Fullscreen Youtube dropping frames

[harryfornasier]

I've noticed that when watching Youtube videos in fullscreen it's started to drop a lot of frames. This has always happened with 60fps content. However, this has now started to happen with 480p non 60fps content as well. Has something changed with Youtube recently? I'm using a Mac Pro 2013, which I understand is old but I think it should play 480p without dropped frames. I've also tried to do this in Firefox 78 and I found that I can play 4K 60fps content without any dropped frames. Is there something with the hardware acceleration for videos that's gone weird? Anyone else noticed something like this?

[Wowfunhappy]

If you go to chrome://gpu/, is Video Decode listed as hardware accelerated?

[harryfornasier]

Just as an experiment I downloaded a version 1087030 from 2022 and it can play 1440 at 60fps in fullscreen without any dropped frames. I think something has changed since then to cause this.

[Wowfunhappy]

If you can do a bisect (find the first canary version that's dropping frames, by repeatedly trying the version halfway between the known-working and known-broken version), we might be able to find the problematic commit, or give Bluebox enough information to do so.

[harryfornasier]

Nice, didn't take me too long to do. Last version that was working was 112.0.5615.137.1 and it broke in 1135237

[Wowfunhappy]

Great! Just confirming it's working in build 1130655 as well? We're ignoring stable builds in the bisect as they come from a different branch.

If you know it's down to those two builds, I would make a formal bug report in the issues section. I did some looking through commits myself but with a week in between the two canary builds, there's a bit too much for me to sort through, although I'll look again if I have time.

[harryfornasier]

Ah okay wasn't sure of the difference between them. Yes it was working in that version too. Okay cool i'll make a bug report. Thanks for the help!

[krackers]

@harryfornasier Continuing from #158 (comment)

Can you post the crash output, as well as how you built mpv?

[harryfornasier]

Here's the verbose file for trying to run it.
MPV.zip

[krackers]

unfortunately that doesn't really seem to indicate why it couldn't initialize. Do you have xquartz installed? But either way doing it this way is not going to give a good experience on mac. Maybe you could revert the macports formula to the last version before xquartz was required.

[harryfornasier]

Ah that was it, I didn't have xquartz installed. It can now play local videos, however it still can't play YouTube videos. It complains that I have self-signed certificates in my keychain, so it just crashes.

[krackers]

It complains that I have self-signed certificates in my keychain, so it just crashes.

What's "it" here, there's two separate pieces at play, youtube-dl and ffmpeg. IIRC mpv passes the ignore cert flag by default so it shouldn't be the issue. So is it youtube-dl that's erroring out? There's probably a way to override it if needed.

Btw do you mind posting a screenshot of how mpv looks like running under xquartz, I'm curious.

[harryfornasier]

What's "it" here, there's two separate pieces at play, youtube-dl and ffmpeg. IIRC mpv passes the ignore cert flag by default so it shouldn't be the issue. So is it youtube-dl that's erroring out? There's probably a way to override it if needed.

Ah my bad, I wasn't very clear. It's the ytdl_hook that fails.

Btw do you mind posting a screenshot of how mpv looks like running under xquartz, I'm curious.

Sure, I took short video on my phone. It seems to play just fine from what I can see. Only thing I've noticed is it can't play HDR video or map HDR video to SDR. It also doesn't seem to do proper full-screen, the task bar will always be there.

MPV.mp4

[Wowfunhappy]

Just for the heck of it, I'll share my setup for watching Youtube which uses QuickTime (albeit QuickTime 10.2 from Mountain Lion) instead of a third party video player. The major caveat is you have to download videos wholly instead of incrementally streaming them, but I prefer this because I have a guarantee the video will never buffer or temporarily change quality.

Install this service to download videos: https://jonathanalland.com/downloads/download-video-service-2.dmg (at some point I will put this on m website, but it's currently unlisted.)
Install QuickTime 10.2 and FFusion 2021 from: https://jonathanalland.com/old-osx-projects.html

From now on just go to a web page and run the service.

You may want to set up a keyboard shortcut for the service such as cmd+opt+S in System Preferences. I also added the "Movies" folder to my Dock, set to Sort By: Date Added and View Content As: Fan.

I like using native Apple tools for stuff when I can! It's relatively capable and it keeps the OS experience cohesive.

I also use my "Media Subscription Preferences Pane" so new videos from channels I like are downloaded automatically over night and show up in my downloads folder.

[Wowfunhappy]

There are other things too. Like for example, if you close a video and a Finder window with that video file is also open, the video closes into that icon; this can be legitimately useful for seeing where the file lives. And the fact I can right click QuickTime in the Dock and get a list of my recent files. And I can play/pause videos with the buttons on Bluetooth speakers. And Applescript support, so I can press buttons on my remote to e.g. skip forward or backwards 15 seconds. There is definitely more I'm forgetting.

Maybe mpv can do some of these—I haven't tried it in ages—but these are the types of details I almost never see in cross-platform apps, only ones that are designed to be Mac-native. The features are all trivial in isolation, but they add up.

It's a shame IINA is 10.10+, or I would probably use that instead. But my current setup with QuickTime 10.2 + FFusion works reasonably well. My only real problems are that:

1. mkv files aren't natively supported. My workaround is to open them with a "QuickTime Helper" application which changes the container and hands the result off to QuickTime, but this removes many of the Mac-native advantages I just discussed.
2. Decoding h265 takes a ton of CPU. I can't play h265 at all on my laptop, and I can't smoothly scrub through videos on my desktop. This isn't really specific to QuickTime, but I suspect my hacked-together FFusion decoder is not optimally efficient.

And I guess the fact that I can't stream from Youtube, but as I said I mostly prefer pre-downloading anyway. No bufferring hiccups, and I can scrub through videos quickly if need be.

This isn't a native feature of QuickTime, but I also hacked my version to save the current position of every video I watch, stored against a hash of the video title and its precise duration (number of seconds with ten decimal places). So I can close a file and open it later, and it always seamlessly opens to where I left off, which I absolutely love.

[krackers]

(not sure why my response disappeared first time I posted).

There are other things too.

Yeah that's fair, while it seems like each feature is individually simple enough that it'd be "easy" to add to mpv, at that point you're basically just reimplementing iina.

play/pause videos with the buttons on Bluetooth speakers

There's a thing you can use on osx to remap bluetooth buttons to native media key buttons so it works on all apps without special support. I forgot what it was, it's either a simbl plugin or takes advantage of some obscure feature to intercept bluetooth keypresses.

FFusion efficiency

Did you compile it (and the in-tree ffmpeg) with -O3? By default xcode is only debug, -O0 or something, and release is only -Os. Granted the actual decoder is implemented in assembly anyway but the glue code might be an issue. I can decode 720p h265 content fine on a 2.8 ghz i7, albeit at 70% cpu usage. So it feels like software decoding should be feasible for most laptops. It might just be that FFusion doesn't properly enable multithreaded decoding though, if you're interested in tinkering you could take a look and see to make sure they're setting up the lavc context correctly.

[Wowfunhappy]

Did you compile it (and the in-tree ffmpeg) with -O3? By default xcode is only debug, -O0 or something, and release is only -Os

I remember I tried both -03 or -Os and couldn't see a difference, I don't remember which I went with in the end, but I did set this.

I can decode 720p h265 content fine on a 2.8 ghz i7, albeit at 70% cpu usage. So it feels like software decoding should be feasible for most laptops.

That sounds about right. Key word there is 720p.

My laptop has a dual core Broadwell i7, with a base clock of 1.7 Ghz. I can play the 10 Mbps, 8 bit color test file from https://www.larmoire.info/jellyfish/ (jellyfish-10-mbps-hd-hevc.mkv). It chokes on the 15 Mbps file, and the 10 Mbps file with 10-bit color.

The biggest place this is a problem is iPhone video, which by default is h265, 10-bit, 4K. I can change the settings on my own iPhone but other people use the defaults, and my laptop can't play their recordings.

There seems to be some sort of extra color conversion routine necessary for QuickTime, which I think may be what's stealing CPU cycles: https://github.com/Wowfunhappy/FFusion/blob/master/ColorConversions.c

[krackers]

That seems to be pixel format conversion. I'm not sure if I'm understanding it right though, yuv420 is what I understand is "most" common and should be supported natively by quicktime. But it seems to convert things to yuv422. It also seems to be stuck using sse2, you could rewrite using avx256 which haswell supports. But probably worth profiling first to see where the cpu time is going, or comparing against some known reference (e.g. vlc?)

[Wowfunhappy]

I'm not sure if I'm understanding it right though, yuv420 is what I understand is "most" common and should be supported natively by quicktime.

Should be but I think it isn't, at least not for QTKit. (The newer AVFoundation has no plugin support.)

QTKit is absurdly old. It dates back to Classic Mac OS, and then some... there is boilerplate code in FFusion which references Motorola processors. So it doesn't surprise me that QTKit expects a "weird" pixel format by modern standards.