[MPlayer-dev-eng] mp-G2 pre18 / Video with no sound

Arpi arpi at thot.banki.hu
Tue May 6 01:15:38 CEST 2003


> No, we wish it were that easy... In practice, telecine pattern is
> often not regular. Causes may include scene change/splicing,
> frame duplications to slow down video slightly post-editing, or mixed
> telecine/progressive/interlaced content. When I set out writing this
> stuff, I naively thought it would be simple, but it's a huge mess.
> Anyway, am I correct in assuming that if I multiply all durations by
> 5/4, but don't drop *exactly* one frame out of every 5, A/V sync will
> break?

Just temporarily. There is A-V sync correction based on timestamps, so
if it doesn't happen too often (more than twice per second) it will be
smoothed out.

> If so, I think the simplest fix is to multiply frame durations by 3/2
> when the frame has one of its fields repeated. This will correspond
> exactly to the timing when watching the telecined video on a TV set,
> but it won't be quite as smooth as the perfect 24 fps output would be.

Hmm, yes. So you need to do more math, multiply progressive frames durations
by 30/24 and the duplicated-field frames durations by 30/24/1.5

We'll see when i implement the filter to correct soft-telecined stuff.

> So, I'd rather think of a nicer way to handle it.
> BTW, about detc vs ivtc.... Yes the names are confusing, and yes they

I mean not only those, but there are vf_field, vf_tfields, 
vf_halfpack, vf_il, vf_ilpack and who nows how many other interlacing
related filters. I also guess manpage says 'deinterlace' or inv teel;cine'
for most of them, so you have to do heavy RTFS to find out the differences.
And it's not enough, you also have to learn these names, and try not to
exchange them while using :)

> both exist. They're two different filters that take different
> approaches to removing telecine. vf_ivtc is a much nicer design, IMO,
> and has optimized MMX code. The algorithm in vf_detc, however, may
> work better when the telecine pattern is very regular but the input
> signal is noisy (think analog TV input). Maybe for G2 I'll merge them
> into a single filter with options to use several different algorithms.


A'rpi / Astral & ESP-team

Developer of MPlayer, the Movie Player for Linux - http://www.MPlayerHQ.hu

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