Video Color Depth question

[arnie.d]

Hi,

I'm really confused about the video color depth. I have a dv avi, I want to filter it a bit with avisynth using virtualdub, save it as a huffyuf avi and encode it with cce sp.

Now, when I open the .avs file in virtualdub and check the info it says the decompressor is YCbCR 4:2:2 (YUY2). Well fine by me, that's also the color depth of dvd right? But in virtualdub you can choose:
http://img135.imageshack.us/img135/3637/clipboard016ib.jpg
1) Does it make any difference for the output file/format what decompressor I choose?
2) When I choose 24 bit for "output format to compressor" and I encode the avi the colors are bad, it looks like I'm looking at an old EGA screen. When I choose 4:2:2 YCbCr (yuy2) I think it's OK. What should I choose?
3) Also, why does the video look so dark in virtualdub when previewing with 4:2:2 compressor/decompressor compared to 24 bit?

[zilog jones]

DV uses 4:1:1 for NTSC and 4:2:0 (YV12) for PAL, although different DV AVI codecs may output the video in different colourspaces. However, DVD video uses 4:2:0 (YV12), not YUY2. So if you're using PAL video, try and keep everything in YV12 - you shouldn't lose quality through colour conversions this way. I dunno what to do with NTSC DV - someone with more experience with it will probably be here soon ^_^

What MPEG-2 encoder are you using? IIRC certain encoders like certain colourspaces better than others for the input. YV12 is preferred for QuEnc (and probably other libavcodec-based encoders), and RGB24 is preferred for TMPGEnc - I can't remember what the others work with best.

[arnie.d]

Thanks for the reply.

My DV is PAL. Oops, that's right, DVD is 4:2:0. I use cinema craft encoder sp for encoding. So I should just use 4:2:0 planar YCbCr (YV12) for in and output in virtualdub and it'll be alright?

[zilog jones]

Hmm, it seems CCE prefers (or even requires) YUY2 input, though I've never used it myself. So you may need to convert it to YUY2.

Anyway, can CCE not encode straight from AviSynth filters?

[arnie.d]

Yes it can but the filters I use are very slow so the encode would take to long since I use 10 pass encode.

edit: cce doesn't take YV12, back to 4:2:2 YCbCr (YUY2) output I presume...

[tedkunich]

Yes it can but the filters I use are very slow so the encode would take to long since I use 10 pass encode.

...


10 Passes???? My god man, to what end??? you will not see any noticable difference going from 2 to 3 passes, let alone 10 passes - is just a waste of your time.

[arnie.d]

Yes you can see a difference. Especially when projecting with a beamer.

[foxyshadis]

When you save to huffyuv, depending on the codec, it may convert to yuy2 or yv12 anyway. Just add ConvertToYUY2 to the end of your scripts, and use mode "fast recompress" to encode to huffyuv, and you'll have no colorspace issues.

DVD actually benefits more from 3 passes than mpeg-4, I think because of the high bitrates. But more than 4 through CCE is universally derided, it simply does not have a perfect enough rate control. You shouldn't use more than 3 passes unless you actually know what multi-pass does (hint, it's not a higher-quality option) and must have it. Especially if you haven't turned every single other quality option to max.

[Mug Funky]

Yes you can see a difference. Especially when projecting with a beamer.

umm... how about doing 2-passes, then filling the bad parts with segment re-encodes at a higher bitrate. come on, nobody has THAT much time on their hands...

you'd be better off just encoding at a higher bitrate and using more discs (or switching to DL media). for CCE anything over avg 4000 kbps with a max around 8500-9000 will be fine even with 1 pass...

it's generally accepted that 2 passes should be all an encoder needs unless there's something really wrong. i suggest you do a blind test on said projector between a 2-pass and 10-pass encode (it's possible to author a DVD to play bits of video randomly... you could do that).

[edit] OT:

i think the CCE devs should limit the number of passes to 3 in their next release. i'm sure their tech support is getting sick of tracking down RC problems on the 10th pass...

[arnie.d]

@ foxyshadis
Thanks for the tip about fast recompress. I always avoided that option because I thought "fast recompress" would mean "loss of quality"

@ Mug Funky
I already tested 1,2 and 10 pass encoding. You really can see a difference, especially in noisy film. When using 1 or 2 pass the picture in moving parts will be much more blocky compared to 10 pass. Besides a 10 pass encode on a 1 hour movie only takes about 10-12 hours so I let my computer encode during the night or when I'm to work during the day.