MPV not working as expected

[ciaens]

Describe the bug
Depending on the configuration, the MPV backend doesn't work, or exhibit color shift, color banding, compression, and fails to display an HDR image.

To Reproduce
Steps to reproduce the behavior:

1. Go to a movie encoded in HEVC 10 bit with HDR10 (main).
2. Click on play
3. See error (black screen or wrong playback).

Expected behavior
Normal playback of the movie, as done with the default backend (Exoplayer).

Screenshots

First image is MPV, second is ExoPlayer. You may need to increase brightness as it was captured on an HDR screen. Very noticeable in person.

Device info (please complete the following information):

• Device: Google Pixel 8 Pro
• Android version: 14 / UQ1A.240105
• App version: v0.13.1 / versionCode 22 / targetSDK 34
• Jellyfin version: not relevant

Additional context
Here are some logs where I start by using MPV, and then switch to ExoPlayer.
In this first log, I'm using first MPV with gpu-next and mediacodec-copy, then ExoPlayer
E dev.jdtech.jellyfin: PIXEL: ioctl err: 1 is spammed during MPV playback. See complete verbose logs below:
Findroid log 8242f4cf56ba.txt

In this second log, I'm first using MPV with no mediacopy / hardware encoding, then switching to mediacodec-copy.
Related issue: #537
When disabling hardware acceleration, I only get a black screen. When using the hardware encoding mediacodec or mediacodec-copy, I have an image (it's not displaying correctly thus why I'm making this issue).
Findroid log 6c1e37110e7e.txt

About this: #574
I've sometime encountered this issue, but this was either weird encoded movies, or solved by clearing the cache of the application.

[Jcuhfehl]

Mpv on android cannot support hdr. This means all playback is tonemapped, which seems to be the cause of the color shift you're describing. The banding might also be because of this, but I'm not entirely sure about that since mpv should dither it when tonemapping

[ciaens]

You're right mpv-android doesn't support HDR (I didn't think of that).
When using the android-mpv application, with the gpu-next backend I don't get the color shift and banding as in Findroid. The file plays in SDR but correctly tonemapped.
Here are the stats of mpv-android to compare:

[jarnedemeulemeester]

The differences between Findroid and mpv-android may be because mpv-android is using a newer version of MPV than Findroid.

The next version of Findroid will upgrade mpv to the latest version (0.37.0) which will hopefully solve the tonemapping issues you're seeing.

And yeah, it's correct that mpv in Findroid has the same limitations (HDR) as mpv-android.

[Jcuhfehl]

@ciaens What video settings do you use in mpv android? Findroid uses mpv's fast profile which leads to lower quality. Can you test if changing your mpv android settings to the following recreates the artifacts you're experiencing:

scale=bilinear
dscale=bilinear
dither=no
correct-downscaling=no
linear-downscaling=no
sigmoid-upscaling=no
hdr-compute-peak=no
allow-delayed-peak-detect=yes

I plan to create a pr to allow switching between mpv profiles (probably also individual settings) because there are a lot of quality improvements to be had from using actually good scaling kernels

[ciaens]

Sure !
Here are the result. The first image is reference (VLC), the second is Findroid, and the third is MPV android with your settings (and gpu-next backend).

When I said MPV was doing dithering great, I only tested on a local HDR 10 film taken with my phone.
As tested with a real media, it seems that it's struggling a bit more, but still better than default Findroid imo.

[Jcuhfehl]

This honestly just looks like different tonemapping methods. Personally vlc (are you sure it's vlc and not exoplayer?) seems worst (it nukes all the stars but I'm not sure because they're not the same frame). Providing more options is basically the only solution, since there isn't a "mathematically correct" way to tonemap so it's always going to come down to subjective opinion

Edit: both vlc and explayer support hdr passthrough, so the first image is also tonemapped (through some unknown process at screenshot time) so me claiming it looks worse probably doesn't make sense

[Jcuhfehl]

@ciaens could you test with #652 (with high quality enabled) and gpu-next to see if you still get the same issue?

[ciaens]

@ciaens could you test with #652 (with high quality enabled) and gpu-next to see if you still get the same issue?

Hello,
I've build your branch of the projet but couldn't find the options in the menu. I do have the options from the other's PRs.

To answer your precedent post, I did crank up the brightness of the image to make the defaults more apparent in a single screenshot. VLC was imo almost perfect, with only occasional decode hiccups. The screenshot I presented was taken with the file paused, and loaded at that frame (it was the 1st frame displayed) so that maybe the cause of visual glitches.

[GrabbenD]

Mpv on android cannot support hdr. This means all playback is tonemapped

Is this just Android or also Android TV?

[Jcuhfehl]

It's an mpv limitation, so it applies to both android and android tv

[Doc-4]

When you ship the next version of Findroid, can you ship it with this sub branch of MPV if possible?

It supports HDR for compatible devices using the flags mentioned in this issue mpv-android/mpv-android#874 (comment)

[foux]

It would be great to have the HDR compatible MPV version

[Doc-4]

Having used it plenty since back then, I'd actually advise shipping it as a separate version or test at first instead, as MPV android vulkan version can't use HW+ (mediacodec-copy) and as a result tends to stutter on large files with high bitrates using HW (this just so happens to be a lot of HDR content), even on powerful devices.