Interlacing, CBR vs VBR and Avisync

[Cooper]

Hi!

I hope, this wasn't discussed before (at least not in the last weeks), so I dare to ask some things, that would let me look like a newbie to you, but I am not. Really! :D

First of all, i would like to ask, if constant bitrate does really provides a better quality on short movies. When I encode a movie under 40 minutes with maximum constant bitrate, is it better than a VBR 4 pass. In other words, does a multipass-process calculate the best usage of bitrate per frame or does it also calculate, which part of a specific frame got the most motion? Couldn't find an unambiguous answer elsewhere.

Then I experience a problem on encoding interlaced DVDs to SVCDs, because telecide works in (very few, yet some) scenes not perfect. And when encoding with "no deinterlacing" the picture and sound on my standalone wouldn't play properly. Found a hint in one threat, that maybe it works, if I don't deinterlace and switch off CCEs progressive frame option. Will test this.

But I was wondering also, if there is a way to see, if a vob-file is interlaced or not, before encoding. Is there a tool?

And the last (and biggest problem)...when encoding avis to svcd, dvd2svcd always worked fine. But since recently, I got some files, that won't work. Got 6 videos of a series and one through five works perfect, but the 6th file always produces (after the complete encoding/muxing process) an image with sound, but a black screen with the only the words "Avisynth: caught an access violation at 0x0e2dea78, attemping to read from 0x0f5ee000" in it. Choosing another file, DVD2SVCD works perfect again, back to this file, it doesn't. I checked the file in VirtualDub and no corruptions were found. Does anyone knows this problem? First accured 2 weeks after upgrading to Windows XP.

OK, that was quite a lot of questions, I hope you're not all laughing and pointing at me now ;-)

Thanx

[ux-3]

But I was wondering also, if there is a way to see, if a vob-file is interlaced or not, before encoding. Is there a tool?

Simply use the preview function and look for comb effects, _repeatedly_. If you find them in even one frame, then it is interlaced!

Regarding your question concerning interlaced movies: If you already found some comments on how to do it, what do you expect from this thread? It can only yield suggestions on how to do it. Why don't you try first what is suggested and come back with the results?

[hoozdapimp]

about cbr v vbr...if you can do cbr and get the average bitrate near the max bitrate spec for svcd then there is no reason to do vbr...however, if your average bitrate is somewhere around 2000 to fill a cd and you want to fit it on one cd, i would suggest doing vbr since you will get extra room by encoding scenes that don't need lots of kb to encode and using that extra room to encode scenes that actually do need the extra space.

Originally posted by Cooper

And the last (and biggest problem)...when encoding avis to svcd, dvd2svcd always worked fine. But since recently, I got some files, that won't work. Got 6 videos of a series and one through five works perfect, but the 6th file always produces (after the complete encoding/muxing process) an image with sound, but a black screen with the only the words "Avisynth: caught an access violation at 0x0e2dea78, attemping to read from 0x0f5ee000" in it. Choosing another file, DVD2SVCD works perfect again, back to this file, it doesn't. I checked the file in VirtualDub and no corruptions were found. Does anyone knows this problem? First accured 2 weeks after upgrading to Windows XP.

OK, that was quite a lot of questions, I hope you're not all laughing and pointing at me now ;-)

Thanx

this problem occurs when there are bad (unreadable) frames in your divx file...you need to delete all these bad frames with virtual dub...there is an option under video to search for unreadable frames and then it's possible to delete them...do a search in the virtual dub forum, im sure you'll find your answer...however i do know that this is your problem, im just not 100% sure on how to fix it :)

edit: i was unsucessful on searching myself, but i think you can do this. scan for video errors...go to edit, and delete selected frames...after this check to make sure your audio and video are still in sync :)

[markrb]

I cannot help with the other questions, but on VBR vs CBR:

In short CBR has two advantages.

1. It's quicker
2. It guarantee's consistent quality throughout.

CBR has disadvantages:

1. Wastes bits on scenes that don't need them.
2. Can force you to use a lower bitrate in complex scenes for the same amount of space as VBR.

VBR has the following advantages:

1. Space is better used.
2. Uses more bits in complex scenes where needed.

VBR has the following disadvantages:

1. Slow
2. Can make mistakes and not use enough bits in complex scenes. (The amount of errors decrease with each pass until around 4 where it no longer has much to do.)

In short there is no reason to use VBR if your Avg bitrate of a CBR encode will be around the same as your MAX bitrate of a VBR encode for the same number of cd's and video length. The more these start to seperate the more reason there is to use VBR.

Wow I think I did a good job on that explanation. I might just add it to the Q+A.

Mark

[chainsaw135]

lol@markrb yeah you do that:D

[R2D2]

@ markrb

Yeah, Mark, please Stick It! :) It will a great "clarifier" for newbies on how to decide to do their encodes.

@ Cooper

I don't pretend that my way of doing encodes is best, but I feel it will suit you. Since size it is not an issue for me, I do CBR @ 2490 Kb/sec bit rate, creating SVCD's of around 40 mins each - I select the necessary number of chapters to reach that duration. I agree that, sometimes, due to time constraints of the chapters (maybe 41 minutes for a disc), I had to decrease slightly the bitrate, but no less than 2350. Recently, I stopped making CD images, and cut the big MPEG-2 file as I wish with M2Edit-Pro.

The results have always been of great quality, and the spent time for the process is minimal.

[hoozdapimp]

hey mark, i think my explanation was just about perfect, but you clarified the points better than i did i guess :D

[Abond]

@hoozdapimp
...if you can do cbr and get the average bitrate...
@markrb
if your Avg bitrate of a CBR encode
Hmm... sounds funny, isn't it?:p

[Jezz]

Originally posted by Cooper
\]But I was wondering also, if there is a way to see, if a vob-file is interlaced or not, before encoding. Is there a tool?



Well if you have ripped the dvd to your hard drive you can open up DVD2AVI (you will find in your dvd2svcd dir) click on open find your vob files click the open button in the file dialog then click OK then push F5 for a preview you will get a window to the side that will tell you a whole heap of info Preff ESC to stop the preview

But this only works if you have pre ripped it as dvd2avi doesn't like encrypted vob files direct from the dvd

[markrb]

hoozdapimp your explanation was fine. I just wanted to show the positive and negatives behind each encoding method. Not so much to give advice on settings as you did. Since you did that already.


Mark