[vdr] Re: A/V sync problems with new drivers

[Steffen Barszus <st_barszus@gmx.de>]

Am Freitag, 11. April 2003 19:36 schrieben Sie:
> Hi Juri,
>
> > Reinhard Walter Buchner wrote:
> > > - The ARM 7 is capable of hardware scaling (pg 34) If Mplayer
> > > could utilize this capability, it could make a lot of people with
> > > low CPU power in their STBs happy. From what I have figured
> > > out of Mplayer it doesn't make use of this feature when doing
> > > an output via -vo mpegpes. However, this will probably only
> > > work with native mpeg 2 input streams ;o((.
> >
> > I heavn't read the document, so I don't really know, what hardware
> > scaling means in this context, but I think, it means the following, what
> > mplayer (or better, mplayer.sh) does use:
> >
> > If you play a video with a resolution of 352x240 (NTSC) or 352x288 (PAL)
> > then the ARM does a hardware scaling to the full NTSC or PAL format
> > (720x480 / 720x576). It does so also for the width, if the height is
> > either 480 (NTSC) or 576 (PAL) and the width is one of the following:
> > PAL:  352 480 528 688 704
> > NTSC: 352 480 512 640 704
>
> Yes, I know your script does this ;o)) From what I saw in the Mplayer
> code, I'm not quite sure if it really does this via hardware. The main
> problem with mplayer is that it is so complex (at least if not more
> than VDR) and the code is "splattered" all over. There is no way for
> *me* to really see if mplayer uses all the hardware capabilities or
> not. The AV711x of course can only do this with mpeg2 frames, so
> any downscaling (or upscaling) of say a divx film is most likely to
> be software based. That is, unless, mplayer (and the whole codec
> stuff behind mplayer) converts the divx to mpeg2 first and then scales
> it. 

Thats not true. It would make no sense to first convert it then scale and 
convert it a second time. Furthermore mplayer does not convert it to mpeg2, 
it makes use of the mpeg1 encoder from ffmpeg.

The splattered code is one of the reason why arpi stops to be the maintainer 
;) and plans to make a new player. 

>I really don't know if they do it this way, because, if they scale it
> before they convert it, they have less data to process, so this might
> be the way mplayer does it, but I *really* truely have no idea.

It is the only way to do it. You can't scale video after encoding w/o 
reencoding. Further the cpuload shows the same. 

Greets

Steffen
-- 
If the human brain were so simple that we could understand it,
we would be so simple we couldn't.
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