[MPlayer-users] TELECINE or not TELECINE?

[Corey Hickey]

Rainer Koehler wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> 
> Thank you very much, Corey and Rich, that was very instructive!
> I hope I'm now able to ask the right questions...
> 

No problem; we all have to start somewhere. Rich, of course, knows a
whole lot more about all this than I do. I'll answer what I can of what
you wrote below.

> 
> For the record (i.e. the archive): The guide at divx.com about 
> interlacing, telecine etc. is now at
> http://www.divx.com/support/guides/guide.php?gid=10
> (at least I think that's what you meant).
> 

Yeah, looks like they changed it. Thanks.

> 
>>>Play that part of the video with -fps 1 and look closely at the
>>>pattern of interlaced frames. If every single frame is interlaced, then
>>>there's no telecine to remove, and you'll have to decide between using
>>>a deinterlacing filter (pp=lb, etc.) or just leaving those few frames
>>>interlaced.
> 
> 
> I looked *very* closely at my file (I dumped the first seconds to PNG
> files).  I find no trace of interlacing in the telecined part, but
> some (not all) frames in the progressive part are interlaced.  Am I
> right that this is one of those movies with hard and soft-telecine
> mixed?
> 

Yes, you are correct. The confusing part, as you may have noticed, is
that when mplayer says TELECINE, what you see looks progressive, and
when mplayer says progressive, what you see looks telecined.

The reason behind this is that mplayer is reporting on flags it finds in
the mpeg2 data. If the flag says "telecine", that means the video source
has not yet been telecined, and needs to be. If the flag says
"progressive", then the video has already been telecined, and doesn't
need to be (or, the video was shot at 29.97fps and is already interlaced
without having been telecined.

> [telecine output snipped]
> 
> If I understand this correctly, the first number after "telecine ="
> indicates how long a frame should be displayed, so 1.5 should mean
> that the frame should be displayed longer to do the soft-telecine.
> Nearly all of the frames in the progressive sequence have "telecine =
> 1.0", but some of them look interlaced, so they are hard-telecined.
> Am I right so far?
> 

Mmm... probably. Rich could say for sure.

> 
>>>If you eventually choose to use one of the telecine filters, you should
>>>make sure to apply them before cropping/scaling. Doing otherise can be
>>>problematic. For example:
>>>-vf softpulldown,ivtc=1,crop=708:358:6:62,scale=672:288
> 
> 
>>Nice advice. You can also use the pullup filter now (it supports mixed
>>hard+soft telecine!) but it won't (yet) work with -ofps 23.876. I'll
>>fix that later if I can think clearly enough to work out the
>>input:ouput frame ratio regulation right...
> 
> 
> So, should I use -ofps at all?  And if yes, with which framerate?

Yes, use -ofps 23.976. I would recommend that you use softpulldown, then
ivtc=1, as I wrote in my first mail. I've actually had some success with
pullup and -ofps, but that combination doesn't yet seem to be resilient
enough to not crash under some circumstances.

> Or would the right way to figure out the output framerate be to
> average all the 1.0s and 1.5s in the debug output and divide the input
> framerate by it?
> 

I'm not sure what you're getting at here, but once you remove the
telecine, everything should be 23.976 fps. If there still happens to
exist some 29.97 fps interlaced video, frames will be dropped from it.


> Thanks again,
> Rainer
> 

No problem,
Corey