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Old 17th December 2008, 17:35   #21  |  Link
squid_80
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No, YV12 sucks compared to RGB or YUY2 because it has vertical chroma subsampling which might end up blending the fields. YUY2 would preserve the interlacing and it's closer to the original analog signal than RGB.
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Old 18th December 2008, 00:28   #22  |  Link
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Doesn't interlacing encoding completely separates the fields and encode them into different (virtual) frames ?
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Old 18th December 2008, 00:50   #23  |  Link
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The problem with some YUV formats is the chroma subsampling. The subsampling happens when converting from RGB to the YUV format, so before the actual encoding.
Subsampling may blend the (color) information of neighboring lines together, lines that belong to different fields and hence shouldn't be mixed together!

See this for more info:
http://en.wikipedia.org/wiki/Chroma_...ems_and_ratios

(I think 4:1:1, 4:2:2 or 4:4:4 would be okay for interlaced, but 4:2:0 wouldn't. Guess that's the YV12 -vs- YUY2 difference mentioned by squid_80)
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Last edited by LoRd_MuldeR; 18th December 2008 at 01:50.
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Old 18th December 2008, 10:42   #24  |  Link
2Bdecided
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YV12 interlaced still keeps the lines from separate fields separate - the "bluring" is within field, not across two fields. That's why YV12 interlaced sampling is defined as subtly different from YV12 progressive sampling.

If it wasn't so, then any movement on a standard interlaced source (never mind this 3D one) would have horrible chroma ghost trails. You sometimes see this when people handle YV12 incorrectly.


All that said, I wouldn't used YV12 in this instance.

Cheers,
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Old 18th December 2008, 10:57   #25  |  Link
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The "Assume interlaced if height >" option on ffdshow's input page would probably enable a proper interlaced conversion but I'm not sure.
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Old 18th December 2008, 16:38   #26  |  Link
BlackSharkfr
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ok i've done some new trys and it works much better.
This time i followed your recommandations
virtualdub capture + huffyuv and it is much much faster and allows me to play newer games and capture in real time.

I also found a way to display the "broken" image by forcing virtualbud to use a wrong input colourspace and then the preview just looked like the broken image i used to have.

I also noticed that with newer versions of ffdshow the broken image doesn't happen anymore with both Virtualdub and Dscaler, so i suppose it was a colourspace detection issue with older versions of ffdshow i used to have last time i tried to use ffdshow encoder in Dscaler.
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Old 19th December 2008, 16:06   #27  |  Link
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Quote:
Originally Posted by 2Bdecided View Post
YV12 interlaced still keeps the lines from separate fields separate - the "bluring" is within field, not across two fields. That's why YV12 interlaced sampling is defined as subtly different from YV12 progressive sampling.

If it wasn't so, then any movement on a standard interlaced source (never mind this 3D one) would have horrible chroma ghost trails. You sometimes see this when people handle YV12 incorrectly.
Well, it seems there is a way to convert interlaced material to YV12 properly. But that isn't automatic! It requires a "special" method.

From Wiki:
Quote:
With interlaced material, 4:2:0 chroma subsampling can result in motion artifacts if it is implemented the same way as for progressive material. The luma samples are derived from separate time intervals while the chroma samples would be derived from both time intervals. It is this difference that can result in motion artifacts. The MPEG-2 standard allows for an alternate interlaced sampling scheme where 4:2:0 is applied to each field (not both fields at once). This solves the problem of motion artifacts, reduces the vertical chroma resolution by half, and can introduce comb-like artifacts in the image.
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Old 19th December 2008, 16:38   #28  |  Link
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Quote:
Originally Posted by LoRd_MuldeR View Post
Well, it seems there is a way to convert interlaced material to YV12 properly. But that isn't automatic! It requires a "special" method.
That's what I've been trying to say With VFW there's no method to indicate interlaced YV12.
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Old 19th December 2008, 18:50   #29  |  Link
2Bdecided
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Well, conversely, there's no way to indicate progressive YV12 either! I'm not sure pixel aspect ratio gets communicated either. Neither does whether the actual content is progressive or interlaced. These are things you just have to "know".


It's not that it's "special" - it's just that you have to know what you're doing.

(I'm not saying it should be used in this context - just that interlaced YV12 is no more or less standard than progressive YV12 - or even interlacing itself!)

Cheers,
David.
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Old 20th December 2008, 23:07   #30  |  Link
LoRd_MuldeR
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Back to topic:

I have not tested it yet, but this looks like another options and an alternative to HuffYUV:
http://forum.doom9.org/showthread.php?t=143624
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