Is there somewhere an explanation available of the various formats of youtube streams (which you get when you list them in youtube-dl)?

[Emdosis]

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[dstftw]

-F.

[Emdosis]

-F.

That's not what I meant to ask, I must have worded it wrong. I already knew about that. What I want to know is if there is way to get more clear data about those streams' metadata

[Hrxn]

It's the metadata as returned by YouTube...
Pretty self-explanatory, what else do you need to know?

[Emdosis]

I understand. Though there's still one thing I'd like to ask; why are there 2 different bitrates in the dash audio formats? It's kinda confusing.
Although it seems to me like youtube-dl just downloads the second one... I just started using youtube-dl so it all seems ambiguous to me

[Hrxn]

It depends...
YouTube has some variation, depending on the upload (for example, something old, uploaded long ago vs. something new).
Although usually bitrate alone is not the only difference..
Can you post the output of -F here?

[Emdosis]

I don't really understand why you need it, it's literally the same for all youtube videos. Here's an example I guess:
`139 m4a audio only DASH audio 50k , m4a_dash container, mp4a.40.5@ 48k (22050Hz), 1.10MiB
140 m4a audio only DASH audio 129k , m4a_dash container, mp4a.40.2@128k (44100Hz), 2.94MiB

160 mp4 256x144 DASH video 108k , mp4_dash container, avc1.4d400b, 25fps, video only
133 mp4 426x240 DASH video 242k , mp4_dash container, avc1.4d400c, 25fps, video only
134 mp4 640x360 DASH video 294k , mp4_dash container, avc1.4d401e, 25fps, video only, 6.68MiB
135 mp4 854x480 DASH video 1155k , mp4_dash container, avc1.4d4014, 25fps, video only
137 mp4 1920x1080 DASH video 2240k , mp4_dash container, avc1.640028, 25fps, video only, 39.98MiB
136 mp4 1280x720 DASH video 2310k , mp4_dash container, avc1.4d4016, 25fps, video only
17 3gp 176x144 small , mp4v.20.3, mp4a.40.2@ 24k, 1.45MiB
36 3gp 320x180 small , mp4v.20.3, mp4a.40.2, 4.93MiB
18 mp4 640x360 medium , avc1.42001E, mp4a.40.2@ 96k, 10.85MiB
43 webm 640x360 medium , vp8.0, vorbis@128k, 11.53MiB
22 mp4 1280x720 hd720 , avc1.64001F, mp4a.40.2@192k (best)`

Though usually more popular videos have opus and vorbis formats in them. Like so:

`249 webm audio only DASH audio 59k , opus @ 50k, 1.31MiB
250 webm audio only DASH audio 89k , opus @ 70k, 1.90MiB

140 m4a audio only DASH audio 128k , m4a_dash container, mp4a.40.2@128k, 3.00MiB
171 webm audio only DASH audio 128k , vorbis@128k, 2.72MiB
251 webm audio only DASH audio 170k , opus @160k, 3.66MiB
278 webm 256x144 144p 26k , webm container, vp9, 30fps, video only, 541.20KiB
242 webm 426x240 240p 29k , vp9, 30fps, video only, 610.55KiB
243 webm 640x360 360p 53k , vp9, 30fps, video only, 1.08MiB
244 webm 854x480 480p 87k , vp9, 30fps, video only, 1.63MiB
160 mp4 256x144 144p 102k , avc1.4d400c, 30fps, video only, 1.09MiB
247 webm 1280x720 720p 160k , vp9, 30fps, video only, 3.26MiB
134 mp4 640x360 360p 196k , avc1.4d401e, 30fps, video only, 1.58MiB
133 mp4 426x240 240p 234k , avc1.4d4015, 30fps, video only, 2.32MiB
135 mp4 854x480 480p 411k , avc1.4d401f, 30fps, video only, 2.82MiB
136 mp4 1280x720 720p 812k , avc1.4d401f, 30fps, video only, 4.78MiB
17 3gp 176x144 small , mp4v.20.3, mp4a.40.2@ 24k, 804.63KiB
36 3gp 320x180 small , mp4v.20.3, mp4a.40.2, 2.29MiB
18 mp4 640x360 medium , avc1.42001E, mp4a.40.2@ 96k, 4.18MiB
43 webm 640x360 medium , vp8.0, vorbis@128k, 4.59MiB
22 mp4 1280x720 hd720 , avc1.64001F, mp4a.40.2@192k (best)`

[Hrxn]

Well, your examples show that it's not literally the same for all videos..

youtube-dl by default selects as format setting bestvideo+bestaudio.

In this case here, bestaudio would be 1. format 140 and for 2. format 251..

So this should work as expected. Or did you manage to produce something different here?

Or is your question more about the general principle, i.e. YouTube offering streams in many different formats?

If yes, then that is the case for support of lots of different devices with different capabilities, when it comes to formats/containers, codecs, display size/resolution and also Internet connection bandwidth of course.,

If the connection slows down, YouTube switches to formats with lower bitrates etc.

[Emdosis]

K thanks.
(tho in the first one I'd go for 22 and extract the audio)