5.4.42-1-lily-x86_64-with-glibc2.2.5
[debug] exe versions: ffmpeg 4.2.3, ffprobe 4.2.3, rtmpdump 2.4
[debug] Proxy map: {}
[youtube] iygjJ8M7jnM: Downloading webpage
[info] Available formats for iygjJ8M7jnM:
format code  extension  resolution note
249          webm       audio only tiny   57k , opus @ 50k (48000Hz), 2.09MiB
250          webm       audio only tiny   74k , opus @ 70k (48000Hz), 2.84MiB
140          m4a        audio only tiny  146k , m4a_dash container, mp4a.40.2@128k (44100Hz), 5.24MiB
251          webm       audio only tiny  148k , opus @160k (48000Hz), 5.69MiB
160          mp4        256x144    144p  105k , avc1.4d400c, 30fps, video only, 1.45MiB
278          webm       256x144    144p  105k , webm container, vp9, 30fps, video only, 2.07MiB
242          webm       426x240    240p  240k , vp9, 30fps, video only, 3.27MiB
133          mp4        426x240    240p  251k , avc1.4d4015, 30fps, video only, 2.28MiB
243          webm       640x360    360p  424k , vp9, 30fps, video only, 5.43MiB
134          mp4        640x360    360p  486k , avc1.4d401e, 30fps, video only, 3.90MiB
135          mp4        854x480    480p  695k , avc1.4d401f, 30fps, video only, 5.69MiB
244          webm       854x480    480p  765k , vp9, 30fps, video only, 9.19MiB
136          mp4        1280x720   720p 1263k , avc1.4d401f, 30fps, video only, 9.47MiB
247          webm       1280x720   720p 1488k , vp9, 30fps, video only, 16.01MiB
248          webm       1920x1080  1080p 2654k , vp9, 30fps, video only, 31.31MiB
137          mp4        1920x1080  1080p 4254k , avc1.640028, 30fps, video only, 28.06MiB
22           mp4        1280x720   720p  362k , avc1.64001F, 30fps, mp4a.40.2@192k (44100Hz)
18           mp4        640x360    360p  373k , avc1.42001E, 30fps, mp4a.40.2@ 96k (44100Hz), 15.11MiB (best)

Description

I've noticed that youtube-dl chooses wrong formats as best recently for YouTube, e.g. in the above log 360p video is marked as best but it should be a 1080p. (Other times it chooses a 720p.)

[lilydjwg]

Excuse me, duplicate of which?

[lilydjwg]

Did you mean #4659? That one is five years old, and I notice this behavior only recently. youtube-dl happily downloaded better seperate video+audio files rathan than combined one before. Was that considered a bug and recently got fixed?

Edit: I noticed that I was using best[...]+bestaudio which may not be a valid format specifier so the behaviour has changed. I adjust my parameters so I get what I want. But still 360p is not the best audible video in the list, there is a 720p just above it.

[lilydjwg]

After digging into the source code (instead of reading previous issues or developer response), I finally see that this is a duplicate of #14143, i.e. youtube-dl chooses higher bitrates even when the codecs differ, so older codecs win over newer, more efficient ones.