Hi!
> From: Bernhard Derks <[EMAIL PROTECTED]>
> Subject: [Mjpeg-users] Calculated bitrate, but file too large...and works slow
>
> ...
> So there are 1 files with ~17 GB in the working dir.
>
> I tried to encode with
>
> lav2yuv $1|yuvscaler -O SVCD|mpeg2enc -f 4 -q 7 -4 1 -2 1 -B 260 -b 1800 -V 200
> -o $1_vid_svcd.mpg
>
> to get a file that takes only one 90 min. SVCD.
The last time I tried the 800MB (90min) CD-R media I encountered
compatibility problems (the CD-R drive I had could not reliably
write media larger than 700MB (80min)).
> After 10 hours on my a31p (1 gig ram, 1,7 P4) the file was about 860 MB, and only
> ~63000 from ca 92000 frames were processed.
>
> Any ideas? I calculated the bitrate with the Java-applet on vcdhelp.
Yes, I have several ideas.
First, to speed things up (but almost a factor of 2) change the '-4 1'
to '-4 2'! There is almost no difference in quality but the speed
will be much higher using '-4 2'.
Second, the -q value is too low (will force the encoder to use more
bits, making a larger file). Use either the default (-q 8) or perhaps
even '-q 10'. With a low bitrate ('-b 1800' is low for SVCD format)
you probably need to use a larger -q value.
Third, encode the audio to a lower bitrate than the default 224. SVCDs
can use any audio rate between 32 and 384kbits/sec. Using 160kb/s
audio saves 8KB/s - for 90minutes that works out to 90 * 60 * 8K or
about 40MB. If the audio is encoded at 160kb then adjust the '-B'
value to mpeg2enc of course ('-B 176', 160 + overhead).
Lastly, then add '-N' to the encoder's option list (this is a gentle
noise reduction that will help save bits).
The encoding command should look something like this:
mpeg2enc -f 4 -q 9 -4 2 -2 1 -B 176 -b 1800 -V 200 -o $1_vid_svcd.m2v
Good Luck!
Steven Schultz
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