[tvOS] 4K content on 1080p displays stutter and buffer a lot

[parski]

Describe the bug
If you try to play 4K content on an 1080p display on tvOS the video will stutter and buffer a lot. Not sure what to do about it. It also happens in TracyPlayer.

To Reproduce
Steps to reproduce the behavior:

1. Play 4K content.

Expected behavior
I expect the content to play normally.

Screenshots
(I've added a UIActivityIndicatorView to show on KSPlayer.KSPlayerState.buffering)
https://github.com/kingslay/KSPlayer/assets/2445818/6db41a3c-ec98-4c59-a799-b8c0fd089e8c

Platform (please complete the following information):

• Device: Apple TV (4th gen) // This is a 1080p device
• OS: tvOS 17.4
• Version: latest master but the issue has been around since I started playing with this project.

Additional context
I use KSPlayerLayer but it seems to happen on every implementation of these players. I used wired ethernet and have no problem with bandwidth. Playback works perfectly fine on a 4K Apple TV.

[kingslay]

你可以试着在设置-视频里面 把 Use DisplayLayer 设置为false。看下会不会还有这个问题。

[parski]

Setting the option to Off in TracyPlayer makes no discernable difference. Not sure how it's supposed to be set in KSPlayer as the option seems to be a getter only but I'm seemingly able to achieve the same thing through tweaking the logic a bit. Either way, makes no difference.

I've been playing around with altering the CVPixelBuffer but it turns out I have no idea what I'm doing.

Is anyone able to reproduce the problem? I really don't think it's a bandwidth issue. I did a speed test over Wi-Fi which should be my slowest testable speed on this device and I'm getting around 100/100 Mbps. The video I'm testing with (same one as in the original post) has a bitrate between 2-10 Mbps, so well within capacity.

[parski]

It doesn't seem to happen when I set my 4K Apple TV to 1080p output.

[kingslay]

@parski 你可以试着把一个4k的视频片段放到app里面。然后试着进行播放。看会不会有问题。这样就可以排除网络的问题。

[kingslay]

@parski 如果不是网络问题的话，那应该就是解码耗时太久了。那可以试下在设置-视频 把 asynchronous Decompression 设置为true。看下是否有效果。如果还是没有效果的话，那就没有什么好的办法了。这个应该就是硬件的问题，无法顺畅的解码4k的内容。最后你也可以试下mpv或是vlc。看下他们播放4k的内容是不是也会有这个问题。