Premiere exports AVI fine, but TMPgenc makes m2v too dark???

[trimipi2]

Hey. I have been trying to encode an avi exported from Premiere 6.0 using TMPGenc. The AVI looks good, but when the resulting m2v file is too dark. I don't want TMGenc to change the contrast or brightness.

Any ideas?

[adam]

Read my posts here. https://www.videohelp.com/forum/viewtopic.php?t=174444&highlight=short

Your avi is apparantly in the 16-235 colorspace, and by default TMPGenc compresses the luminence ranges. So you are basically overcompressing your luma, resulting in overly dark picture. This is a common problem. You can solve this problem, at least with this particular source, by enabling the "Output YUV data as Basic YCbCr not CCIR601" option on the Quantize Matrix tab.

[trimipi2]

Adam. Thank you for the quick reply. Oddly enough, I already have that setting enabled. Moreover, I am using an analog source, and not DV. Is it possible that this setting should be disabled for my source?

[adam]

Well DV is just one example of a source which always originates as 16-235. If you read all of that thread you will see that most sources are actually this way too, and a captured source will always be like this.

You didn't mention how you were capturing. Does your software allow you to adjust what the color space is? You want to capture as 16-235, or it may be listed as CIIR601. Then you want to enable the "Output YUV data as Basic YCbCr not CCIR601" option in TMPGenc.

Since you have already tried using this option, maybe it will work better if you disable it. Its possible that somewhere in your process your avi is being stretched out to 0-255. But since the entire picture is too dark, and not just certain parts, it really sounds like you have over compressed your luminence values.

[trimipi2]

I read all of your very informative thread. I am capturing using Virtual VCR. I select YUY2 and Huffy. (IS YUY2 related to luminance?)

I then bring htis into Premier 6.0 for editing, and export as an AVI. I have read that some Main Concept's codecs can make the "Output YUV data as Basic YCbCr not CCIR601" setting counterintuitive. I don't know if Adobe uses Main Concept's technology to export my files, although I know newer versions of Premiere use Main Concept's mpeg encoding engine.

Perhaps I'll try disabling the "Output YUV data as Basic YCbCr not CCIR601" setting, and see what happens from there.

Thanks again for all your help!

[adam]

Yes YUV data does affect luminence simply because it only supports the 16-235 colorspace. You source is CCIR601, there is no doubt about that.

If you are saving in an intermediate codec then there is no telling what it is doing to your luminence values, well not with some investigation. That's the problem with using intermediate steps in between before encoding. You have to know how your luminence ranges are affected so you know how to handle them in the final encode. Anyway, yeah just try disabling that option and hopefully it will look right and in the future, you know to use this setting with this particular combination of software.

[trimipi2]

Thanks. One last thing. I never noticed this being a problem before I introduced Premier into the mix. Maybe I have to change the settings in Premier.

Another option I considered is frameserving the Premiere output without compression, to cut out the middleman. Do you think this would be a good idea?

And should I use something other than YUY2? My purpose is to put my video on DVD for tv viewing only.

[adam]

Yes, if possible frameserve. Its a pain because it goes sooo slow with Premiere but its probably still faster than outputting to an avi file, and it will probably solve your problem. If your intermediate codec is compressing your luminence ranges, on top of the fact that they are already as compressed as they are supposed to be (obviously if you got this off the tv they have already been compressed to CCIR601) then your setting in TMPGenc isn't going to matter. Even if you enable the "Output YUV data as Basic YCbCr not CCIR601" option and preserve the lumince ranges, its too late the damage has already been done. You did say that the intermediate avi file looked ok so I guess this didn't happen, but anyway, its always best to frameserve from the encoder if possible.

Honestly, if you are using TMPGEnc as your encoder than it really doesn't matter if you capture to YUV or RGB, or if you convert to RGB at any stage before encoding. TMPGenc only supports RGB input, so if its YUV its going to get converted to RGB anyway. If you were using something like CCE (cinema craft encoder) which supports YUV input directly, then you could save alot of encoding time and some quality by keeping it YUV through the entire process.

[trimipi2]

Very interesting. Yes, the AVI file Premiere created looked great.

I could easily use RGB to capture. I've always used YUV2, simply because that's what everyone always seems to recommend.

[dwiesel]

Adam…in terms of quality, do you recommend capturing to RGB24 (with the YUV to RGB24 conversion happening at capture time), or capturing to YUV and let TMPGenc do the YUV to RGB conversion? Thanks.