[Youtube] --live-from-start support for sequence / range download

[mxvin]

Checklist

• I'm reporting a feature request
• I've looked through the README
• I've verified that I'm running yt-dlp version 2022.04.08 (update instructions) or later (specify commit)
• I've searched the bugtracker for similar issues including closed ones. DO NOT post duplicates
• I've read the guidelines for opening an issue

Description

Hi,
I try to implement capability of youtube livestream download (--live-from-start), that we can determine from which sequence it starts downloads until live/current live, or range from sequence A to sequence B by changing some parts on extractor/youtube
In my case this is working well as expected, and super useful, and I want to know what you guys think.
Maybe if this is good enough I hope I can be push it upstream, or let this be just a feature request :)

commit: mxvin@ecf8b60

my misplace comment on this feature (maybe related to that actual issue, maybe not): #2412 (comment)

Verbose log

No response

[pukkandan]

For this to be actually useful, the option needs to be time-based, not fragment based

[ohhai]

Any method of range selection would be useful, I think.
Currently it's almost impossible to download default length of long live streams (120 hours) to cut a small portion of it.

[user334]

In my case this is working well as expected, and super useful, and I want to know what you guys think.

Hi @ohhai!
Could you please share your fork of yt-dlp with this feature enabled?
I'm downloading some streams and downloading a whole stream is just.. eh.. a pain and simply unneeded most of the times. I definitely agree with you in "any method would be useful".

[NDR0216]

commit: mxvin@ecf8b60

@user334 here is the fork

[pukkandan]

If you wish, you can make a PR for it. But I don't want a new option. Instead, this can be added to --download-sections itself. Something like --download-sections "*100f-200f" (f=fragment). Even better if you can extend this to support other fragmented downloads

[NDR0216]

@pukkandan something like --live-from-start --download-sections

[danielehrhardt]

i would do something like this:
Start from 3 hours in the past:
-start=-180