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Old March 18th, 2002, 09:10 AM   #1
vasekesav
 
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choosing a codec

Hi,

is there anybody who would help me to answer these questions?

1/ Which codec is the best for EDITINIG purposes?
2/ Which codec is the best for DISTRIBUTION on CD-ROMs?

Ive been working on a project which includes these need-to-be-done steps: 1/ conversion of the ripped *.vob files into avi (using FlasKMPEG) in order to get a source clip for later editing (in Premiere and AfterEffects); 2/ conversion of the edited material into the video format being used for distribution on CD-ROM.

I suppose that which is the best questions may sound a bit silly as the answer always depends on a number of circumstances which the author often forgets to mention. Not to do the same here are some of them:

1/ As for my computer: PC, Duron 750, HDD 30GB, 128MB RAM, 32MB video card. 2/ As for the speed-storage-quality problem: I really prefer to wait a bit (slow rendering) and delete something to make space for huge files than to edit clips of small, matchbox resolution. (Still eg there may be some too CPU intensive codec that would be annoying even for a patient man like me:)) 3/ As for the final product: Id like to make a multiplatform CD-ROM, for both PC and Mac comps, if possible.

As far as I know: 1/ for editing, codec using the frame-by-frame compression (may be Motion JPEG?), should be the best one. 2/ Im not sure but there may be some specific limitations (regarding a codec) when converting vob to avi. 3/ There must be some limitations regarding the editing software (I guess it does not support simply all existing codecs).

Thanks in advance for your help.

Vasek
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Old March 18th, 2002, 12:26 PM   #2
 
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your choices are Quicktime, SVCD(MPEG2) DiVX (MPEG4), and mini-DVD(MPEG2 DVD on CDROM). See TMPGENc and visit www.vcdhelper.com. SVCD and DiVX both work very well.
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Old March 18th, 2002, 12:59 PM   #3
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For editing it is usually the best to stay with the source
compression/format if possible (MPEG2 is a headache in
this situation. VOB files are MPEG2 system files with MPEG2
video streams and other stuff in them. They need to be
de-muxed first.). If you do need to convert for editing
choose as low a compression as possible, uncompressed
preferred (but this eats lots of disk space very very fast!).
There are special mpeg 1 & 2 editors available though. I
have never looked at any, so I can't help you with this.

As far as output to a CD-ROM goes: it depends on which
audience you want to reach. If it goes out to the Mac the
best thing probably would be QuickTime. If you go PC go
AVI (preferably with a default codec, or ship/link a codec
which you are using). It also depends on the length of
your project and the minimum CD-ROM player speed you
are targeting. This all has todo with:

1. compatibility with systems
2. datarate
3. quality
4. duration

etc. you get the point.

Usually careful considerations and trying are the best
way to go.

Good luck
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Old March 18th, 2002, 05:07 PM   #4
vasekesav
 
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Thanks a lot for your reply,

I thought that it is almost impossible to stay with MPEG2 as it funtions on the motion compression base. As I know for editing I can use only source files compressed frame by frame, so I would have to somehow convert my MPEG2 to "only I-frame mode".

The problem is that I dont know what de-muxing stands for. Does that mean something similar to that switching to "only I-frame mode"?

Ive also tried to convert VOB files to AVI without any compression, but the quality of AVI files was quite dissapointing. (Not to mention how big files they were.)

Thanx again.

Vasek
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Old March 18th, 2002, 06:56 PM   #5
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Converting files from VOB into uncompressed AVI should yield
**NO** quality loss whatsoever. Probably something else
went wrong there. De-muxing is the process of splitting out
a file with multiple data streams in it into seperate files. So
from a .VOB you can get a video file, one or more audio files
and perhaps subtitles for example. This is the material you
work with. De-muxing has nothing todo with the DATA (ie
the video/audio) itself. It only seperates them so that you can
handle them. Muxing is the reverse process in which you combine
multiple files into one.

Now there are editors out there (I don't know how good they
are!) who can do native MPEG2 editing. Including non I-frame
files. But this will probably not be speedy editing. The best is
to convert to another format I think. Try some different formats
to see what they do to quality and filesize. You might consider
DiVX, DV or uncompressed. Perhaps there are other codecs,
anyone else?
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Old March 18th, 2002, 08:14 PM   #6
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For web delivery I LOVE sorenson 3.
Best quality of ANY web/CD rom video I've seen.
Requires quicktime 5, but I put the installer right on the CD-ROM
for both mac and windows.

Sorenson 3 costs money, but is worth IMO.
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Old March 20th, 2002, 04:35 PM   #7
vasekesav
 
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"Converting files from VOB into uncompressed AVI should yield
**NO** quality loss whatsoever. Probably something else
went wrong there."

You were right, uncompressed AVI just SEEMED to be quality-degraded, but in fact there is not any quality loss... I just made a wrong test of that quality (played quite a big AVI file in Win Media Player).

So now I have a great media source file for my project, but its - not surprisingly - a great file in relation to its size as well. Therefore Im considering making an offline edit with compressed AVI first, producing an EDL and then making an online edit with uncompressed AVI... but as a novice to these postproduction issues Im not sure about real possibilities of putting this into life on my PC. (Such as what kind of info is stored in EDL, etc.)

Vasek
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Old March 20th, 2002, 04:51 PM   #8
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codecs

So...if you're editing uncompressed video (or "native"?)...you don't end up using a codec? It's only used for changing from one compression setting or type to another? is this correct?

(This is all so confusing sometimes) :)
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Old March 20th, 2002, 05:27 PM   #9
vasekesav
 
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Re: codecs

<<<-- So...if you're editing uncompressed video (or "native"?)...you don't end up using a codec? -->>>

Im not sure I got what you mean, but in case of editing uncompressed AVI (uncompressed RGB) you of course dont use any codec.

Vasek
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