Video Playback virtually impossible on Neo Freerunner? (Re: Video of Qt 4.4 on Neo1973: brings iPhone like graphics)

[Carsten Haitzler (The Rasterman)]

On Sun, 27 Apr 2008 22:48:53 +0000 "Federico Lorenzi" <florenzi at gmail.com>
babbled:

> Well, after doing a few tests, (mainly thanks to ahven and SpeedEvil
> on IRC), the Neo can handle a 160x128 H264 (with CABAC) encoded video
> at 40kbps with a 12kbps audio track. The fun comes in with the
> scaling. Scaling to 320x240 with no frame dropping is possible if I
> encode the video as baseline H264. However, I think the Freerunner,
> especially with a beefier processor and hardware scaling, should
> perform quite a bit better. The scaling seems to give quite a big
> performance hit.

on the freerunner scaling is "free" (no pun intended) so to speak. that means
*IF* you use xvideo - the hardware handles yuv->rgb conversion as well as
scaling. there is a hard limit on the amount of data you can transfer to the
video card per second (about 7.3 m/sec) and as such will limit resolution and
framerate of the source video (as resolution goes up, framerate goes down -
like all things, a trade-off). remember that all time spent copying data to
video memory is time that can't be spent decoding the actual video data if you
copy 7.3m of video to the glamo then you use up 1 second for the copy where you
have no time to do any decoding as copying is not done via dma, and even if we
did do it with dma (which we tried! we really did!), would lock up the memory
bus during this transfer anyway and dma actually proved much slower than using
the cpu to do the copy - even for large chunks of data. less than half the
speed.

so it's all a tradeoff.

> Cheers,
> Federico
> 
> PS) I do not own a Neo, and I'm not an expert on anything
> 
> On 4/27/08, Kristian 'kriss' Mueller <kriss at mput.de> wrote:
> > Hi Christoph
> >
> > Am Donnerstag, den 24.04.2008, 11:19 +0200 schrieb Christoph Witzany:
> > > As I understood Video playback will be virtually impossible on the
> > > freerunner, at least from the sd card (which is the only sensible
> > > location to store videos on the neo ftm).
> >
> > I did some testing on that with GTA01.
> >
> >
> > > Please correct me if I misunderstood.
> >
> > Even with GTA01 it was possible - though the tests I made there are not
> > valid for GTA02 (don't have one yet).
> >
> > What I found out with mplayer is:
> >
> > 1) H.264 will take to much time to decompress (even at low bitrates)
> > 2) SDL will be the fastest way to output without HW acceleration
> > 3) using H.263 (as Youtube does) I could get the best
> >    compression/bitrate/speed ratio
> > 4) using 320x240 and scale to 640x480 (480x640) is doable
> >
> > Some of those findings are documented at the buttom of
> > http://wiki.openmoko.org/index.php?title=Video_Player
> >
> >
> > > If I interpreted Carsten right 640x480 video will
> > > display at 5-10 fps at best, right?
> >
> > Actually with GTA01 I've had 13 fps in fullscreen mode (320x240 ->
> > 480x640) which looked really okay and was viewable.
> >
> > A 640x480 H.263 though with reasonable bitrate took to much cpu-power to
> > decode.
> >
> > Anyway, with GTA02 you should take a try - it seems doable in SW even
> > without 2D acceleration, as it just has more cpu power. - try to start
> > with:
> >
> > mencoder -quiet -ofps 13 -vf scale -zoom -xy 352 -af channels=1:0:0:1:0
> > \
> > -oac lavc -ovc lavc -lavcopts \
> > acodec=mp3:vcodec=h263p:autoaspect=1:vbitrate=200:abitrate=32 \
> > -o <outfile> <infile>
> >
> > mplayer -autosync 30 -vf scale -zoom -xy 640 -vf rotate=1 -sws 0
> > -nodouble \
> > -vo sdl -fs -framedrop <tagetfile>
> >
> >
> > Greetings from Berlin
> >
> > Kristian
> >
> >
> > --
> > /* Web:     http://www.mput.de  | Tel:    +49 (0)170/6692447      *
> >  * Blog:    http://mput.de/blog | ICQ:    93248497                *
> >  * GPG-ID:  4BBB6525 (..2009)   | Jabber: kristian at mput.de        *
> >  * Twitter: kristian_m          | MSN:    mueller.kristian at vdi.de */
> >
> >
> > _______________________________________________
> > Openmoko community mailing list
> > community at lists.openmoko.org
> > http://lists.openmoko.org/mailman/listinfo/community
> >


-- 
Carsten Haitzler (The Rasterman) <raster at openmoko.org>