On Fri, 18 Mar 2005, E.Chalaron wrote:
> I got rid of my last issues with the telecine acquisition here. Got pnm
> frames, scaled down etc...... filtered, all good. DV files created, look nice.
You're going from 4:4:4 to 4:1:1 (DV) and then to 4:2:0? Hmm, oh -
that's right - for PAL DV is 4:2:0 (almost forgot that ;)).
y4mscaler will of course convert to "420paldv" but I'm not sure that
the rest of the tool chain knows about '420paldv'. Feeding 420paldv
into mpeg2enc is probably not the right thing to do - I think mpeg2enc
wants 420mpeg2.
Or are you converting to NTSC-DV (4:1:1)?
That's not the cause of the...
> And once encoded ... it's terrible.
...terrible but I do think all that resampling/conversion will exact
a price on the quality.
Any particular reason you're converting to DV? That's a lossy process.
> I am using a straight forward command :
>
> yuvdenoise -F -f | mpeg2enc -f 8 -4 2 -2 1 -r 16 -H -g 6 -G 15 -R 0 -D 10
No -q and no --cbr means that -q is defaulted to 8 - and that can be
quite blocky (especially if -H is used which can raise the number of
bits needed).
> acceptable. Results are REALLY getting bad once encoded in mpeg2. It is
> extremly blocky. I am not sure what I am doing wrong but the result is
"-q 8" tends to do that :)
-H is probably not a good idea - the comment about that option makes
mention of high rate (and I don't think 7500 is considered "high")
I think you'd be much better off leaving out the -H and using
"-q 4".
> Any idea ?
Another thing to try is using "--cbr" instead of "-q" - that will
produce a constant bitrate (default 7500) and vary the effective 'q'
as needed to maintain the bitrate.
> I tried to make sure that I was not messing too much with -q, it does not
> seem to affect the result... Or is it because I have a cheap and nasty
Not using -q defaults to 8 unless you request constant bitrate. I think
it's going to be necessary to use -q ;)
Cheers,
Steven Schultz
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