What to feed the HT5000 RGB or YcbCr444 or 422 - AVS Forum
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post #1 of 14 Old 07-15-2008, 06:51 AM - Thread Starter
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I have many choices to output HDMI into the HT5000 and was wondering which Color Space would be Best.


Choice 1

From the Axonix Media Deck I can run either RGB or YcbCr444, and would run Pixel for Pixel @ 1080P24 into the Ht5000. I also could run 1080I or 1080P and let the HT5000 process the signal to 1080P60 again at either color Space.

Choice 2

Much more complicated. From the Axonox I can run 1080I60 either RGB or YcbCr444 into my Radiance XD, and output 1080P60 to the HT5000 either at RGB, YcbCr444, or YcbCr422 @ 1080P60 Pixel ofr Pixel.


So Basically trying to understand which color space would work best into the Ht5000 based on what/how it is being fed.
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post #2 of 14 Old 07-15-2008, 09:36 AM
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The basic consideration is that all digital sources are YCbCr and the final format that goes to the DMDs is RGB. You have to decide if the YCbCr to RGB conversion is best done by the source component, the video processor, or the projector. This is an easy conversion with well defined conversion formulas, but that's no guarantee that it will be done right.

There are additional considerations with specific units. For example, the Pioneer HD1 BD player converts to RGB in the decoder\\processor IC. If you select YCbCr output, RGB is converted to YCbCr by the HDMI transmitter. You now have multiple conversions and that's a potential problem. It's better to select RGB output with this player, unless you are using a video processor that works in YCbCr, which also can add an unwanted conversion.

Another thing to consider is bit depth. YCbCr can offer more bit depth and whether it's needed or not depends on the type of processing before output.

I know that I did not answer your specific question. I don't know enough about your components to do that, but if I had to guess I would say use YCbCr 4:2:2.
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post #3 of 14 Old 07-15-2008, 12:24 PM - Thread Starter
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Thank you Odyssey you answered my question perfectly
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post #4 of 14 Old 07-22-2008, 07:32 AM
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According to JP at Lumagen, YCbCr at 4:2:2 is the preferable output for the HDMI out Lumagen. I note that my inputs intothe lumagen (mostly HD DT) read 4:4:4 in. despite steve's comments, I really have no great understanding of this particula subject but I go to knowledgeable industryfolks such as JRP to get the answers. for example, i really have no clue as towhether convering from 4:4:4 to 4:2:2 has any negatives or not. Intuitively I thinkmany users of the Lumagen would select 4:4:4 thinking it was a higher somethig and thus better. I wanted to find out from Lumagen ans was surprised the answer was 4:2:2. I didn't ask why. But I did switch my personal unit to 4:2:2. I really didn't notice much difference.

Odyssey gave a very knowledgeable answer. Of course finding the right answer in Lon's case because of the many elements and possibilities in his very fine system would depend on very subjective and difficult observations. When i am there next, perhaps we can do some A/Bs just between 4:4:4 and 4:2:2 out on his lumagen using some different sources.

The picture is so damn good, one just wants to watch rather than playing though.

Lon's room, which I didn't build, is so nice I just want to enjoy it.

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post #5 of 14 Old 07-22-2008, 09:50 AM - Thread Starter
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Thanks Mark, I think it really comes down to one simple question, which piece of equipment does the best conversion from YCbCr to RGB the Lumagen Radiance or the HT5000.

I think I recall that what JP actually said was some projectors can not accept RGB without first converting it back to YCbCr and then back to RGB, in that very instance he suggested outputting YCbCr from the Radiance. I believe the projector he spoke about was the JVC Rs1.
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post #6 of 14 Old 07-29-2008, 11:14 PM
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I have a DirecTV HD Plus DVR connected via HDMI to my Lumagen Radiance, then via HDMI to my Sim2 C3X 1080.

The Radiance info menu tells me the video nature (YCbCr 4:2:2 or 4:4:4, or RGB) which is output from the source into the Radiance, and output from the Radiance into the projector. And ouf course the projector info always shows RGB meaning conversion if and as necessary to RGB in the projector.

YCbCr clearly looks better to me from the Radiance to the projector.
Subjectively I thought of saw that 4:4:4 looked a bit better than 4:2:2 but mebbe I was expecting that. Gotta try again.

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post #7 of 14 Old 07-30-2008, 06:17 AM - Thread Starter
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Steve:

On the Ht5000 if it receives YCbCr it states it in the info menu same with RGB, so you are not outputting YCbCr from the Radiance you are still outputting RGB.
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post #8 of 14 Old 07-30-2008, 06:56 AM
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Quote:
Originally Posted by LJG View Post

Steve:

On the Ht5000 if it receives YCbCr it states it in the info menu same with RGB, so you are not outputting YCbCr from the Radiance you are still outputting RGB.

On my C3X 1080 it states RGB in the info menu regardless of whether the Radiance shows that its set to output YCbCr or RGB. I'll take another look to verify this later today.

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post #9 of 14 Old 07-30-2008, 11:09 AM
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From the C3X 1080 manual re the info button:

"Displays the current status of the projector and information concerning the projected video/graphic signal. This function is displayed on pressing the key on the remote control (or, in the absence of the On Screen Display, the ▶ key on the keypad)."

The projected image from the projector will always be RGB. If the projector needs to convert to RGB, it does so. Even if the source feed to the projector is component the info screen will show RGB because that's what is projected.

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post #10 of 14 Old 07-30-2008, 11:13 AM - Thread Starter
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Not so for the HT5000, I send it YCbCr 1080P24 from Bluray and that is what is displayed when I hit the info key
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post #11 of 14 Old 07-31-2008, 07:31 PM
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Here's the advise that I got from Randy Freeman on the Lumagen forum:



"Even if the DirecTV box is outputting YCbCr 4:4:4 the originally source is at best 4:2:2. So there is no advantage to having a video source output YCbCr 4:4:4. Internally the Radiance is 4:2:2. If you set the output of the Radiance to 4:2:2 you will preserve blacker-than-black and whiter-than-white details, but on a well calibrated display you probably won't see any difference using YCbCr 4:2:2 or RGB."

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post #12 of 14 Old 08-01-2008, 06:50 AM
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Steve. months ago i talked toJRP and he recommended setting the the Lumagen to 4:2:2 for best results. That is where I set mine and recommend my customers to set theirs. think intuitivelymany assume a higher number, 4:4:4 would be better. That's why i assumed initially. I went to the expert and resolved this long ago. Really though, i am not sure if I can see any difference but i am not looking anymore. I just leave it at 4;2:2.

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post #13 of 14 Old 08-01-2008, 07:33 AM
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Quote:
Originally Posted by mark haflich View Post

Steve. months ago i talked toJRP and he recommended setting the the Lumagen to 4:2:2 for best results. That is where I set mine and recommend my customers to set theirs. think intuitivelymany assume a higher number, 4:4:4 would be better. That's why i assumed initially. I went to the expert and resolved this long ago. Really though, i am not sure if I can see any difference but i am not looking anymore. I just leave it at 4;2:2.

That is what I am doing now. You posted this above in this thread. So I thought I'd doublecheck on the Lumagen User Forum. As always, you are correctamundo. Thanks.

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post #14 of 14 Old 08-01-2008, 01:20 PM
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More info from Randy Freeman at the Lumagen User Forum:

"HD-DVD and Blu-ray use 8-bit 4:2:0 1080p24 for data storage.
DVD uses 8-bit 4:2:0 480i for data storage.

The Lumagen will get all the data if you set the video source to output YCbCr 4:2:2."

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