It's just a wrapper for YT-DLP

I am fairly sure that if this uses yt-dlp with the default options it will grab whatever is the highest available resolution video (and most modern codec) and merge it with the highest quality available audio track.

same as just "yt-dlp https://url-of-video" from a CLI

Looks like the "best" quality setting is hardcoded currently:

https://github.com/Owez/yark/blob/676074ee3d9e379d15e52ffe2e...

It would be nice to expose this setting via config file and/or the cli.

Working on some of the groundwork of it now in https://github.com/Owez/yark/pull/57. Higher quality might be a bigger issue to tackle because of dependence on ffmpeg but it'll be done in v1.3, slated for release in about a months time.

I'm going to cap videos to 1080p by default and have a config setting to customize this.

I would actually like the opposite: cap the resolution. I don't really need 4k videos.

Frankly I'd be ecstatic if I could limit it to 30fps versions as well. Aside from the occasional speedrun I have zero desire to increase the file size by 40 percent for nothing.

What if the highest available resolution does not have an audio stream?

Normally in modern adaptive streaming, every video variant is muxed into a separate stream without audio, and different audio variants are muxed into their own individual streams.

wow, I wonder if that's why it always feels so frequent an experience of mine where the audio and video feel subtly out of sync with one another. It's very minute but detectable. Feels like that experience has increased in the last 6 months or so.

YouTube has been that way (separate streams) for a long time, definitely not anything new in the last 6 months. And they reassemble to be indistinguishable from the original combined stream, so that's not going to be the cause.

There are plenty of causes of delayed audio, however. Bluetooth is a big one, if your device and software aren't properly compensating for the Bluetooth transmission delay.

That kind of issue on the encoder OR player side would've been easily caught in testing, including through automated tests, so as crazygringo says, it's most likely your OS/hardware.

If you need to troubleshoot sync issues, this is a helpful tool: https://www.youtube.com/watch?v=HD4emXqHCsE

that's pretty good, bip bop, those line up spot on. I wonder if its quality/resolution dependent. That test video is 360 max. Whatever I'm perceiving if I'm actually seeing something is in the ms range, it's not obvious it's like right on the border if I trust my senses.

grab the audio stream from something else and stitch them together with ffmpeg (like youtube-dl and others do)

Only some formats which I guess are to be used with older browsers contain both video and audio. In general, these days video and audio are delivered through separate streams on YouTube.