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Old 19th February 2005, 20:39   #1  |  Link
Spyn
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question about YUV -> RGB

TV Scale uses luminance 16-235 cause a tv is unable to go higher than 235 and lower than 16 or is there another "cause" ?

i want to be sure that TV Scale gives a better quality on a TV screen cause i encode all my movies for watching on a TV.
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Old 19th February 2005, 21:49   #2  |  Link
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It's gonna get clipped either way.
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Old 19th February 2005, 22:49   #3  |  Link
Spyn
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what ?
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Old 19th February 2005, 22:57   #4  |  Link
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Quote:
Originally posted by Spyn
what ?
For watching things on your TV its better to put it into TV scale and even if you don't the output to your TV is going to clamp the luma to TV scale anyway. So there's pretty much no point in using PC scale if you are just gonna watch it on your TV. Of course when you use TV scale you aren't gonna get the blackest of black or the whitest white, but that's just the limitation you gotta live with when watching stuff on TV.
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Old 19th February 2005, 23:02   #5  |  Link
Spyn
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Quote:
Originally posted by KaiserS
For watching things on your TV its better to put it into TV scale and even if you don't the output to your TV is going to clamp the luma to TV scale anyway. So there's pretty much no point in using PC scale if you are just gonna watch it on your TV. Of course when you use TV scale you aren't gonna get the blackest of black or the whitest white, but that's just the limitation you gotta live with when watching on TV.
are you sure about this ?

absolutely no TVs are able to display a range higher than 16-235 ?
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Old 19th February 2005, 23:04   #6  |  Link
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Quote:
Originally posted by Spyn
are you sure about this ?

absolutely no TVs are able to display a range higher than 16-235 ?
I'm pretty sure not cause NTSC uses a luma scale of 16-235. I don't remember what PAL uses but I'm pretty sure its the same.

Last edited by KaiserS; 19th February 2005 at 23:07.
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Old 19th February 2005, 23:05   #7  |  Link
Wilbert
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This setting doesn't do anything when using Mpeg2dec3/DGDecode.
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Old 19th February 2005, 23:15   #8  |  Link
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NTSC is an analog interface. It makes no sense to speak of digital pixel values on the analog interface. The fact of the matter is that YUV is defined to be the clipped ranges. Sending something outside them is an undefined operation. It will likely be clipped somewhere, and if not it may cause artifacts.

Crank up your contrast control, Spyn, if you want more range.
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Old 20th February 2005, 11:37   #9  |  Link
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Quote:
Originally posted by neuron2
NTSC is an analog interface. It makes no sense to speak of digital pixel values on the analog interface. The fact of the matter is that YUV is defined to be the clipped ranges. Sending something outside them is an undefined operation. It will likely be clipped somewhere, and if not it may cause artifacts.

Crank up your contrast control, Spyn, if you want more range.
so i must use PC Scale to don't have any artifacts ?

I don't understand all that you said cause of poor english and knowledge, sorry.
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Old 20th February 2005, 15:24   #10  |  Link
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Sending 0-255 to a device designed to accept YUV ranges *may* cause artifacts, depending on the device.

I can't say it any clearer than that and English is my only language.
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Old 20th February 2005, 17:34   #11  |  Link
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Quote:
Originally posted by neuron2
Sending 0-255 to a device designed to accept YUV ranges *may* cause artifacts, depending on the device.

I can't say it any clearer than that and English is my only language.
so YUV range is 16-235 and RGB is 0-255.

I got a pioneer DV-470 divx player connected to my tv with a SCART connector using RGB mode so i think i can use PC-Scale (0-255) without any artifacts ?

Do you know which range is used by Y/C (S-video) ?

thank's for your answers
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Old 20th February 2005, 17:39   #12  |  Link
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Are you using AviSynth? If so read my response again ...
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Old 20th February 2005, 18:01   #13  |  Link
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Quote:
Originally posted by Wilbert
Are you using AviSynth? If so read my response again ...
why dgecode.dll force 0-255 ?
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Old 20th February 2005, 18:43   #14  |  Link
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No, it doesn't touch the lumarange (ie YUV [16,235]).
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Old 20th February 2005, 19:21   #15  |  Link
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Quote:
Originally posted by Spyn
so YUV range is 16-235 and RGB is 0-255.
Almost. Y range is 16-235. UV range is 16-240.

Quote:
I got a pioneer DV-470 divx player connected to my tv with a SCART connector using RGB mode so i think i can use PC-Scale (0-255) without any artifacts ?
It depends upon what the DV-470 decoder does. Most likely, it will clip to legal ranges.

Quote:
Do you know which range is used by Y/C (S-video) ?
S-Video is an analog interface. Digital pixel value ranges have no meaning there.
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Old 20th February 2005, 21:20   #16  |  Link
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Quote:
Originally posted by Wilbert
No, it doesn't touch the lumarange (ie YUV [16,235]).
i think you wrong,

here is a screenshot of dgindex using pc scale :



dgindex using tv scale :



after loading each d2v file (one using pc scale, other using tv scale) in a .avs and open those avs using vdubmod, here is the result :

.d2v created using pc scale :



.d2v created using tv scale :



both vdub screenshots shown that in all case pc scales is use (0-255)

Last edited by Spyn; 20th February 2005 at 21:22.
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Old 20th February 2005, 21:50   #17  |  Link
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VirtualDub is converting back to PC scale as part of its YV12 decompressing. It always wants to display in the display pane as RGB.

Actually, DGDecode only uses the scale setting in two cases: when you use the extra convert to RGB filters in the DLL, and when a 3rd-party app, such as Gordian Knot or VFAPI, requests an RGB frame. Normally, the served D2V passes out 16-235/240.
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Old 20th February 2005, 23:17   #18  |  Link
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Quote:
Originally posted by neuron2
VirtualDub is converting back to PC scale as part of its YV12 decompressing. It always wants to display in the display pane as RGB.

Actually, DGDecode only uses the scale setting in two cases: when you use the extra convert to RGB filters in the DLL, and when a 3rd-party app, such as Gordian Knot or VFAPI, requests an RGB frame. Normally, the served D2V passes out 16-235/240.
Ahhh, my brain hurts. You lost me with the very last sentence. Here's what I thought I had learned from you and Wilbert:
  • * Scale setting is not used AT ALL unless DGDecode is outputing an RGB frame. Which means DGDecode normally outputs unclamped 0-255 full range. (You indicate DGDecode normally outputs clamped output?)

    * If an RBG frame is output then the scale setting is applied as follows: PC -> 0-255 (unclamped) or, TV -> 16-235/240 (clamped)
This could make a good FAQ clarification.
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Old 20th February 2005, 23:40   #19  |  Link
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using TV Scale or PC Scale will never change anything if i compress in YV12 with vdubmod if i understand, the range will be 0-255.

thank's all

Last edited by Spyn; 20th February 2005 at 23:42.
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Old 20th February 2005, 23:44   #20  |  Link
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Quote:
Originally posted by Spyn
using TV Scale or PC Scale will never change anything if i compress in YV12 colorspace with vdubmod if i understand, the range will be 0-255.
No, YUV has a luma range of 16-235, YV12 is a YUV colorspace. So if the luma range of the video hasn't been put into TV scale before its feed to the codec the codec itself will clip the luma range.

Last edited by KaiserS; 20th February 2005 at 23:51.
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