Re: new release: pre39

On Mon, Aug 04, 2003 at 11:09:32AM +0200, Arpi wrote:
> Hi,
> 
> > On Mon, Aug 04, 2003 at 09:11:31AM +0200, Arpi wrote:
> > > > relative pts, or absolute? With 32bit int, you only have room for
> > > > ~4000 seconds before you wrap....and many movies are longer than that!
> > > 
> > > it's absolute time counter truncated to 32 bits. it's far enough.
> > > no movies encoded at 1/4000 fps...
> > 
> > ??
> 
> the integer 1/1000000 res. counters are used to do timing between 2 frames.
> so unless you have an 1/4000 fps "movie" (i would call it very slow
> slideshow instead) it won't overflow :)

Yes, I see now. :)

> > generating bad timestamps encoding to variable-fps output formats.
> > Also, there's the case where you're working with really long files,
> > where the error could easily get as large as frame durations, so I'd
> > be happier using doubles, at least wherever absolute pts is needed.
> 
> then RTFS mp_image.h ;)

I'm too lame to RTFS. :(

> > By inexact I mean it's not based on the same time base as the file,
> > but rather approximation by float or fixed point number.
> 
> yes, but since realtime timers (usleep, rtc and so on) are 1/1000000 based
> i nee dto convert to that base to do teh actual timing. and no human will
> be able to see the difference between 1us and 1.024 us, but not even 1us and
> 10us i think.

Yeah, should be fine. I'm just paranoid after seeing G1's mencoder do
nonsense like duplicating a bunch of frames only to force itself to
skip frames < 1sec later, generating horrible choppy output files.

> > > no, but it's fun to see, esp. at mixed hard/soft telecined material :)
> > 
> > Ah, but I thought the new code didn't change nominal framerate, just
> > delay rff frames by 1/120 sec...
> 
> actually there is no thing as framerate in g2, only relative pts (or
> duration). so actually it prints 1/duration...
> 
> (it printed duration in ms before, but fps loosk better)

Ah, very cool. This is a nice number to know for encoding from
variable-fps formats like asf into a fixed-fps container. :)

Rich