Man I thought I was in heaven when I accidentally stumbled upon SponsorBlock. Now you're telling me about this?! Amazing! How does the video quality fare after stripping? Is it re-encoding the video or somehow stripping it without altering the quality?
I doubt it would have to re-encode. First it would split the video into separate files which don’t include the sponsored content.
Then would use something like the ffmpeg concat demuxer which will adjust timestamps of the input streams, and then output a concatenated result stream (no reencode) (https://ffmpeg.org/ffmpeg-formats.html#concat-1). So it should probably have zero quality loss.
It re-encodes. Actually, I think it defaults to marking the sponsor bits ... somehow. Whatever it's doing wasn't enough for my player to notice.
That said, for this stuff, I've only downloaded audio, and of that mostly talking head type stuff, where I let it cut out the segments. Whatever re-encoding is done would have to be pretty bad before I'd care.
$ yt-dlp -x --sponskrub --sponskrub-cut "https://www.youtube.com/watch?v=_7vPNcnYWQ4"
[youtube] _7vPNcnYWQ4: Downloading webpage
[youtube] _7vPNcnYWQ4: Downloading android player API JSON
[info] _7vPNcnYWQ4: Downloading 1 format(s): 251
[download] Destination: Making an unpickable lock. Calling locksmiths [_7vPNcnYWQ4].webm
[download] 100% of 12.72MiB in 00:00
[ExtractAudio] Destination: Making an unpickable lock. Calling locksmiths [_7vPNcnYWQ4].opus
Deleting original file Making an unpickable lock. Calling locksmiths [_7vPNcnYWQ4].webm (pass -k to keep)
[SponSkrub] Trying to remove sponsor sections
WARNING: Cutting out sponsor segments will cause the subtitles to go out of sync.
[libopus @ 0x5462c20] No bit rate set. Defaulting to 96000 bps.
size= 3515kB time=00:04:33.53 bitrate= 105.3kbits/s speed= 26x
Without the audio only option, it's more clear it's re-encoding:
[SponSkrub] Trying to remove sponsor sections
WARNING: Cutting out sponsor segments will cause the subtitles to go out of sync.
[libopus @ 0x5575420] No bit rate set. Defaulting to 96000 bps.
frame= 51 fps=8.5 q=0.0 size= 1kB time=00:00:01.95 bitrate= 3.5kbits/s speed=0.326x
