WDTV Forum - WDTV Media Player

WDTV 1 Forum Groups => ** Bug Reports ** => Topic started by: Hokeysmoke on May 07, 2009, 01:08:44 PM

Title: BUG v1.02.11 Color decoding is wrong most of the time
Post by: Hokeysmoke on May 07, 2009, 01:08:44 PM
If you go to the bottom of this web page you can see what incorrect color decoding looks like.
http://www.sigmadesigns.com/public/Support/chromaticity.html

Videos are almost always encoded using component video (YCrCb) in order to save space compared to RGB.  Therefore, in order to be displayed the component video must be decoded back into RGB.  The decoding standard for Standard Definition sources such as DVDs is known as BT.601 and the one for HDTV is BT.709.  Therefore, you would expect the WDTV to decode HDTV video files using BT.709 unless told otherwise by flags in the source file.  However, it does not.  It uses BT.601.

The actual behavior is as follows:
If the video file is flagged as BT.601, then it will be decoded using BT.601.
If the video file is flagged as BT.709, then it will be decoded using BT.709.
If the video file is not flagged, then it will be decoded using BT.601.

Unfortunately, most video files are not flagged.  Since almost all HDTV content is made using BT.709, then most of these files will be decoded incorrectly.

The above behavior is correct if this product were a DVD player, but almost all Blu-ray, HD-DVD, and ATSC set-top boxes act differently.  They assume that all HD content is BT.709 unless the flags say otherwise.

Note that this error in decoding occurs internally before the signal even gets to the HDMI transmitter.  So you cannot fix it at the display.
Title: Re: BUG v1.02.07 Color decoding is wrong most of the time
Post by: Monkeyface66 on May 07, 2009, 03:12:38 PM
On the "feature requests voting site" the WD Team accepted this feature request :


"Black level and HDMI color space options in the settings menu to adjust picture quality"

http://wdtv.uservoice.com/pages/17442-general/suggestions/182951-black-level-improved



Maybe the issue with the wrong BT.601 color will be coincidentally fixed then .......
Title: Re: BUG v1.02.07 Color decoding is wrong most of the time
Post by: Hokeysmoke on May 07, 2009, 04:44:11 PM
Unfortunately, these are two separate issues.  The color decoding issue is happening in the Sigma Designs chip, and the black level issue is happening in the HDMI transmitter.  But one can always hope...
Title: Re: BUG v1.02.07 Color decoding is wrong most of the time
Post by: Hokeysmoke on May 07, 2009, 07:30:05 PM
By the way, this bug is not exclusive to the WDTV.  It also affects the NMT products, and I have reported that bug to Syabas as well.  It would be interesting to see who fixes it first.

(Yes, I do have both products now)
Title: Re: BUG v1.02.08 Color decoding is wrong most of the time
Post by: Hokeysmoke on May 28, 2009, 10:38:27 AM
This is still not fixed in 1.02.08.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on June 17, 2009, 11:40:50 AM
This is still not fixed in v1.02.10.  Updated thread title.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: GuyWD on June 26, 2009, 01:35:22 PM
Hi Hokeysmoke, can you please send me a link to an untagged file that reproduces this issue? I would appreciate it.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on June 29, 2009, 09:38:43 AM
Go to http://www.spectracal.com/downloads.html and download the AVCHD version.  This is a suite of test patterns called AVS HD 709 and the one I linked to is the version 1.2b (at least as of this morning) which is unflagged.  The file is a DVD UDF .iso file.  The file with all of the color decoding patterns is 00005.m2ts.  You can copy that directly to the WDTV and it will play fine.

The newer version is 1.3 and is flagged for BT.709, and can be found here: http://www.avsforum.com/avs-vb/showthread.php?t=948496

You can use a green filter with any of the color bar or decoder patterns to see that the color brightness of green is too high, or you can directly see the green brightness problem using the color brightness ramp pattern which is about 6 minutes into the clip.  In the unflagged version the top two green bars are clipped no matter how you set the display's contrast control, which indicates a problem in the YCbCr conversion to RGB.

Let me know if you need any more information.  I also have some MPEG2 files that I made myself with various flag settings.  I'd be happy to send them to you.

By the way, of the 34 HD-DVD and Blu-Ray discs I checked, only 8 or 24% had BT.709 flagged.  So the WDTV would decode the colors incorrectly the vast majority of the time.  Also, about 50% of the off-air ATSC recordings I have are unflagged.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 01, 2009, 03:29:15 PM
Here's some more information that may be helpful.  Since both the NMTs and the WDTV suffer from the same color space conversion issue, I've linked below two threads from the NMT forums.  There is a lot of useful discussion from myself and others, including a successful attempt by a developer on another platform to write an application to test the issue.  Not everything is pertinent, but the root cause probably is the same on both products.

http://www.networkedmediatank.com/showthread.php?tid=19366
http://www.networkedmediatank.com/showthread.php?tid=20381
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: sparky909 on July 02, 2009, 12:10:20 AM
Hi,

Just a quick note - anyone know if this issue occurred in earlier versions of firmware also? e.g. 1.02,1.03...etc...?
Im on old firmware and wondering if its a dealbreaker for upgrading to v10firmware.

many thanks! sparks
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 02, 2009, 07:29:46 AM
Since this is a bug in the default behavior of the SDK from Sigma Designs, it is likely to have existed from day one.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: khkg on July 02, 2009, 12:00:06 PM
Is there any simple way to properly tag my .MKV collection for 709?
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 03, 2009, 03:51:03 PM
I know of no easy way to modify the colorimetry flags without remastering.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: khkg on July 06, 2009, 01:43:09 PM
I know of no easy way to modify the colorimetry flags without remastering.

Darn.  Not hopeful that this is going to be resolved anytime soon by either WD or Sigma.
 
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 15, 2009, 03:51:18 PM
Here's a link to a file that also shows the problem.  Every second it switches from BT.709 flagged to unflagged.  Anyone, even with a completely incorrectly calibrated display, should be able to see the difference.  The correct colors only appear when the "BT.709 Settings" image is displayed.

http://www.cypheros.de/files/Testbild_colour_description_alternating_120sec.ts
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: GuyWD on July 16, 2009, 12:34:20 PM
Thank you.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: khkg on July 21, 2009, 11:37:01 AM
Hokeysmoke:  What programs are you using to see if files are properly flagged or not?
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: GuyWD on July 21, 2009, 02:57:25 PM
Hokeysmoke, can you please post a BT.601 flagged video as well?
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 21, 2009, 08:17:13 PM
Here is a 7z archive of 3 1080p23.976 MPEG files.  They are all identical except for the flags.  They are color bar patterns against a reference gray background.  The top bars are encoded with BT.601 values and the bottom bars are encoded using BT.709 values.  When decoded properly, the brightness of the colors will match the brightness of the gray background.  Typically this is easiest to see using color filters, although you can also just visually compare them against each other to figure out how they're being decoded.

cscmatrix1080p23.m2v is unflagged
cscmatrix709flag1080p23.m2v is flagged BT.709
cscmatrix601flag1080p23.m2v is flagged BT.601

I needed to use 7z archiving to fit the attachment into the limitations of this forum.  7z is open source and I use 7-zip from 7-zip.org to compress and decompress these files.
Title: Re: BUG v1.02.10 Color decoding is wrong most of the time
Post by: Hokeysmoke on July 21, 2009, 09:40:07 PM
Hokeysmoke:  What programs are you using to see if files are properly flagged or not?

To detect the flags I use DGIndex for MPEG files, h264_parse for h.264 files, and vc1_info for VC-1 files.  For VC-1 and H.264 files I generally create a file with TSMuxer using only the first 10 seconds of the video.  This makes the process much faster.
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: Hokeysmoke on October 01, 2009, 06:53:28 PM
This is still not fixed in v1.02.11.
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: robin of the greenwood on October 13, 2009, 04:28:51 PM
Does anyone know if the new WDTV Live suffers from the color decoding error that effects the original WDTV?
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: wiiBox on October 17, 2009, 05:19:08 AM
Does anyone know if the new WDTV Live suffers from the color decoding error that effects the original WDTV?

If it does, that's the least of it's problems in terms of video quality.  On the Live, video playback has lost all it's life compared to the original wdtv.  Everything looks quite drab, especially in shadowed faces.  Some searching revealed it seems I'm not the only one.  I've only had it for a day or so but my experience shows a few glaring problems with PQ.  The one I mentioned earlier and one that seems to show up only on certain videos.  Sort of a grid artifact that shows up during certain colour transitions in the recorded video.  But definitely not there on wdtv1 when I had tested it.  And SD content specially suffers from soft edges.  It's not a huge difference and will probably be fixed once they get that grid bug and fix the decoding engine where most of these bugs probably originate.

I wonder if wdtv1 was anything like this at launch, and I don't know if I want to find out how long it took to get it to where it is now.  I mean, it's only in the last month or so that wdtv1 gained idx/sub support, and not very good support, at that.  Granted, it's not officially listed.

Anyways, I guess I'm saying, if you're at all picky about your AV equipment, you're in a world of hurt when it comes to media players.  Personally, I don't know how I'm supposed to keep the Live unit when video looks so dreadful on it.   ???
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: wiiBox on October 18, 2009, 02:43:00 PM
After some more time it seems I may have over-stated my case.   ::)

The grid patern turned out to be Tversity was transcoding mkv files on me.  For some reason, I thought upnp/dnla apps and devices were supposed to comunicate and exchange info, and in this case, transcode only when needed.

The other observations were from memory since I returned my wdtv1 right after I got the Live.  In retrospect, and for the sake of curiosity, maybe I should have compared them side by side before returning it.  However, I was able to compare the Live output to my Xbox 360 (something I did with the wdtv1, too) and I have to say the differences are about the same.  I still think the Live output is a bit drab and may end up getting a tweaking before it's too long.

(edit: glaring spelling mistake!)
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: khkg on October 18, 2009, 07:43:13 PM
Does anyone know if the new WDTV Live suffers from the color decoding error that effects the original WDTV?

Does anyone know of *any* media players that don't suffer from this issue.  I've sadly taken to converting my .mkvs to Xbox360 compatible format  :(
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: wiiBox on November 06, 2009, 02:48:41 PM
Does anyone know if the new WDTV Live suffers from the color decoding error that effects the original WDTV?

Does anyone know of *any* media players that don't suffer from this issue.  I've sadly taken to converting my .mkvs to Xbox360 compatible format  :(

Actually, on the 360 you can manually choose the component colour space.  I guess you can use that as a work-around.  It's under display settings.

OT:  I finally got around to testing some of those test files and since no one has mentioned it, I can confirm that the WDTV Live does suffer from this problem.  The alternating test file lights up like a xmass tree!

Odd how on the computer the colour ramps don't even blink.  Ah, the weird and wacky world of video.  You learn something new every day!  It took me a while to get my head around the whole black level thing!  It seemed perfectly straight forward at first glance, but it was not.

PS: I know it's a relatively old thread but any update would be greatly appretiated.  Especially from GuyWD!   ::)
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: khkg on November 15, 2009, 09:12:58 PM
Bump for color decoding justice.

Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: Hokeysmoke on January 23, 2010, 09:03:27 AM
Odd how on the computer the colour ramps don't even blink.  Ah, the weird and wacky world of video. 

I don't know about the software player you're using, but PowerDVD 7.3 always uses BT.601 no matter what the flag reads.  This makes the test file stable, but wrong all of the time.  So the test file is not the only thing you should check to make sure your player is working right.
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: wiiBox on January 23, 2010, 08:39:44 PM
Odd how on the computer the colour ramps don't even blink.  Ah, the weird and wacky world of video.

I don't know about the software player you're using, but PowerDVD 7.3 always uses BT.601 no matter what the flag reads.  This makes the test file stable, but wrong all of the time.  So the test file is not the only thing you should check to make sure your player is working right.
Hey Hokeysmoke!

I hear what you're saying, my player seems to detect by resolution and I can manually switch back and forth between sd and hd colour space.

BTW, have you tried the patch for your NMT?  Is it out to the public or still in beta?

Also, do you know if Realtek players also suffer from this problem?
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: Hokeysmoke on January 24, 2010, 09:00:57 AM
have you tried the patch for your NMT?  Is it out to the public or still in beta?

Also, do you know if Realtek players also suffer from this problem?

The patch is not even in beta yet, although a few people are trying it out.  Syabas suggested that it could be ready in about a week.

The XTreamer, which is Realtek player, apparently does not suffer from this issue at all, although it uses BT.709 for all HD files.  This is certainly preferred to using BT.601 most of the time.
Title: Re: BUG v1.02.11 Color decoding is wrong most of the time
Post by: wiiBox on August 18, 2011, 05:02:57 PM
Just thought I'd update this thread.

In all fairness to WD--people reading this thread might come away with the impression this problem persists--this problem has been fix for a while now.  Keep your firmware up to date and you should be fine.