Using youtube-dl: Does adaptive bitrate (ABR) affect image quality?

Question

I'm using youtube-dl and ffmpeg to get videos/frames of videos from the web. I was told that youtube (and others) use adaptive bitrate streaming, so depending on the network conditions of the user the bitrate should drop/rise, then even though resolution stays the same, image quality should change.

That got me wondering if youtube-dl has some mechanism for downloading videos with the same (presumably best) bitrate.

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So my questions are:

1) When downloading videos through youtube-dl, because of ABR, the quality of the downloaded video depends on network conditions?

2) The following shell script will get a frame of a video at 1:30, will the image quality of this frame be affected by ABR?

MP4URL=`youtube-dl -g MYVIDEOLINK`
ffmpeg -ss 1:30 -i $MP4URL -frames:v 1 myframe.png

3) If one of the previous questions is true: Is there a way to ensure a network independent quality? How?

Answer 1

Adaptive streaming is accomplished by switching between pre-encoded streams of different bitrates and/or resolutions. But the bitrate within any given pre-encoded stream does not vary too much.

YT-DL, with your command, will select the 'best' video stream, usually the one with the highest bitrate and resolution, and return its URL. This URL is a direct resource address, and there will be no switching when downloading it, even if your network gets congested.