24 Hz and 12-bit HDMI deep color mode bug?

[peternissen]

Hi Community,

Trying to minimize jitter and posterization (bands) on my new Panasonic ST60 TV when playing 1080p 24 Hz files on WD TV Live 1. gen (latest official firmware 1.06.43).

However, there seems to be a bug in WD TV Live 1. gen. so that there is no nice way of minimizing both jitter and posterization!

If setting HDMI output to Auto resolution/framerate and selecting to match video framerate to file, the HDMI deep color mode is set back to 8 bit. Only if setting ‘match video framerate’ to off is 12-bit HDMI deep color mode available.

In other words:

• Auto resolution/framerate + match video framerate on => no 12-bit HDMI-deep-color = posterization.
• Auto resolution/framerate + match video framerate off => always 50Hz = jitter in 24Hz files.
• Fixed resolution/framerate (e.g. 1080p24 or 1080p50) => minimize both jitter and posterization, BUT result in jitter in files of other framerates.

Please, can anyone confirm this limitation/bug?

Also, does anyone know if this has improved in later WD TV Live generations?

Thanks in advance for all comments!

PS. Searching the topic I found quite a few comments that 12-bit deep-color has no advantage given the current data format of DVD/BD. This is very wrong. 12-bit deep-color has a considerable improvement on reducing posterization (bands). One post did explain that it is the image decompression (“Inverse” Discrete Cosine Transform) that takes advantage of the higher bit depth.

[richUK]

As far as I remember the 8 bit is deliberate in the auto resolution / framerate mode and not a bug.

I don’t understand your fixed resolution / framerate arguement as obviously the auto framerate will I believe only change to what the TV is capable of.

1080p24 /1080p50 / 1080p60 should cater for the majority of files but you have to do the  change manually.

As your post was specifically about 24Hz and banding surely setting the player to 12 bit and the resolution to 1080p24 will overcome your problem. I assume that when you say a nice way that you would like this to be automatic.

[richUK]

http://community.wd.com/t5/WD-TV-Live-Live-Plus/8Bit-or-12bit/m-p/48783/highlight/true#M12156

The fact is that the source is no more than 8bits so the TV is not getting any more information to make decisions on the color than an 8 bit set.

[peternissen]

Thanks richUK,

If the missing 12-bit option is by design, when choosing to ‘match video framerate’, I would really like to understand the logic behind it:-)

Maybe my fixed resolution/framerate explanation was unclear. But I will only get minimized jitter AND posterization (in 24 Hz) if I force the WDTV to a fixed framerate - as this give me the opportunity the select the 12-bit color depth. As you write the BIG disadvantage of fixed setup is - obviously - that it is fixed and need to be manually changed for varying video files.

When using auto resolution/framerate, and NOT selecting to ‘match video framerate’, then WD TV apparently selects to convert 24 Hz as 50 Hz regardless of the capabilities of the TV. The capability information seems to reach WD TV (have a Denon AVR-3808 receiver inbetween), as selecting to ‘match video framerate’ is honored by WD TV (but again only allowing 8 bit color depth).

(Sorry, ended up with another long explanation - let me know if it made things clearer or not!)

Thanks again!

[peternissen]

richUK,

Reply to your second post and link. 

Not all sure what you are linking to, but the entry from TonyPh12345 makes perfect sense to me. I see great improvements in posterization/bands when outputting 12 bit from WD TV to my TV. And as written by TonyPh12345 the higher bit depth has an advange in the decompression of the video data. I see the improvement both in the shaded blue background of the WD TV screens, and in movies (simple scenes with shades).

Thanks once more for your input.