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Old 4 Mar 2005, 12:54 PM   #1
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Default Bad Xvid Encodes

Hi all, i havent been to this site for a couple of months, but uni has started again, which means i'm back

I recently got a HDTV Capture card, which, btw, gives THE BEST quality video i have ever seen in my life

for some reason, however, one of my favourite shows, 'lost' always comes out in really bad quality when i encode to xvid. i will provide a link to a clip of the original mpeg-2 source soon, so you can try encoding for yourself and see if you can get a good looking xvid encode. for some reason it turns out looking really really bad, even on best post-processing with ffdshow.

the original is: 720x576, PAL 25fps, interlaced (NOT shown in HD on stupid Australian TV)

It happens on all my recordings of 'lost'.

Thanks!
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Last edited by anonymez; 4 Mar 2005 at 02:56 PM
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Old 4 Mar 2005, 01:18 PM   #2
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What software are you using to encode to xvid?
Why?
Can you not capture directly to avi/xvid? (hardware mpeg-2 card)
What is it you want for the end product?
Is this just for storage?
Further editing?
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Old 4 Mar 2005, 02:49 PM   #3
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sorry for the lack of detail (i was in a hurry). i think you may have misunderstood me. my hdtv card's only input are a standard tv antennae and s-video. the antennae captures resolutions ranging from minimum 720x576 to 1920x1440 hdtv maximum. there is no way any desktop pc could encode directly. since tv stations broadcast mpeg-2, there is minimal strain on cpu, depending on bitrate of video (can reach around 1.4 megabytes/second!)

1. i use dgindex, then the latest gordian knot to encode. bitrate 1000kb to 1100kb, resolution varies, but is usually at least 640 (its 16:9),

2.there are no hdtv hardware mpeg-2 cards that i know of. my tv card captures only to dvd compliant mpeg-2 (it would be waaaay too much strain on cpu to encode it directly)

3. i encode just for storage on hdd/cd

xvid settings are: mpeg quantizer, qpel, gmc, interlaced, b-frames, chroma optimizer, chroma motion, all search modes to max, keyframe interval 250

for some reason, the encode has way too many artifacts for the given bitrate and 'bits/pixel*frame". the final size (audio included) is 350mb. this has happened on every episode of 'lost', and have not seen such bad quality from a high quality source before

it has nothing to do with my post-processing settings. they are perfect.

Last edited by anonymez; 4 Mar 2005 at 02:55 PM
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Old 5 Mar 2005, 02:46 AM   #4
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1000kbps for Xvid isn't generally enough. I encode at 4000kbps, especially at that large aspect ratio.
If your card doesn't have a built-in mpeg-2 encoder, why are you only able to capture in mpeg-2? It's less strain to cap direct to avi, at a reduced resolution. Is this a software issue? Some software that you must have for THAT card? Is there nothing else you can use to capture (there's got to be a thousand different capping programs...)
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Old 5 Mar 2005, 07:16 AM   #5
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You might want to try good old Virtualdub to do your encode. I'm not putting any of the other programs down, which i've tried some, but I find myself relying on Vdub alot.
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Old 5 Mar 2005, 11:54 PM   #6
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the thing is, that i can encode a dvd movie to xvid at ~900kbps and it would look excellent. why should this mpeg-2 be any different?

unfortunately, most cards without 'BDA drivers' (a standard that allows cards to be compatible with many programs) can only function with its manufacturer's software and drivers. unfortunately, the program is the absolute worst program installed on my pc. i have to live with it.

this is definately not a software issue though. the mpeg-2 files are perfect quality in both audio and video, and are completely dvd compliant. it is just this particular show, 'lost' that i am having troubles with. i am not sure, but it may have something to do with not deinterlacing it. i will post a link to the clip soon i hope

i've attatched stills from both sources, zoom in and take a look at the difference. both dedcoded by ffdshow, no pp.
Attached Files
File Type: rar captures.rar‎ (298.5 KB, 86 views)

Last edited by anonymez; 5 Mar 2005 at 11:56 PM
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Old 6 Mar 2005, 07:05 AM   #7
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Hello Ziadost,

Some very useful software:

- HDTV MPEG2 to (Mpeg2 TS to Mpeg2 PS)
- DVD2AVI 1.77.3 (D2v project / Ac3 or Mpa)
- Virtualdub 1.5.10.1
- Avisynth 2.55 or superior

For IVCT, add some lines
Telecide ()
Decimate(cycle=5)

For the dÚsentrelacement:
FieldDesinterlace(threshold=15,dthreslod=9,full=Tr ue,blend=True,chroma=False)

Other:
SelectEven ()
Crop(x,x,x,x)
LanczosResize (X,Y)


Some ideal crop:

- ratio picture 1:85 in 1080i / Resolution in 1280p
crop(0,24,0-24)
LanczosResize(1280,688)

- format of origin of 2.35 in 1080i / resolution en1280p
Crop(0,132,0,-132)
LanczosResize(1280,544)

- format of origin of 1.85 in 720pi / resolution en960p
Crop(0,16,0,-16)
LanczosResize(960,520)

- format of origin of 2.35 in 720pi / resolution en960p
Crop(0,88,0,-88)
LanczosResize(960,408)


Note: it's only a method among so much other
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Old 6 Mar 2005, 09:17 AM   #8
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Quote:
i can encode a dvd movie to xvid at ~900kbps and it would look excellent. why should this mpeg-2 be any different
Because a DVD contains far more bitrate than your captured mpeg-2, and is much higher quality to begin with.
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