Comments on Xvid encoding settings

[the_wildcard]

Hi there, I am trying to encode a 8 minute, TV clip captured though my DV camcorder. 720 x 480, interlaced, NTSC.

I used Adobe premiere to edit the clips and output to a huge avi file. I am using Virtualdub to encode with xvid. I am not using Gknot.

I used a combination of settings from Doom9's guide and that in Crusty's FAQ. I am using the Koepi's 05062004 1.01 build of xvid.

Full processing mode
2 passes
H.263
Global motion, interlaced encoding, q-pixel
motion precision search - 6 ultra high
trellis quanitizaion
1359 kbps encoding (it's an 8 minute clip, 128 audio, want file size around 85-90 megs)

All other settings, including iframes, overflow, curve compression and quantizer restrictions are same as those featured in doom 9's guide

http://www.doom9.org/xvid-vdub-final.htm

Resulting file was around 85 megs, but I noticed alot of "blockiness". Basically I noticed that were alot of transparent, vertical rectangular blocks in the video.

Any comments? I have tried encoding without "interlaced encoding", GMC and didn't notice any change in the quality.

I know xvid is capable of much more so I know I am doing something wrong.

[communist]

Did you deinterlace the clip and if not do you deinterlace during playback?

[EthanoliX]

Hi there

I guess 1400 kbps is insufficient for a TV-capture of full NTSC resolution.

Even for my denoised and resized (480*352) clips an avg. rate of at least 1000 kbps is minimum.

So i would recommend stronger denoising and/or higher bitrate.

[the_wildcard]

You used a virtualdub filter to denoise? Which filter? 2d cleaner? temporal cleaner?

AS for the deinterlacing, I tried one time by using a deinterlacer filter in virtualdub while encoding. And then another time I used Xvid's option for "interlace encode" for whenver the source is interlaced.

[bjorn toulouse]

You are basicaly using the camcorder to capture interlaced content from tv, try the filters in Virual Dub
This guide is helpfull http:www.doom9.org\capture\start
It has some good bits about using Virtual Dub to prosses the DV. I like Deinterlace MAP and smart de noise. Once you have the video looking the way you want it to in the right hand window then code it to Xvid.
The bigest problems I get is that most of the guides presume you have used DVD2AVI they are geared up for DVD ripping.

http://www.doom9.org/xvid-vdub-final.htm
"Start up VirtualDub, press Control-O to load the AVS file GKnot has created for you"
How did you do this when you started with a DV source? I haven't sussed that bit yet.

I'm doing somthing similar but I'm getting a bit lost in Xvid's 2 pass encoding.

[the_wildcard]

Haha yes, I understand the confusion because alot of these guides are geared towards copying content to DVD's and using other programs like Gknot. I am not using Gknot.

In the guide, when it says "Start up VirtualDub, press Control-O to load the AVS file GKnot has created for you " I am just opening the AVI file that I used Premiere to save. Basically I downloaded the clips from my DV camcorder with Adobe PRemire and saved them as UNCOMPRESSED, DV type 1 avi files. (not avs)

[communist]

Originally posted by the_wildcard
I downloaded the clips from my DV camcorder with Adobe PRemire and saved them as UNCOMPRESSED, DV type 1 avi files. (not avs)
But why would you do this? Keep it DV until you convert to anything - this not only results in smaller (temp.) files but also in better quality.
If you save as 'uncompressed RGB' the files get bigger + you introduce loss of information due to color conversion. When you feed that file to a codec it will do another color conversion (to the codec's specific color space) and you'll lose information again.

As for your 'deinterlacing':
If you intend to watch the clips on PC you should deinterlace during encoding (feeding a deinterlaced / progressive stream to the codec) or you should deinterlace during playback (with ffdshow for ex.).
If you want to do the latter one then you need to check 'Interlaced' option in XviD. XviD will then preserve the interlaced structure of your stream and not possibly discard it as unrequired details.

[the_wildcard]

Originally posted by communist
But why would you do this? Keep it DV until you convert to anything - this not only results in smaller (temp.) files but also in better quality.
If you save as 'uncompressed RGB' the files get bigger + you introduce loss of information due to color conversion. When you feed that file to a codec it will do another color conversion (to the codec's specific color space) and you'll lose information again.

Hmm, I might be confused here. I don't understand when you say keep it DV. Am I not doing that when I capture the video clips from my DV camcorder with Adobe Premiere and save them as avi files. It saves them as DV type 1 codec.

If that's not what I am supposed to do, what would you suggest?

Originally posted by communist As for your 'deinterlacing':
If you intend to watch the clips on PC you should deinterlace during encoding (feeding a deinterlaced / progressive stream to the codec) or you should deinterlace during playback (with ffdshow for ex.).
If you want to do the latter one then you need to check 'Interlaced' option in XviD. XviD will then preserve the interlaced structure of your stream and not possibly discard it as unrequired details.

Hmm, so if I click the 'interlaced' option in Xvid, it preserves the interlacing and not DEinterlace it? I thought it was the other way around?

[Teegedeck]

Right; it does preserve the interlacing.

This is possibly one of the most common misunderstandings about XviD. Please consult Crusty's FAQ before changing XviD's defaults. :b

The FAQ should also explain what the switch actually does.

[communist]

Originally posted by the_wildcard
Hmm, I might be confused here. I don't understand when you say keep it DV. Am I not doing that when I capture the video clips from my DV camcorder with Adobe Premiere and save them as avi files. It saves them as DV type 1 codec.

If that's not what I am supposed to do, what would you suggest?
If you capture your footage from your DV cam using 1394 (firewire / i link...) it should be DV (unless you tinkered with the files). It should take about 3,5 MB/s.

Originally posted by the_wildcard
Hmm, so if I click the 'interlaced' option in Xvid, it preserves the interlacing and not DEinterlace it? I thought it was the other way around?
No as said it preserves the interlacing lines as it could be 'distorted / or lost' because XviD would assume its a picture detail and not 2 different fields. By checking the Interlace setting you will tell XviD to treat the video as an interlaced and not progressive stream.
Keeping things interlaced has it pros and cons:
Pros:
You keep more information and have a better temporal resolution (looks more fluid). If watched on TV it'll look just fine
Cons:
If you want to watch it on PC you'll see interlacing and either have to deinterlace your footage during encoding or during decoding to get rid of these lines. Doing it during decoding will eat some CPU power.

Just see what works best for you and what you intend to do with your encodes (watch them on TV or PC?)

[the_wildcard]

Thanks for the detailed responses!

I probably would like to watch them on PC, so I guess I could deinterlace during decoding.

I noticed that with the above settings, when I use the DEBLOCKING setting during DEcoding, the helps a little bit. In addition, I notice that the video is sharper than using Divx to encode.

I am going to try to denoise in an attempt to reduce the color blocking that is still appearing.

[*.mp4 guy]

if you want to watch it on pc you should deinterlace BEFORE encoding as it will be more bitrate efficient and look nicer.