DebugMode frameserver output: RGB24, RGB32 or YUY2 ?

[codemaster]

DebugMode Frameserver has these 3 formats of video output, RGB24, RGB32 and YUY2. How do I know wich to select, or is it best to leave the default RGB24 ?

And should I check another option called "Write audio as PCM samples in signpost AVI" ?

I would like to know what these 4 options mean, so that I know wich one to use and when.

[poisondeathray]

RGB32 is RGB24 + alpha channel . So if you want to preserve alpha you should use it, otherwise use RGB24

YUY2 does a conversion to 4:2:2 , basically you should never use it, because vegas is operating in RGB most of the time (unless you have a cuts only project with DV, HDV or MPEG2) . Other programs give you better control over colorspace conversions anyway

The audio option passes audio through to the dummy AVI, check it if you have audio in your project

[codemaster]

but if my source is MPEG2 and NLE is Premiere Pro CS3, between RGB24 and YUY2, wich one is capable of outputing a signpost avi without any loss in quality ? Are both equally capable of preserving the quality ? Does this depend on the colorspace of the source mpeg2 that I'm editing in Premiere ?

[poisondeathray]

same. premiere mostly works in RGB (unless it's a dv-avi project without filters (cuts only editing))

you want to avoid colorspace conversions, each time you go back & forth you lose a bit of quality. So if premiere converts to RGB, stay in RGB as long as possible. Your final format goal will probably be YV12, not RGB, but don't convert to that until the very end

[codemaster]

I just saw on debugmode site, it says that premiere processes YUV clips in YUV color space wherever possible, wich means that premiere outputs in YUV to the frameserver and if I select RGB24 for the signpost avi, I think that it will convert YUV to RGB24. In the MediaInfo tab in MPC-HC it displays that the color space of my source .m2v is YUV

[poisondeathray]

debugmode site is wrong, or at the very least, it's incomplete

Only if you do cuts only editing, and only for DV-AVI. As soon as you apply any filter or transition, it gets converted to RGB internally. Premiere outputs RGB 99% of the time, the only exceptions are smart rendered projects (DV-AVI, HDV) , and only with cut type editing (no effects) , and if you choose to export a YUV format like MPEG2, MPEG4, etc... you have incurred some quality loss from RGB=>YUV conversion.

MPEG2 for DVD is YV12 (YUV colorspace, 4:2:0 sampling) , so eventually you have to convert to it if that's your final format goal. You have to incur that loss at some point. You cannot avoid the RGB conversion if you use premiere (unless it's DV-AVI smart rendered project).

It's not a huge loss (visually you won't tell difference, unless you pixel peep and zoom in), but the only way to avoid it is to stay in YUV space (i.e don't use premeire)

[codemaster]

Understood, thanks. One more question, related to what you said about how it is best to avoid this type of conversion:

in a professional studio, where they edit a documentary for example, are they avoiding RGB output somehow ? As part of their procedure or workflow ? Or the slight loss resulted from converting between color spaces is neglijable for them, in a way that it allows them to still achieve professional results ?

[poisondeathray]

in a professional studio, where they edit a documentary for example, are they avoiding RGB output somehow ? As part of their procedure or workflow ?

It depends how "high end"

For example, film scans for Hollywood productions are 16-bit RGB 4:4:4. They stay in RGB all the way through the workflow, editing, grading, final master, until the very end delivery format (e.g. DVD or blu-ray). Only the end delivery format is Y'CbCr (YUV) in 4:2:0, because of the lower bandwidth and bitrates. Delivery in RGB would be impossible with today's compression technology - the bandwidth would be too high

All software for grading & color correcting work primarily in RGB. (In some programs you can grade in HSL or CMYK, but it's been converted from RGB). Most editing software works in RGB as well (the exceptions are those formats that can smart render - but those aren't high end acquisition formats; really high end acquisition are usually RGB, or at least Y'CbCr 4:2:2)

Once you're in RGB, you should stay in RGB (avoid colorspace conversions). The final conversion step to Y'CbCr for end delivery format is unavoidable. The point is not to go back & forth a few times - that quality loss (however small) - is avoidable.

Professional studios don't start with a low quality DVD MPEG2 source. They start with something much better. For example , BBC doesn't even consider 4:2:0 subsampled content for submission, as "HD" for their programs or documentaries (even though chroma subsampling does not necessarily have anything to do with "high definition"... go figure). It doesn't meet their minimum standards

[rallymax]

would it help if I made a little plugin that simply pops up a dialog box and says what mode Premiere (or Encore or AE) is going to provide the output Encoder? You could then hit cancel and open up the encoder you actually intend to use and know what mode the sequence/timeline is going to come in as.