On Thu, 20 May 2004, Michel wrote:
> the input avi is 1,4GB. The output mpeg2 is around 3,8 GB. The input
> resolution is 576x320. I watched the output mpeg2 and there is no
> visible difference in quality as far as I can tell. A very good
> algorithm it seems.
bicubic is quite good. even better is a 4 or 5 cycle Sinc-Lanczos ;)
y4mscaler -S option=sinc:5
The times I've scaled up from 320 lines to even 480 the quality to me
was not all that good - perhaps my eyeballs are "too golden" ;)
> It seems the mjpeg-tools has large-file size compiled in. I don't see an
> option for transcode about it, but I saw in their Changelog that a while
> back support for large AVI-files had entered the code. So, I suppose
I think you have encountered a bug in the large AVI file support
though.
You mentioned that the pipeline breaks at ~183000 frames of ~250000
total.
183000/250000 * 1,4GB = 1.024GB
That looks very very close to the 1GB AVI limit.
> it's in there. The command without yuvscaler seems to work..although I
> don't use the "compact" notation of it without the pipes. Only transcode
> ..... -y mpeg2enc,ac3 ...
External scalers are, from what I have seen, of higher quality than
transcode's builtin scaling.
Also you may need to consider the SAR (Sample Aspect Ratio). Many
of the MPEG-4/DivX encodings have been created with 1:1 pixels but
DVDs use Rec.601 pixels which are 59:54 for PAL (and 10:11 for NTSC).
> > The "-O DVD" and "-O SIZE_720x576" are redundant. Once you use
> >
>
> thanks. Good to know that.
Even better get a copy of y4mscaler from
http://www.mir.com/DMG/Software/y4mscaler.html
Then, using no scaling in transcode (or other mpeg-4 to yuv4mpeg2
producing program):
... | y4mscaler -I norm=PAL -I sar=1:1 -O preset=DVD -S option=sinc:4 | ...
That will take into account the square input pixels, the PAL DVD
pixels and frame size and perform any matte or crop operations needed
as well as doing the scaling.
> Can't tell anymore... But the pipeline broke behind transcode. First I
I really think it's transcode breaking the pipe when it hits the
1GB AVI limit - it's producing a partial frame on output and that
is what is causing the following program to emit an error.
> The version before 1.6.2. I'll upgrade...
Good Idea! ;)
Cheers,
Steven Schultz
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