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| why is deinterlacing faster when using tv? http://forums.linhes.org/viewtopic.php?f=17&t=14813 |
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| Author: | imstr8trippin [ Tue Apr 03, 2007 1:46 pm ] |
| Post subject: | why is deinterlacing faster when using tv? |
does it make sense that my video will almost appear as its a little slowed down when watching live tv running interlaced? like the frame rate is just slightly too slow. it's not a horrible stutter. in fact, it is only really noticable when watching sports. i am able to run xvid/divx video perfectly fine. i am using my tv out on composite. i have recording res set to 720x480. i would think that running deinterlaced would be slower? i hate running xvmc and bob. while it does speed up the display, i hate the b&w/flickery osd. and, some channels just don't look good with them on (i.e. faint diagonal bars running across screen). can anyone explain/help??? check sig for hardware specs...any other info needed and i will be happy to provide! |
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| Author: | snaproll [ Tue Apr 03, 2007 1:49 pm ] |
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I'd try bumping memory up to 512k |
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| Author: | imstr8trippin [ Tue Apr 03, 2007 2:59 pm ] |
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why would tv be more memory intestive than watching a 700MB xvid file? is it because its recording at the same time???? also, that doesn't explain why running non-interlaced is slower than interlaced. the computer has to run an algorithm to remove the interlacing. wouldn't that consume more resources??? i dont't get it. 
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| Author: | imstr8trippin [ Tue Apr 03, 2007 4:18 pm ] |
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i think that raising my video bitrate for the default recording profile has improved the frame rate. i have 4800 and 7000 max. before, it was 4400 and 6000 max. |
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| Author: | imstr8trippin [ Tue Apr 03, 2007 6:05 pm ] |
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actually, i dont think that it made that much of a difference at all. i cranked it up and it looked the same. then, i put it back to 4400 and its still the same.
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| Author: | marc.aronson [ Tue Apr 03, 2007 7:14 pm ] |
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imstr8trippin, what type of display device are you using? If it's an hDTV, what is the native resolution of that device? Marc |
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| Author: | imstr8trippin [ Tue Apr 03, 2007 7:57 pm ] |
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its a 32 " TV. Only supports 480i. I seem to have gotten it to display much better now. I don't really know what change made things better. The frame rate seems better, but there is some occasional tearing. Anyway, this is what I have in some relavent configs... nvidia-settings: 0/SyncToVBlank=1 0/TVOverScan[TV-0]=11 0/TVFlickerFilter[TV-0]=50 0/XVideoTextureSyncToVBlank=0 0/XVideoBlitterSyncToVBlank=0 Recording profile: res: 640x480 bitrate: 4400 max bitrate: 8000 TV Settings->Playback: Deinterlacing: off MPEG2 decoder: Standard Enable OpenGL vsync: off Enable Realtime priority threads: off Use video as timebase: off Extra audio buffering: on Aspect Override: Fill Here is some relavent stuff in xorg.conf: Section "Monitor" Option "TVStandard" "NTSC-M" Option "ConnectedMonitor" "TV" Option "TVOutFormat" "COMPOSITE" Option "NoLogo" "1" # Option "TVOverScan" "0.6" Identifier "Monitor0" Option "DPMS" "true" Option "UseEdidDpi" "FALSE" Option "DPI" "100 x 100" HorizSync 30.0 - 50.0 # Warning: This may fry old Monitors VertRefresh 60.0 # Very conservative. May flicker. Section "Device" Option "UseEvents" "True" Option "RenderAccel" "1" Option "NvAGP" "2" Option "XvmcUsesTextures" "False" Res is 640x480 |
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| Author: | alien [ Thu Apr 05, 2007 2:52 am ] |
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If the problem is visible only when watching fast movement (sports), maybe these are interlacing artifacts that you are seeing. It is very difficult (possibly impossible) to take interlaced input and get it out a video card to an interlaced TV and have the original interlacing line up on the TV. A PVR-350 might do it, but otherwise, you need to deinterlace to get rid of the affects. I use kernel deinterlacing because bob has problems with the overscan options I'm using. Try out the various options. You do not need to enable XvMC to deinterlace (in fact, I think many of the deinterlacers are incompatible with XvMC). Enabling XvMC is what impacts the OSD, so by leaving it off you can keep the transparent OSD when using deinterlacing. Your HW should be able to handle SD without using XvMC. |
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| Author: | marc.aronson [ Thu Apr 05, 2007 8:15 am ] |
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In NTSC land you will find (at least) two distinct types of transmissions: 1. Interlaced: Typically used for live events, sporting events, news, talk shows and, strangely enough, reruns of "The Nanny". This type of transmission can be deinterlaced nicely using kerndeint. 2. Telecined: Typically used for shows originally recorded with film. Examples of telecined shows includes the various Star trek shows, smallville, JAG, the various Law & Order shows, etc. "kerndeint" will not handle these shows well. You need to use "bob2x". Some more factoids: 1. Bob2x will do a nice job of deinterlacing either type of transmission -- interlaced or telecined. That is why it is a popular method. 2. If you use XVMC, bob2x is the only deinterlacing process that actually does anything. The rest have no effect when XVMC is used. 3 If you are not using XVMC, bob2x will work fine but requires quite a bit more processing power than "kerndeint" as it doubles the data rate. 4. If you use "kerndeint" on a telecined show you will see what appears to be an occasional "glitch" or "stutter" in scenes with a lot of panning. That is because "kerndeint" assumes the stream is fully interlaced, and telecined shows do not follow the field pattern that "kerndeint" expects. Hope this info is useful... Marc |
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| Author: | tjc [ Thu Apr 05, 2007 5:22 pm ] |
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marc.aronson wrote: Hope this info is useful...
I'd list it as the most informative and useful thing I've read yet today! 
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| Author: | marc.aronson [ Thu Apr 05, 2007 7:54 pm ] |
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Glad you liked it. As I started playing with transcoding recordings to xvid I did a lot of research. Winds up the hardest issue to deal with is proper deinterlacing. The following article explains it well: http://www.mplayerhq.hu/DOCS/HTML/en/me ... cine-ident One of the things I've learned from all my research is that it's not the case the progressive scan is better than interlaced, or visa-versa. Assuming you use the same frame rate, there are scenarios where interlaced yields a better result and scenarios where progressive scan yields a better result. Marc |
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