Re: [dvd::rip] consider frame range

Jörn Reder wrote:

> > Another point about size calculation: I figured out, that if I want a
> > file to fit on a common 700MB CDR, I have to choose exactly 735MB, which
> > results mostly in a 699MB file.
> 
> Hmm, these numbers look like a "kilo 1024 vs. 1000" problem, although 
> all bitrate calculation algorithms are absoutely aware of this. So I 
> tend to say "I don't believe you" ;) resp. "This depends on the material
> and is a result of the usual size divergencies for dynamic bitrate 
> encodings". But I'm not that arrogant, instead I'll check this twice, 
> before I give a final answer ;)

Ok, I just did this check: I transcoded a PAL 16:9 movie to 512x272 avi,
target size 700 MB with a calculated video bitrate of 901 kbit/s, using
xvid and mp3 audio, 128 kbit/s. The resulting file size was 731869026 
bytes = 697 MB, which is Ok (2 MB difference are normal). Then I did the
same transcoding with ffmpeg/mpeg4: nearly exactly the same file size, a
difference of just 85KB! As well I reviewed the bitrate calculation 
sheet and couldn't find any error (which was of course expected, because
dvd::rip's bitrate calculation algorithm didn't change for ages and 
works quite well for many people... ;)

So I think the differences you see are due to the dynamic nature of 
modern mpeg4 video codecs and probably depend on the input material, but
for sure there is no error in dvd::rip's video bitrate calculation.

Regards,

Joern

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