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-   -   Mencoder: Predicted and bitrate (http://www.digitalfaq.com/archives/encode/9896-mencoder-predicted-bitrate.html)

maurus 05-26-2004 05:58 PM

Predicted and bitrate
 
Two questions:

1) Sometimes, the video file created with Mencoder is more short than predicted. With the same bitrate for 1 CD 89 min:

- With QuEnc=722 MB OK
- With Mencoder (with the temp.conf of MencodeMe, template DVD): 600 MB :?:

It is posible?
I have too many buffer underflow errors. It is the cause of the minor size? It lost frames?

2) Bitrate. I use overscan factor=2, check 16:9 source to LetterBoxed 4:3 and use those settings of new MenCalc for my settings in the file .conf of MEncoder. The crop is 448x432 and then expand with black to standard 480x576.

I must change to up the bitrate? I see how certain files are also more short of the predicted size. It is also the cause of the minor size?

Do you understand me? My english is so poor...

Thanks

-Maurus
p.d.
I changed keyint=15 for PAL (GOP size)

incredible 05-27-2004 03:52 AM

I assume the template u used got a lmin value of 1 (lmin=1) ... so do another test using lmin=0.5 and try again. BUT Phil reported some days ago that lower lmin values at 1cd encodings (= low avg bitrate) do mess bitrate curves up. I dont remember if that only happened at 1pass VBR encodings.

So do a test and lower the lmin value as desribed above and do a 2pass encoding (generally recommended when using mencoder).

That was exactly the reason why I made packshot purposed only for dvd encodings (=higher avg bitrate), as no matter which parameters are used:
WE STILL didnt found the "general" full k(S)VCD compilant parameters where all these issues do not appear in general:
a) No buffer underruns
b) constant quality in the whole stream
c) no max bitrate overruns (max 2500)

I did read in here so many issues related to 1cd encodings using mencoder that in the "parameter experiences"-state now ... I do not recommend using mencoder at 1cd encodings. But that could change very fast as its a matter of figuring out the perfect paramaters for that format. ;-)

maurus 05-28-2004 03:00 AM

Very important lmin=0.5.

The size now is correct, it is the same of the file created with QuEnc.

Thanks.

-Maurus


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