Thanks Bill. I was just talking to somebody today about how I would like to find some WTW stuff on these HD DVDs. I'll take a look at those on one of my projectors when I get some time.
--Darin
--Darin
What clipping looks like in the real world
In discussing the HD-A1, many people do not seem to understand what is meant when reviewers and more knowledgeable AVSers talk about clipping blacker-than-black (BTB) and whiter-than-white (WTW). Some talk about this as a color decoder error. This is not actually correct since this occurs in the digital HDMI output, and not in the analog outputs. The relevance, though, is whether or not we can see it.
But first, a word from our sponsor: those interested in a very detailed discussion of BTB and WTW and how it shows up in images should wander over to the calibration forum (or the DVD forum), and there, in all its glory, are several posts by Chris Wiggles amalgamating some great pieces of wisdom from some of the true men of folklore at AVS. I highly encourage people to read the WTW/BTB discussion linked by Chris to an exchange between Stacey Spears and Don Munsil and several AVSers. It is very enlightening.
http://www.avsforum.com/avs-vb/showt...postid=4969789
Now, back to our regularly scheduled program...
Let's start with something basic, like a grayscale ramp. Conveniently, I have just such a disc handy (yes, I have not yet learned how to do good screenshots):
http://www.datapopuli.com/ht/hd-a1/menu.jpg
When we zoom in on the WTW end of the ramp, we can clearly see a difference between the reference white (digital 235) and the WTW data.
http://www.datapopuli.com/ht/hd-a1/ramp_comp.jpg
However, over HDMI, anything above 235 becomes a hash. There is no differentiation of values there:
http://www.datapopuli.com/ht/hd-a1/ramp_hdmi.jpg
Before people accuse me of rigging the test by blowing out my contrast on HDMI, what you will notice about my display (Optoma H77 projecting onto a 77" wide Da-Lite High Power) is that the analog component and HDMI shots look very different. The two inputs were calibrated to within 4 dE of D65 about 300 hours ago. However, I have recently added both the HD-A1 AND a Lumagen scaler into my signal chain (HDMI->Lumagen->H77 DVI; analog component->H77), and I have not re-calibrated since (having too much fun watching movies...). As a result, what you should look at are the details in the images, rather than trying to compare colors across. Believe me,once the new car smell wears off of the HD-A1, I will have some fun nights with my Spyder and my EyeOne recalibrating with the HD-A1.
That being said, let's take a look at why I think Serenity may have some leg as a reference disc. With everyone focused on the BTB ("lets look at stars") end of the spectrum, I think they are ignoring where we can see real detail loss in an actual movie.
In the first clip, we see that Miranda is made out of textured white concrete. There is a vertical seam in the concrete on a line with Summer Glau's right arm.
http://www.datapopuli.com/ht/hd-a1/miranda1.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda1_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda1_h.jpg
The difference in the crispness of the lines is a result of the superior deinterlacing and scaling being done by the Lumagen Vision HDP using the HDMI output from the HD-A1 vs. the processing being done by the H77 on the analog component signal. While interesting, this is not relevant for the clipping demonstration (this is the best demo I could put together in a short timeframe!).
In the second image, we see another concrete seam, but this time it is on the ground behind Sean Maher (Simon's) back (it looks like a diagonal blue smudge in the analog component shot).
http://www.datapopuli.com/ht/hd-a1/miranda2.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda2_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda2_h.jpg
Finally, we have the scene that was much more clear when I was able to watch the movie in as complete of darkness as my living room gets. You can just barely make out a bit of a difference between where the wall meets the ground. This is perhaps a pretty good test for the folks with bat caves to show off how much better their instantaneous CR is than those of us with white ceilings and light blue and beige walls (the wife picked the colors).
http://www.datapopuli.com/ht/hd-a1/miranda3.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda3_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda3_h.jpg
All that being said, I like the cleaner look of the HDMI picture, but there seems to me to be real information being lost (I have demonstrated this to the best of my meager abilities). Serenity seems to be a good demonstration here because there appears to be a lot of WTW information given how blown out the whites are in the scenes on Miranda.
Later,
Bill
But first, a word from our sponsor: those interested in a very detailed discussion of BTB and WTW and how it shows up in images should wander over to the calibration forum (or the DVD forum), and there, in all its glory, are several posts by Chris Wiggles amalgamating some great pieces of wisdom from some of the true men of folklore at AVS. I highly encourage people to read the WTW/BTB discussion linked by Chris to an exchange between Stacey Spears and Don Munsil and several AVSers. It is very enlightening.
http://www.avsforum.com/avs-vb/showt...postid=4969789
Now, back to our regularly scheduled program...
Let's start with something basic, like a grayscale ramp. Conveniently, I have just such a disc handy (yes, I have not yet learned how to do good screenshots):
http://www.datapopuli.com/ht/hd-a1/menu.jpg
When we zoom in on the WTW end of the ramp, we can clearly see a difference between the reference white (digital 235) and the WTW data.
http://www.datapopuli.com/ht/hd-a1/ramp_comp.jpg
However, over HDMI, anything above 235 becomes a hash. There is no differentiation of values there:
http://www.datapopuli.com/ht/hd-a1/ramp_hdmi.jpg
Before people accuse me of rigging the test by blowing out my contrast on HDMI, what you will notice about my display (Optoma H77 projecting onto a 77" wide Da-Lite High Power) is that the analog component and HDMI shots look very different. The two inputs were calibrated to within 4 dE of D65 about 300 hours ago. However, I have recently added both the HD-A1 AND a Lumagen scaler into my signal chain (HDMI->Lumagen->H77 DVI; analog component->H77), and I have not re-calibrated since (having too much fun watching movies...). As a result, what you should look at are the details in the images, rather than trying to compare colors across. Believe me,once the new car smell wears off of the HD-A1, I will have some fun nights with my Spyder and my EyeOne recalibrating with the HD-A1.
That being said, let's take a look at why I think Serenity may have some leg as a reference disc. With everyone focused on the BTB ("lets look at stars") end of the spectrum, I think they are ignoring where we can see real detail loss in an actual movie.
In the first clip, we see that Miranda is made out of textured white concrete. There is a vertical seam in the concrete on a line with Summer Glau's right arm.
http://www.datapopuli.com/ht/hd-a1/miranda1.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda1_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda1_h.jpg
The difference in the crispness of the lines is a result of the superior deinterlacing and scaling being done by the Lumagen Vision HDP using the HDMI output from the HD-A1 vs. the processing being done by the H77 on the analog component signal. While interesting, this is not relevant for the clipping demonstration (this is the best demo I could put together in a short timeframe!).
In the second image, we see another concrete seam, but this time it is on the ground behind Sean Maher (Simon's) back (it looks like a diagonal blue smudge in the analog component shot).
http://www.datapopuli.com/ht/hd-a1/miranda2.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda2_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda2_h.jpg
Finally, we have the scene that was much more clear when I was able to watch the movie in as complete of darkness as my living room gets. You can just barely make out a bit of a difference between where the wall meets the ground. This is perhaps a pretty good test for the folks with bat caves to show off how much better their instantaneous CR is than those of us with white ceilings and light blue and beige walls (the wife picked the colors).
http://www.datapopuli.com/ht/hd-a1/miranda3.jpg
Analog: http://www.datapopuli.com/ht/hd-a1/miranda3_c.jpg
HDMI: http://www.datapopuli.com/ht/hd-a1/miranda3_h.jpg
All that being said, I like the cleaner look of the HDMI picture, but there seems to me to be real information being lost (I have demonstrated this to the best of my meager abilities). Serenity seems to be a good demonstration here because there appears to be a lot of WTW information given how blown out the whites are in the scenes on Miranda.
Later,
Bill
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Is this SD-DVD calibration disc? If so, the standard for SD-DVD NTSC has a "white" limit of 100IRE or 235 and this is correct.
...Angelo
...Angelo
Quote:
Angelo - You are misinformed. The RGB excursion for both SD and HD is 1 - 254, with reference black at 16 and reference white at 235. I can't send you the Recs, since they are copyrighted, but I can tell you that you can download three of them for free from the ITU just for registering. Thus, you can get a bonus Rec while researching 601 and 709.
That being said, the DVI input for HD on my H77 was calibrated from test patterns I created and fed directly from my HTPC at 720p.
Later,
Bill
| Originally Posted by angelo913 Is this SD-DVD calibration disc? If so, the standard for SD-DVD NTSC has a "white" limit of 100IRE or 235 and this is correct. ...Angelo |
That being said, the DVI input for HD on my H77 was calibrated from test patterns I created and fed directly from my HTPC at 720p.
Later,
Bill
Bill,
Is the clipping you point out endemic to HDMI or is it a problem just for the HDMI output from the HD-A1?
Thanks,
Grant
Is the clipping you point out endemic to HDMI or is it a problem just for the HDMI output from the HD-A1?
Thanks,
Grant
Can a firmware update correct the HDMI issue and will Toshiba provide it?
Quote:
As I understand it, the clipping occurs in the conversion of the YCbCr 4:2:0 data on the disc to YCbCr 4:4:4 for output. If Toshiba offers an upgrade to allow YCbCr 4:2:2 output it should eliminate the clipping.
| Originally Posted by DavidHir Can a firmware update correct the HDMI issue and will Toshiba provide it? |
Bill, thanx for the explaination and screen shots.
Just curious though, your component greyscale look really hot (blue) comparred to the HDMI what looks about right (if anything a little cold). If this a function of the camera or projector calibration?
Just curious though, your component greyscale look really hot (blue) comparred to the HDMI what looks about right (if anything a little cold). If this a function of the camera or projector calibration?
Mossimo N,
He hasn't had time to do a recalibration to reflect the new chain of toys (HD-A1 and Lumigen scaler).
He hasn't had time to do a recalibration to reflect the new chain of toys (HD-A1 and Lumigen scaler).
clipping sucks, that is certain
I am using the HDMI output into a Iscan VP30 and out from the Iscan VP30 via DVI, no clipping whatsoever
I think feeding the video processor the unconverted image (HDMI to HDMI) is the key there
-Gary
I am using the HDMI output into a Iscan VP30 and out from the Iscan VP30 via DVI, no clipping whatsoever
I think feeding the video processor the unconverted image (HDMI to HDMI) is the key there
-Gary
Quote:
Exactly. For this demonstration, what you want to focus on are minute details within the images that are different, rather than the colorimetry (sorry! I know it is distracting).
Caveats for this comparison:
Given all of the challenges facing the Component input, the additional details are still there to be seen (use my time codes on your own sets).
Quote:
Gary - when you put up a test pattern with WTW data (NOT AVIA), do you see the data that is supposed to be missing? Also, I thought you were using a CRT projector, is that not the case for your HD-A1?
Later,
Bill
| Originally Posted by Neuromancer Mossimo N, He hasn't had time to do a recalibration to reflect the new chain of toys (HD-A1 and Lumigen scaler). |
Caveats for this comparison:
- New toys on top of an aging calibration
- Compact camera optics which aren't the best (barrel distortion when the zoom is engaged)
- Different scaling paths for the two inputs (the HDMI into the Lumagen is clearly superior)
- Room reflections that absolutely KILL ANSI/Instantaneous CR
- Etc.
Given all of the challenges facing the Component input, the additional details are still there to be seen (use my time codes on your own sets).
Quote:
| Originally Posted by Gary Murrell I am using the HDMI output into a Iscan VP30 and out from the Iscan VP30 via DVI, no clipping whatsoever |
Later,
Bill
Quote:
This is what Stacey Spears has said, and I, for one, am hoping he is correct (no doubt, really).
| Originally Posted by Josh Z As I understand it, the clipping occurs in the conversion of the YCbCr 4:2:0 data on the disc to YCbCr 4:4:4 for output. If Toshiba offers an upgrade to allow YCbCr 4:2:2 output it should eliminate the clipping. |
Quote:
Get a HD-DVD calibration disc test it again, I doubt the clipping will happen. I've created DVDs of family events since 1999. I encode MPEG2 using Canopus' ProCoder 2 that has the ITU-R BT.601 standard, which apply to all my videos.
Quote:
Yes you can exceed the limits of the 601 but that is not correct for 601 NTSC SD Boardcasting.
As for the 709 standard for HDTV, haven't used it as I'm still shooting and editing SD.
But even if the HD player is upscaling the resolution of a SD DVD, I would not expect the HD player to convert the 601 SD DVD colour space to 709; if that's what you're suggesting?
..Angelo
| Originally Posted by Ursa Angelo - You are misinformed. The RGB excursion for both SD and HD is 1 - 254, with reference black at 16 and reference white at 235. I can't send you the Recs, since they are copyrighted, but I can tell you that you can download three of them for free from the ITU just for registering. Thus, you can get a bonus Rec while researching 601 and 709. That being said, the DVI input for HD on my H77 was calibrated from test patterns I created and fed directly from my HTPC at 720p. Later, Bill |
Get a HD-DVD calibration disc test it again, I doubt the clipping will happen. I've created DVDs of family events since 1999. I encode MPEG2 using Canopus' ProCoder 2 that has the ITU-R BT.601 standard, which apply to all my videos.
Quote:
| YCbCr is defined by the ITU-R BT.601 standard. The range of luminance is 16 to 235 and the chrominance range is 16 to 240. |
As for the 709 standard for HDTV, haven't used it as I'm still shooting and editing SD.
But even if the HD player is upscaling the resolution of a SD DVD, I would not expect the HD player to convert the 601 SD DVD colour space to 709; if that's what you're suggesting?
..Angelo
Quote:
I hope you are right as well... however it is not killing me right now, it is light years better than tons of macroblocking and aftifacting that i was used too... I hated grey scenes in movies before i upgraded the firmware for my s97 it was pink skys all around.. ICK!!
| Originally Posted by Ursa This is what Stacey Spears has said, and I, for one, am hoping he is correct (no doubt, really). |
Angelo - Please look-up the relevant specs, rather than quoting some unnamed source. MANY people, even self-proclaimed experts, get this wrong. You are also wrong.
For 4:2:2 video:
Quote:
The copy I have at work also has 4:4:4 video on it. Shall I quote that here, too?
How about Rec 709?
Quote:
I will not touch your misunderstanding of the conversion between component and RGB video. I will ask that you do your homework and NOT turn this thread into another "BTB/WTW isn't necessary" thread.
Later,
Bill
For 4:2:2 video:
Quote:
| Originally Posted by RECOMMENDATION ITU-R BT.601-4, page 2 9. Code-word usage: Code words corresponding to quantization levels 0 and 255 are used exclusively for synchronization. Levels 1 to 254 are available for video |
How about Rec 709?
Quote:
| Originally Posted by RECOMMENDATION ITU-R BT.709-5, page 12 6.10 Quantization levels(2): 8- bit coding – Black level R, G, B, Y 16 – Achromatic CB, CR 128 – Nominal peak – R, G, B, Y 235 – CB, CR 16 and 240 6.11 Quantization level assignment(3) 8- bit coding – Video data 1 through 254 – Timing references(2) 0 and 255 |
Later,
Bill
How are you using 4:2:2 and 4:4:4 colour samples with this player? Isn't your original source a SD DVD? If so SD MPEG2 uses 4:2:0 colour sample.
...Angelo
...Angelo
Quote:
I actually acquired a VP30 from a friend, but have not yet bothered to hook it up to my Optoma H78. Hopefully I will beable to connect the Toshiba HD-A1 and the VP30 this weekend and see what results I get in terms of TWT and BTB results with and without the processor.
| Originally Posted by Ursa Gary - when you put up a test pattern with WTW data (NOT AVIA), do you see the data that is supposed to be missing? Also, I thought you were using a CRT projector, is that not the case for your HD-A1? |
Quote:
Are you using the ABT1010 and the new beta firmware (April 28)?
| Originally Posted by Gary Murrell clipping sucks, that is certain I am using the HDMI output into a Iscan VP30 and out from the Iscan VP30 via DVI, no clipping whatsoever I think feeding the video processor the unconverted image (HDMI to HDMI) is the key there -Gary |
Quote:
Angelo - Your intransigence is making my brain hurt. The major difference between 4:4:4, 4:2:2 and 4:2:0 is how the conversions work between them. Would you like THAT part quoted at you as well? 
Later,
Bill
| Originally Posted by angelo913 How are you using 4:2:2 and 4:4:4 colour samples with this player? Isn't your original source a SD DVD? If so SD MPEG2 uses 4:2:0 colour space. ...Angelo |
Later,
Bill
Quote:
What is your source for checking for clipping? I have a couple more projectors I can use to test with, but between a friend and I, I think we saw clipping with 2 or 3 projectors. I have DVE and AVIA Pro for DVD, as well as some HD test patterns.
--Darin
| Originally Posted by Gary Murrell I am using the HDMI output into a Iscan VP30 and out from the Iscan VP30 via DVI, no clipping whatsoever |
--Darin
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