[MEncoder-users] ivtc using mencoder

[Late Date]

Thanks again for the help, Mike.

I seem to have something that's at least usable.  Here's the command I used:

mencoder 24p000.m2t -vf pullup -ofps 24000/1001 -oac copy -ovc lavc
-lavcopts vcodec=mpeg2video:vbitrate=24000000:aspect=16/9 -o output.mpg

I wonder if I have the "correct" bitrate setting.  The original bitrate was:
25000.0 kbps (3125.0 kbyte/s)

mencoder's maximum allowable bitrate is "only" 24000000 hence I went with
that.  Here's what's reported by mplayer when I play the new output.mpg:

16384.9 kbps (2000.1 kbyte/s)

Is there any way I can "bump up" that bitrate :-)

I am guessing that this question will pop up a lot in the near future.
Maybe not so much on this forum, but it in the various AV forums.  The new
Canon HV20 just came out (and I just bought it *before* finding out about
this) and this seems to me like a real problem for 24P processing.  Having
to pulldown and reencode the original in order to get at the "true 24P"
seems to me (a novice, I admit) like a lossy operation.  I imagine I will
have to dump it into a raw stream; if I do that, will I suffer any loss in
picture quality?

Chris




On 3/28/07, Mike Hodson <mystica at gmail.com> wrote:
>
> > Thanks for the reassurance, Mike.  You are correct that the -vf pullup
> seems
> > to display the video correctly.  This is good news.  But is there a way
> to
> > issue the following parms (-vf pullup -ofps 24000/1001) without
> re-encoding,
> > i.e., perform *only* the ivtc with no loss?
> No, as the video was originally saved in full 60i format. Granted, the
> camera only was active for 24 frames, it hard-telecined into the mpeg
> video.
>
> > Obviously, I have no idea how to use this tool at all, because my first
> > instinct was to try this:
> >
> > mencoder -vf pullup -ofps 24000/1001 24p000.m2t -oac copy -ovc copy -o
> > output.m2t
> >
> > which produces a horrible output with artificats everywhere :-)  What
> else
> > can I try?
>
> Unfortunately you must re-encode the video, so ovc copy will not work.
> -oac copy will be fine.
>
> You will want to look at the libavcodec parameters, -oac lavc
> -lavcopts and such.  As your input video is HD, going to a raw-dv
> format while being the best way at preserving quality will be
> extremely large, but easy to edit.  You may consider this.
>
> Otherwise, re-encoding to mpeg2 isnt a bad option, you will want to
> set your vcodec=mpeg2, keep your vbitrate at or possibly slightly
> higher than the input (and don't be alarmed if lavc is able to make
> the output file smaller, even if you specify a maximum bitrate higher,
> it is quite efficient, and converting from interlace to progressive
> tends to reduce bitrate) and check the mpegopts parameter as well.
>
> Mike
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