Incorrect playback of full range luma video

[mawazi 1]

I've discovered that my Deep Space Nine DVD rips contain "whiter-than-white" information, meaning that highlights are not nearly as blown out when taking this into account during encodes. My preferred method is to stretch the normal black point of 16 down to 0, and keep the absolute white point at 255. I then encode this in full range, sometimes known as pc range, or jpeg range. I have properly indicated that the video is full range when encoding with ffmpeg using the -color_range pc parameter (this is with h264).

 

I get correct playback when using the LG app and when using the Chromecast app.

 

When playing the video either on the iPhone or through the Apple TV 4k, something odd happens. I would expect it to fail by incorrectly cutting off the blacks at 16 (rather than 0) and the whites at 235 (rather than 255), crushing the blacks and blowing out the whites, resulting in an artificially high contrast ratio.

 

But instead, it looks like it is compressing the 0-255 range into the space of 16-235, but then displaying it as 0-255, leading to highly elevated black levels (very washed out). It's quite strange. Both the iOS and tvOS apps use mpv now, so something isn't being intrepreted correctly my mpv it would seem. I can play the video correctly using mpv in Windows.

 

I'm not sure in this case what additional information would be useful. Would a piece of the video file help?

 

New information: Stranger, yet. I've discovered that if I pause the playback on my iPhone, 'minimize' the app so that I'm looking at the 'desktop', bring the app back up to fullscreen, the video display switches into the proper mode of showing the entire 0-255 range with 0 being black and 255 being white. No more elevated blacks. Not the best solution in the world, but it does show that mpv is capable of doing the right thing, just not when first playing the video.

Edited May 30, 2019 by mawazi

[Luke 37317]

Hi there, yes can you provide a small sample for testing? Thanks !