On Thu, May 26, 2011 at 05:48:07PM -0700, Dan Dennedy wrote:
> On Thu, May 26, 2011 at 5:38 PM, Ian Lynagh <[email protected]> wrote:
> > On Thu, May 26, 2011 at 11:47:49AM -0700, Dan Dennedy wrote:
> >>
> >> And it is not capable of interlacing/weaving a 50p input into a 50i
> >> output.
> >
> > But it can do 50p -> 25i (e.g. DVD)?
> 
> Yes, from 50p *AV file* to a 25 fps interlaced project/encoding (50i
> means the same but refers to vertical frequency in Hz, not frames per
> second).

Ah, sorry, I think I was confused and PAL DVDs are 50i, not 25i. This
stuff makes my head hurt!

So if I understand correctly, MLT can do the conversion, but other tools
might do it better. Another advantage of rendering as 50p with
kdenlive/melt, and then having the option of using another tool to
convert to DVD format, I guess!



I'm still having trouble rendering, though. I'd like to make a lossless
1080/50p profile, so I tried various things, e.g. using x264 with crf=0
(mentioned on http://mltframework.org/twiki/bin/view/MLT/ConsumerAvformat)
like so:

    melt untitled.mp4 -profile atsc_1080p_50 -consumer 
avformat:/home/ian/kdenlive/untitled2.mp4 progress=1 f=mp4 acodec=ac3 ab=448k 
ar=48000 ac=2 vcodec=libx264 crf=0 preset=placebo no-interlaced 
profile=atsc_1080p_50 threads=1 real_time=-1

but the result is definitely lossy. In fact, even if I do

    melt -verbose script003.sh.mlt -profile atsc_1080p_50 trellis=0 -consumer 
avformat:/home/ian/kdenlive/untitled2.mp4 trellis=0 progress=1 f=mp4 trellis=0 
vcodec=libx264 trellis=0

the output includes "trellis=1", so I think I must be passing arguments
incorrectly?

Hmm, using cqp=0 looks a lot better, but still isn't lossless according
to ffmpeg -f framemd5.



I also see that atsc_1080p_50 has colorspace 709, while dv_pal_wide has
601. Is that going to cause me any problems? How can I tell what
colourspace my inputs use?



Sorry for all the beginner questions!


Thanks
Ian


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