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| jcsston |
| Posted: Nov 11 2002, 11:36 PM |
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Matroska Dev
Group: Moderators
Posts: 553
Member No.: 652
Joined: 3-November 02
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If my video is already in YUV2 format does the Huffyuv compression lower the quality more?
I know that YUV2 itself loses some of the color information. But my ATI Aiw format choices in VirtualDub capture are only YUV2 or UYVY.
So if I use Huffyuv to compress my captures am I losing quality?
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Use the Matroska file format |
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| Spire |
| Posted: Nov 12 2002, 12:01 AM |
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If your hardware captures directly in YUY2 format (which it does), you can capture directly to Huffyuv with absolutely no loss.
If you already have an .AVI file stored in raw YUY2, you can losslessly compress it with Huffyuv by using the Fast recompress option in VirtualDub.
If you use Normal recompress or Full processing mode, VirtualDub will first convert the YUY2 data to its internal RGB format. Huffyuv will then convert this RGB data back to YUY2, provided that you've configured Huffyuv to convert RGB to YUY2. This YUY2 -> RGB -> YUY2 conversion is not 100% lossless due to small roundoff errors, but the amount of loss is so insignificant that you really shouldn't worry about it. After all, if you're going to be using any filters, you don't have a choice anyway, and you must pass through RGB.
In short: No, if you use Huffyuv to compress your captures, you are not losing quality. |
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| jcsston |
| Posted: Nov 12 2002, 12:33 AM |
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Matroska Dev
Group: Moderators
Posts: 553
Member No.: 652
Joined: 3-November 02
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thanks
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Use the Matroska file format |
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| fccHandler |
| Posted: Nov 12 2002, 07:57 AM |
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Administrator n00b
Group: Moderators
Posts: 3961
Member No.: 280
Joined: 13-September 02
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Excellent answer! (Spire knows his stuff) 
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May the FOURCC be with you... |
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| Spire |
| Posted: Nov 12 2002, 11:04 AM |
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I have just made a somewhat unsettling discovery regarding the level of lossiness associated with the YUY2 -> RGB -> YUY2 conversion process that I mentioned above. I am currently investigating the problem, and am in the process of running a battery of tests. I'll try to post the results within the next few days if time permits. |
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| greenval |
| Posted: Nov 12 2002, 12:30 PM |
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what about capturing with huffy codec? should this be an option?
In my list of codecs to use when capturing I only have DivX and uncompressed.??
Video card is nVidia GeForce2MX VIO, on winXP.
Thanks!! |
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| Morsa |
| Posted: Nov 12 2002, 02:36 PM |
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Moderator of the Vdub support board
Group: Moderators
Posts: 640
Member No.: 246
Joined: 9-September 02
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Sure!! |
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| greenval |
| Posted: Nov 13 2002, 12:04 AM |
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gee..thanks for your help Morsa...haha..
So...the fact that I only have DivX and uncompressed for available compression methods means what?? And what do I have to do be able to capture straight to Huffy?? |
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| fccHandler |
| Posted: Nov 13 2002, 03:28 AM |
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Administrator n00b
Group: Moderators
Posts: 3961
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To capture to Huffyuv, your capture device has be able to output one of these formats: RGB (24-bit), RGBA (32-bit), YUY2, UYVY, or VYUY. Even if your driver's dialog doesn't display them, you may be able to select one of these formats with VirtualDub's "Set custom format" dialog. (I remember being pleasantly surprised to discover that my old All-In-Wonder can do YUY2!)
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May the FOURCC be with you... |
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| BaronVlad |
| Posted: Nov 15 2002, 07:01 PM |
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Terrorhörnchen
Group: Moderators
Posts: 335
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and I think he should download the huffyuv codec:
http://math.berkeley.edu/~benrg/huffyuv.html
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Hochachtungsvoll
BaronVlad
Deutsch >> Capture FAQ - Capture Guide
Englisch >> Capture FAQ - Capture Guide |
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| fccHandler |
| Posted: Nov 15 2002, 07:16 PM |
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Administrator n00b
Group: Moderators
Posts: 3961
Member No.: 280
Joined: 13-September 02
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@BaronVlad: Doh! 
@Spire: Still awaiting the results of your battery of tests.
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May the FOURCC be with you... |
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| greenval |
| Posted: Nov 16 2002, 12:30 AM |
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thanks guys..I have already downloaded huffy codec..I know it is installed because I can see it it control panel->system->hardware->video codecs...
vdub is capturing in UYVY, with Microsoft WDM Capture Driver (Win32)... but the only codecs I can choose to capture with are divx and uncompressed.
I hope its not a XP problem?? |
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