Troublesome divx compression

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Troublesome divx compression

Postby rafi.ikari » Tue Oct 22, 2002 11:09 am

I have done a movie for school shot with dv camera, meaning that my video material is interlaced. Then my friends have made cg material to that video material. I'm supposed to compress this. I have cg progressive(p) and interlaced(i) video material mixed together, mostly video material. I know that you should avoid mixing progressive with interlaced material. But that will have to do for this time. I have tried different deinterlaced methods and are wondering which would be best to use for p and i material mixed together.

Blending:
When I blend the material everything looks good, except for some scenes. That is when two fields gets seperated by fast changing scenes. Then you see two distinct seperated fields blended together. Otherwise the video material looks really nice.

Discard field then resize
First I have to get understood what this means. When you discard the fields do you take away every other field? Doesn't this mean that you lose half of the vertical resolution? Does it show the same field twice (p) instead of two diffrent (i)? Beacuse it looks like it has dropped resolution in the cg material when I resize it back to 720x576 (pal). I see jagged corners in only the progressive material, which I do not like to see. Does this mean that I have lost resolution.

When I compress the video to a 720x576 divx file it is very heavy. The framerate stays around 22 frames/s when it should be 25 (pal). Is it because of the high resolution. Can you prevent this without losing resolution. It seems like the bitrate doesn't matter.I get the same results if I use more data/s.

What do you recommend me to do?

Ps. Do not say read ermacs guide. I have, believe me. Just don't fully understand the Fields vs. Frames part.
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Postby klinky » Tue Oct 22, 2002 11:19 am

Well since you have both progessive and interlaced footage then IVTC is not a option atleast now. I guess PAL is a bitch to IVTC properly anyways.
I think your best bet is to use the <a href="http://shelob.mordor.net/dgraft/smart.html">smart deinterlace filter</a> for virtualdub. It'll only de-interlace noticable lines.

If you're trying to keep the res @ PAL DVD res, I'd just max the bitrate out. If it's 3.11a, just slide it all they way over. If you want web distro I would reduce the resolution by half and use a 900kbps - 2000kbps bitrate. It'd be even better if you used a codec that allowed for two-pass. Such as XviD or nandub w/ 3.11a.

As for fields frames, just think of when you view the TV you're only viewing one set of the fields at a time(even or odd), but it does that 50(pal) times a second. On computers or progressive displays it shows both even and odd fields at the same time, but only @ 25(pal) times a second.


~klinky
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Postby Zarxrax » Tue Oct 22, 2002 2:40 pm

The fps it displays in vdub when encoding is the frames per second that it is encoding, not the speed that the file will play at. In other words, that is the SPEED at which it is encoding.
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Postby rafi.ikari » Tue Oct 22, 2002 2:47 pm

Zarxrax
The fps it displays in vdub when encoding is the frames per second that it is encoding, not the speed that the file will play at. In other words, that is the SPEED at which it is encoding.


I am a newbie, but I'm not stupid. =)
I really meant that the playback speed was 22 fps. My encoding speed is usually around 5 fps.

Ps. How the heck do get the username you want to quote after "quote:"?
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Postby klinky » Tue Oct 22, 2002 2:55 pm

You did export @ 25fps? What program did you use to export? This is a PC right? Those de-interlace tests you did earlier are from virtual dub? You didn't change anything under Video|Frame Rate?

Where does it report to you that it's playing back at only 22fps? What divx codec are you using?


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Postby rafi.ikari » Tue Oct 22, 2002 3:11 pm

Thanks klinky, REALLY!
I'm gonna check out that smart de-interlacer. It's just what I was looking for. I use nandub w/ 3.11a.

klinky wrote:If you're trying to keep the res @ PAL DVD res, I'd just max the bitrate out. If it's 3.11a, just slide it all they way over. If you want web distro I would reduce the resolution by half and use a 900kbps - 2000kbps bitrate. It'd be even better if you used a codec that allowed for two-pass. Such as XviD or nandub w/ 3.11a.


What should I slide? I only find slides with divx5. If the slide that all the way, I goes up to 10000kbps. Is that what I should use?
You say:It'd be even better if you used a codec that allowed for two-pass. Such as XviD or nandub w/ 3.11a.
I have never got the 2pass work with divx5, is it just me or doesn't it work?

klinky wrote:As for fields frames, just think of when you view the TV you're only viewing one set of the fields at a time(even or odd), but it does that 50(pal) times a second. On computers or progressive displays it shows both even and odd fields at the same time, but only @ 25(pal) times a second.


This I understand perfectly. I meant Ermacs de-interlacing recommendations, but nevermind that.

Ps. I understand now how the quoting function works. =)
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Postby rafi.ikari » Tue Oct 22, 2002 3:15 pm

klinky wrote:You did export @ 25fps? What program did you use to export? This is a PC right? Those de-interlace tests you did earlier are from virtual dub? You didn't change anything under Video|Frame Rate?

Where does it report to you that it's playing back at only 22fps? What divx codec are you using?


~klinky


I have a pc. I use nandub with 3.11a. I have not change my video frame settings. They are set to 25 fps. I measure the playback fps in a player called media player classic.
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Postby klinky » Tue Oct 22, 2002 3:18 pm

nandub was written to work with 3.11a specifically. It's actually quite different from the standard compression options window you would find in VirtualDub. I wouldn't mess with any codecs other then divx 3.11a in nandub, instead use VirtualDub for those. I am not a big fan of nandub either since I've used it maybe twice. I would just reccomend that you get Virtual Dub. Bring your file in, setup compression to 3.11a or DivX5 and if you want to keep it at the DVD res of 720x576 I would set the bitrate quite high. DivX 3.11a maxed out at 6000kbps(6mbits). So anything
around there should be fine.

If you want to do two pass, then I would use a codec that supports it internally like DivX5 or XviD rather then use teh evil nandub(okay it's not that evil, just complex).


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Postby rafi.ikari » Tue Oct 22, 2002 3:33 pm

klinky wrote:nandub was written to work with 3.11a specifically. It's actually quite different from the standard compression options window you would find in VirtualDub. I wouldn't mess with any codecs other then divx 3.11a in nandub, instead use VirtualDub for those. I am not a big fan of nandub either since I've used it maybe twice. I would just reccomend that you get Virtual Dub. Bring your file in, setup compression to 3.11a or DivX5 and if you want to keep it at the DVD res of 720x576 I would set the bitrate quite high. DivX 3.11a maxed out at 6000kbps(6mbits). So anything
around there should be fine.

If you want to do two pass, then I would use a codec that supports it internally like DivX5 or XviD rather then use teh evil nandub(okay it's not that evil, just complex).


~klinky


Problems. I have both virtualdub and nandub. I have both the divx3.11 and 5. I started with virtualdub and tried divx5's internal 2pass vbr, did not work. tried virtualdubs 2pass vbr with divx5, did not work. I got nandub with 3.11 and tested 2 pass, IT WORKED! Since then I have sticked to nandub and like it. And when i installed nandub it for some reason took away the 2 pass option from virtualdub. So now do not have a 2pass option in Virtualdub anymore. STRANGE =(
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Postby klinky » Tue Oct 22, 2002 3:44 pm

I wouldn't worry about two pass right now at the moment. Two-pass just makes the encoder use bits more efficently. This will really help once you get into lower bitrates. I would first focus on exporting a file that plays at proper speed. There really is no reason why it shouldn't.

I would just watch the video and see if it actually does look out of synch at all. Sometimes media player statistics can be off the mark.



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Postby rafi.ikari » Tue Oct 22, 2002 3:56 pm

I tested some settings. Used high bitrate, the files goes smooth now. That's very good. But I seem to prefer blending over interpolation. I really can't stand the jaggies.
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Postby klinky » Tue Oct 22, 2002 4:19 pm

Hows the smart deinterlacer doing ?


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Postby rafi.ikari » Tue Oct 22, 2002 4:50 pm

klinky wrote:Hows the smart deinterlacer doing ?


~klinky


Not so well. Haven't made anything good looking. Will try some more...
Another question:
When I use avisynth to take in a dv file to nandub the compressed file only gets black because of video desync something, how do I prevent this? Have not enough space to convert it to huffyuv.
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Postby Zarxrax » Tue Oct 22, 2002 4:51 pm

The frame rate display in media player classic is NOT an accurate display of the actual fps that the file is encoded at! To check the fps, you should right-click the file, go to properties, and then to summary.
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Postby rafi.ikari » Tue Oct 22, 2002 5:00 pm

Zarxrax wrote:The frame rate display in media player classic is NOT an accurate display of the actual fps that the file is encoded at! To check the fps, you should right-click the file, go to properties, and then to summary.


If you skip around in your video it's not. If you let it play from start it's pretty accurate I think. I look at the jitter too.
Does the summary page show the actual framerate, doesn't it show what I have specified the video framerate should be. My summary page shows 25 fps. I hope you are right. =)
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