[MPlayer-users] show interlaced/progressive info..

[D Richard Felker III]

On Thu, Nov 13, 2003 at 08:12:58PM +0200, Tuukka Toivonen wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Thu, 13 Nov 2003, D Richard Felker III wrote:
> 
> >> > By decoding the video and guessing. Not acceptable.
> >> Acceptable
> 
> I think it's acceptable and even a good idea too, but...
> 
> >Even if the guessing part were acceptable, the decoding part isn't.
> >You can't go and decode a big block of video at startup just to print
> >information. It's way too costly in startup time and messes up the
> 
> ... I agree with this too. Instead there should be a "dummy" filter
> (-vf) that doesn't do anything to the video but just displays whether
> it thinks it's interlaced or not. Or even better, display that in
> the beginning and whenever interlaced video changes into non-interlaced
> or vice versa, report that and the time.

This is certainly acceptable. Feel free to send patch! :))

> >> because mplayer/mencoder can sometimes better guess if a video
> >> is interlaced than a human eye.
> >It can? Would you care to show me how?
> 
> Yeah, just come to look from my text-terminal....

I meant: would you care to show me some code that determines reliably
whether video is interlaced or not? I tried many many times when
working on inverse telecine, and failed every time....and that was
when I even had the added benefit of being able to compare against
non-interlaced frames in most cases!

> (why do you think computers were invented in the first hand, if not
> automatizing things?)

Automating well-defined mathematical processes. Replicating the
ability of the human eye/visual nerves/brain to identify qualities
like interlacing should be possible, but it's extremely difficult and
not a task well-suited to computers.

> >BTW, you should always assume TV captures are interlaced unless you're
> >sure the original came from film or animation.
> 
> If trying to deinterlace noninterlaced video, will it decrease image
> quality? My guess/hope is that most of the time it doesn't.

Depends on which filter you use. If you use li, ci, or fd, it will
completely destroy the quality. Using lb or l5 shouldn't hurt much,
just add a little blurring. Using md won't hurt too much either, but
it will create ugly artefacts around sharp details.

> A bit off the topic, it would be nice if filters could be changed during
> playback/encoding based on frame number, just like quantization parameter
> can be changed with libavcodec. Or is it already possible, I don't think
> so?

Wait for g2... :)

> Hmm... and when will mplayer be able to read Broadcast2000 *.htal files,
> that would save 120 GB of my disk space?-)

What are .htal files? Maybe someone could add support, but most
MPlayer developers aren't too interested in stuff by the author of
bc2k since he has a reputation for making buggy programs that generate
broken, incompatible files...

Rich