PAL HDV to SD Parameters

Lou van Wijhe wrote on 11/4/2008, 6:18 AM
I shoot HDV and put it on BD for my own use. For others I want to downsample to SD in Vegas and put it on DVD. For downsampling I plan to use the "DVD Architect PAL Widescreen video stream" template and customize it as follows:

1. Video rendering quality: Best
2. Field order: Upper field first (to match the HDV field order)
3. Color primaries, etc. all changed to ITU-R Rec. 709 (also to match HDV)

Anything else I should think of?

TIA,
Lou

Comments

Wolfgang S. wrote on 11/4/2008, 9:27 AM
if you use the DVDA template - you should not change the color space at all. In addition to "best", you should also change the quality level to 31. That is the best you can do.
Lou van Wijhe wrote on 11/4/2008, 10:10 AM
Thanks for responding, Wolfgang. One question: If the HDV source is interlaced TFF, wouldn't jitter be introduced when I leave the field order at BFF, as in the DVD template?

Lou
farss wrote on 11/4/2008, 10:15 AM
Vegas will take care of the field order swap, don't mess with the defaults.
What's not been mentioned is you need to specify a de-interlace method in your project. Unless you've got a lot of fast motion Blend will work best.

Bob.
Lou van Wijhe wrote on 11/4/2008, 1:31 PM
Using the defaults (both BD and DVD) I get an output that is very contrasty, much of the shadow detail is lost. I've been fiddling with my Sony Bravia LCD TV because I thought it wasn't adjusted properly.

However, I just frameserved the same footage to TMPGEnc 4.0 XPress, encoded using its DVD template and it came out perfectly! It closely matches what I see on my LCD PC monitor.

Is this a peculiarity of the MainConcept encoder? I would like to continue using Vegas for encoding because of the smart rendering. Any ideas?

Lou
farss wrote on 11/4/2008, 1:40 PM
Are you using 32bit processing by any chance?

Bob.
Lou van Wijhe wrote on 11/4/2008, 1:46 PM
No, 8-bit.

Lou
farss wrote on 11/4/2008, 5:52 PM
Strange, I do a lot of 50hz HDV to 16:9 SD PAL DVDs and haven't noticed that at all although I'd rarely get to see it on a LCD TV, I just check it on a 16:9 CRT TV. LCDs do tend to crush the blacks but it can't be that if a different encoder produces results that you say look OK.
All I can suggest you try is bringing the results from both encoders back into Vegas and looking at them with the waveform monitor. They should look almost identical. To make the comparison easier you could try encoding a few seconds of the gradient test pattern.

Bob.
Lou van Wijhe wrote on 11/5/2008, 4:17 AM
Thanks for thinking along with me, Bob. I tried to import the TMPGEnc encoded files into Vegas to look at them with the waveform monitor but Vegas won't import them. DVDA does (without recompression) but not Vegas.

When I play both discs on the PC, the MainConcept one looks only a bit darker but this is much more pronounced on the LCD TV, the images look very hard. This may indeed be the LCD effect you mentioned.

I'll do some more testing and report back if I find something.

Thanks again,
Lou
fldave wrote on 11/5/2008, 4:42 AM
I'm finishing up a project and noticed my NTSC output looked dark upconverted by PS3 to 67" Samsung LCD-DLP, and 42" flat panel LCD. Tried a lot of Mainconcept settings.

Then I encoded with the TMPGenc trial via frameserver. Wow, huge difference, so I bought TMPGEnc.

Maybe it has something to do with the type of footage, ie. stage setting, dark background, dark hair, dark suit? TMPGenc handles shadows better? I'm very, very happy with the way it handles it, looks like it does on my calibrated CRT monitor, whereas Mainconcept didn't.
Lou van Wijhe wrote on 11/5/2008, 6:30 AM
I'm sort of glad that it isn't only me having this problem. However, have you been succesful in importing HD MPEG-2 files encoded with TMPGEnc into DVDA? With me only SD MPEG-2 files are accepted. When I import TMPGEnc HD files DVDA crashes.

Lou
fldave wrote on 11/5/2008, 7:03 AM
Haven't used DVDa for HD mpg yet, haven't upgraded this machine to DVDa 5.

No problems with SD. Looks marvelous.

Is the footage you are having trouble with darker scenes, or are you having trouble with outdoor/bright footage?
Lou van Wijhe wrote on 11/5/2008, 7:26 AM
HD Footage converted with Vegas' MainConcept encoder comes out too dark with much of the shadow detail lost. Frameserving the original footage to TMPGEnc results in excellent images, like you experienced, but only SD MPEG-2 files from TMPGEnc are accepted by DVDA 5, HD files not.

Googling the Internet I found out that this dark output from MainConcept is often reported.

Lou
Lou van Wijhe wrote on 11/7/2008, 2:59 AM
I submitted the following to the HV20/30 Forum (thread http://www.hv20.com/showthread.php?t=2251&page=7):

Some findings regarding Vegas:

1. Vegas uses the full 0-255 spectrum. Contrary to Lordtangent I did'nt see a cutoff at 16 using the Histogram function in Vegas.

2. The MainConcept plugin in Vegas doesn't translate 0-255 into 16-235 but processes it as if it were 16-235. This results in an image that looks contrasty and is darker than the original.

3. The quality of the MainConcept encoder is mediocre.

Testing methods:

Re 1.
Self-explanatory.

Re 2.
a) I have a MainConcept plugin from another editor (Editstudio 6 from Mediachance) where there is an option to choose if the source material is 16-235 or 0-255. The first choice results in the same murky image reported above, the second choice results in a correct rendering.

b) I imported an HD Test image (from http://www.belle-nuit.com/testchart.html) into Vegas and encoded it, once with Vegas Mainconcept's Blu-ray template and once by frameserving it to TMPGEnc 4.0 XPress. Using MainConcept everything under 16 and over 235 on the test chart disappeared, with TMPGEnc the whole range was preserved.

Re. 3
Test chart footage encoded via MainConcept quivered and shimmered, whereas the TMPGEnc footage stood as a rock.

Problem solved? Not yet: DVDA has difficulty importing TMPGEnc's MPEG-2 files. It either crashes or wants to recompress them.
I like Vegas as an editor and I do like DVDA. But the MainConcept plugin spoils the whole thing to a large extent.

Lou
Robert W wrote on 11/7/2008, 3:26 AM
Vegas displays on the timeline and the preview window in the 0-255 spectrum (computer colour) by default, but this is irrelevant. As far as I am aware, all MPEG 2 formats work in Studio RGB (16-235).

If you render Studio RGB footage as if it were Computer RGB, you are going to move the whitest point down to 235 and the darkest point up to 16. It will be less contrasty, but it will be incorrect. Glenn Chann's article explains this very well.
Lou van Wijhe wrote on 11/7/2008, 3:48 AM
Whatever the cause, using the MainConcept encoder produces a result that isn't a correct representation of the input.

Could you give me a link to Glenn Chann's article? Thanks!

Lou
farss wrote on 11/7/2008, 4:19 AM
"If you render Studio RGB footage as if it were Computer RGB, you are going to move the whitest point down to 235 and the darkest point up to 16."

That wouldn't be that easily achieved though.
If (in absolute values) your footage goes from 16 to 235 and you render it out your output will go from 16 to 235, Vegas will not shift levels. This is pretty easy to test. Render something out and compare the rendered output to the source using scopes.
Vegas is completely agnostic about the whole Computer / Studio RGB thing, at least in 8 bit.
Where it gets messy is some codecs such as WMV seem to expect values from 0 to 255. Vegas doesn't adjust the levels going into the encoder so the output can look washed out unless you shift the levels with say the Levels FX.

Bob.
Robert W wrote on 11/7/2008, 4:24 AM
Yes but they were talking about encoding to the third party frameserver, and that had an option to distinguish if the source material was Computer RGB or Studio RGB. If they were selecting the Computer RGB option it would produce the kind of effects they are describing.
Lou van Wijhe wrote on 11/7/2008, 4:58 AM
QUOTE
Yes but they were talking about encoding to the third party frameserver, and that had an option to distinguish if the source material was Computer RGB or Studio RGB. If they were selecting the Computer RGB option it would produce the kind of effects they are describing.
UNQUOTE

No, it was the other way around. If I specified the source to be 0-255 Computer RGB, the output was correct, otherwise it wasn't.

I've always understood that the encoder should only remap to 16-235 if the input is 0-255; if already 16-235 it needs to only pass it through.

Vegas transmits 0-255 RGB to its encoder but from my tests it appears that the encoder doesn't read anything under 16 and over 235 in the input at all.

Lou
fldave wrote on 11/7/2008, 5:03 AM
I'm feeding both Mainconcept and TMPGEnc 16-235. MC is dark and TMP is not.

I didn't have any issue with TMPGEnc file in DVDa, no recompress here.
Lou van Wijhe wrote on 11/7/2008, 5:09 AM
In my experience only SD MPEG-2 files from TMPGEnc are accepted by DVDA 5, HD files not. I'll do some more testing.

Lou
Robert W wrote on 11/7/2008, 5:16 AM
I don't think there are many shooting formats that work in 0-255. You need to have headroom for studio formats.
Lou van Wijhe wrote on 11/7/2008, 6:53 AM
AFAIK, the standard for HDV and DV is indeed 16-235 but this rule isn't really enforced with camcorders, especially on the super white side.

What it boils down to in my case is the fact that I don't get a correct output with the MainConcept plugin but I do with other encoders. It's a pity.

Lou
Robert W wrote on 11/7/2008, 10:55 AM
I thought your source was HDV?
Lou van Wijhe wrote on 11/7/2008, 11:51 AM
Yes, it is, with output to BD as well as DVD.

Lou