First pass no second!?

[birdy]

I have few questions about the first pass file avi and the stats file from 1st pass.

On few movies, I realized that my first pass avi file was even smaler then my desired final file. For example I wanted to make a 600MB file from a source avi that was 1.2 GB. But after doing the first pass I saw that the first pass.avi was only 490MB. I did a second pass setting the desired filesize to 600MB so that less compression would be used on the file and get 600MB final size.
But the secondpass.avi was even 3MB smaller and came out as 487MB!

My questions are:

1-Is there anyway to make the second pass file become at desired file size if the first pass is samller then that value?

2-If firstpass.avi file is about the desired final size, then should we use that file as final avi file or is there any advantage to go for a second pass?


These are the settings I used for my first pass btw:
Motion search : 6
H263
FourCC:Xvid
VHQ mode:1
B-frames:2,150,100
Chroma Motion enabled.
Other settings are all default.

btw My last first pass is 5MB biger then desired! Damn doing a second pass just for 5 MB Grrr :) Wish there was a faster way for such case!

[Koepi]

Take a look at the top of this page.

Yes, right. The SEARCH button.

Use it. Finally, get known to it. This isn't the first incident where you pick up a commonly known thing and are not capable of reading the FAQ or use the search (reading the documentation would help it as well).

Koepi

[birdy]

Did you read my question!? Or simply because I talked about undersize issu, you are telling me to read the faq and use search!?

There is nothing about this issu in the faq and I posted after using search and searching and reading for some time!

Most threads (the most useful ones) were not in this forum but in Divx forum and non of them answered my question!
I ALREADY know that using b-frames, resolution chioce, slow motion, and dark movies result in undersized movies.

My question is about 1st pass file, and I ask, if the first pass file is almost done at the size you desire for final size, should it be kept and consider that you done a good encoding or should one for example remove b-frame option, or set resolution to higher and redo a 1st pass to make a Big first pass and then make the size smaller in 2nd pass?

I am really sorry, maybe it's my fault, but I could not find answer to MY question when did a search!

[philippas]

1.You can use a sharper resize filter if you haven't done it already or increase the resolution. Also you can use a smaller interval for keyframes maybe 25 (1 keyframe/sec) and maybe tweak a bit the quant matrix to quantize less each frame.
I think if you search you can find alot of threads taking about that.

2.No it's not recomended because the limit for the max bitrate is to high for the first pass thus slow pc's might have problems decoding the clip. Other than that you can keep the clip.
A better way is to do a compresibility test and then if you can do a 1-pass quantizer with 2-2 quant.

[Acaila]

A better way is to do a compresibility test and then if you can do a 1-pass quantizer with 2-2 quant.XviD's 1st pass is exactly that. It encodes at the highest quality possible, so if that is already less than the size you want, you might as well keep it.

@birdy: You were searching for your specfic case, but the thing is your case is exactly an undersized issue problem. That is why Koepi told you to search. You just didn't recognize it as such.

[yaz]

@acaila
compessibility check is always done on a part of the movie. anyway, u're right. the technique is the same as for any 1st pass.

@birdy
search for compressibility issues. u got a very compressible source (guess an anime or so:-) try:
- bigger frame size
- extra sharpen
- lesser smoothing
- mpeg quant instead of h263
- ...

anyway, why do u bother with 1stpass.avi ? the info u need for 2ndpass is in the stat file.

the bests
y

[kilg0r3]

still, imo, it would be nice to get quant 1 to kick in here.

[birdy]

Originally posted by Acaila
@birdy: You were searching for your specfic case.

This is right Acaila. Infact I come to realize even more that the case is Very Specific one! And maybe worth to share my experience with others.

I thought that an already compressed file would be much harder to compress more! (example: zip an already ziped file or a rar file and you will see that it will not compress much more or most of the time not at all) BUT, I was somehow wrong! With video compression, it seems that an already compressed file, compresses even better then a non compresses one!

Maybe those who capture from TV should test this and see for themselves the fantastic result, that can be achived.

I capture my movies from digital reciever to XVID and then I resize it using Gknot and do a 1 CD file. The last cd I did was a movie of 2hours and 5 minuts long and it came out at 480MB. The quality is simply great! But what I see is that I almost never need to go for a second pass as the first pass is already the desierd size or even less!

Ofcours for resizing I use GKnot and use the explained resizing etc as told in guides to achive the right filesize. But apparently this calculations don't work for an already compressed files like mine!

If Gknot tells you that you should resize to for example: 576X208 to get the right filesize and compression then I can (should) go for :
672X256 to get the best out of my file!

I tried many times capturing to Mjpeg and then converting to xvid (this is the right and recommended way) But beleive me or not, capturing to XVID and then re-encoding to xvid gives so nice result that I could hardly make any differents, anyway not enough to be worth, as my goal it to make 1cd files.

I could upload some little examples if I knew an ftp just that you guys could see the results and tell me what you think!

[philippas]

I tried many times capturing to Mjpeg and then converting to xvid (this is the right and recommended way) But beleive me or not, capturing to XVID and then re-encoding to xvid gives so nice result

Well i do that also, i capture with 1pass quant 2-2 with xvid and the result is better than mjpeg, because with mjpeg u get very easy pixelation and the compression ratio is not as good as xvid which doesn't introduce pixelation in the frames.
Anyway if someone needs perfection they should use hufyuv or another lossless codec.


Ofcours for resizing I use GKnot and use the explained resizing etc as told in guides to achive the right filesize. But apparently this calculations don't work for an already compressed files like mine!

Just try to hit the 100% quality indicator, not 75% which is mentioned in the guides, by doing the things that were mentioned for undersized files in the previous posts.

[mf]

Try CBR @ 769kbit :D. That shouldn't undersize, and if it does, limit those quantizers :p.

[gldblade]

If it's undersized, turn off B-frames.

[ookzDVD]

Yes, for well compressed movie, which the 1st pass size is smaller
than the target size, better disable the b-frame.
and if still under size the target size, make the resolution larger,
if still undersize, use the .ac3 for the audio, if still undersize
better convert the .ac3 to .dts, if still undersize, better let it be. :)

[APF_Gandalf]

there is a way to force a size if Xvid undersized your movie for the first pass (even if it's undersized without B-frames and ax higher resolution).
I used it one time or two, seems to work well:
1) make your 2 pass first pass (oops, Xvid gave you a 500 MB first pass size).
2) load the stats files in stats reader and make a new stats file like always, BUT enter a size about 5% over your desired final file size (let's say 630 MB for 600MB aimed).
3) load the new stats file in stats reader (the one aiming at 630 MB) and make a second new stats file aiming at your desired size (600 MB in my case).
4) in Xvid, load the stats file aiming at 630 MB as if it was the first pass stats file (replace the one aiming at 500 MB) and the one aiming at the desired size (600 MB) as the statsreader's one.
5) encode.
6) enjoy your encoded movie that perfectly fits on your CD.