Acceleration in our pockets

Sat Jun 14 04:34:03 CEST 2008

On Fri, 13 Jun 2008 16:56:03 +0200 Peter Nijs <peter at familienijs.be> babbled:

> I'm still confused about the clame somebody made he had sent a 320x240 mpeg4 
> stream to the glamo and got 21fps when the data came from internal flash 
> while the same stream from sd gave 19 fps. <my comprehension>. I assume the 
> data HAS to pass the cpu when it comes from internal flash, because the flash 
> and the glamo are on a different bus. When the stream came from the sd card 
> it passed the graphics bus twice because dma doesn't work. A well compressed 

it didnt pass an mp4 stream to the glamo. it passes yuv data. cpu decodes mp4
to yuv frames. frames are uploaded to glamo as normal (read up on xvideo and
fourcc). the mp4 file coming from sd card comes from the cd card on the glamo
to system ram - gets decoded, then goes back to glamo as yuv data. btw - it's 7
megabytes - not megabits that is the bandwidth (7.3 is what i measured).

there is no usable dma so all copies are done by cpu.

> 320x240 mpeg4 stream takes 500kbit/s max with sound. So twice this doesn't 
> chocke any bus. The cpu also has time enough to do other things here.</my 
> comprehension</a> So how could these framerates be so low? The site of the 
> glamo claims it can do 30fps on VGA. Which maybe brings the needed bus speed 
> to 1Mbit/s in the worst case with dma and 2Mbit without.

sorry - math is based on wrong assumptions. see above :)

> Peter
> 
> > > [...]> > > with the glamo you need to be careful what you do
> > >
> > > > > and how you do it. if you can
> > > > >
> > > > > > keep something entirely within the glamo - it
> > > > >
> > > > > should be ok. so things like
> > > > >
> > > > > > uploaded pixmaps and then blitting them around is
> > > > >
> > > > > ok. video decode is another
> > > > >
> > > > > > matter entirely. the glamo has an mpeg4 decoder on
> > > > >
> > > > > it - but we don't have any
> > > > >
> > > > > > api to access that directly/sanely and just feed
> > > > >
> > > > > it an mpeg4 stream. any other
> > > > >
> > > > > > codec has to be done on the cpu anyway and
> > > > >
> > > > > uploaded across the bus as yuv data.[...]
> > >
> > > [...]that is quite possible. 320x240 video would be sane possibly if the
> > > source is internal flash instead of SD or maybe 802.11.[...]
> > >
> > > [...]but the problem here
> > > is that xv does not provide a way to do this sanely (stream just mpeg4
> > > data to x so it decodes in hardware). the graphics chip (glamo) can
> > > decode mpeg4 itself, but we dont have the time or resources to do this
> > > properly ourselves. you are free to do it yourself as we provide all the
> > > code, but you would need to reverse-engineer the graphics chip or hope
> > > that graphics documentation can be made public. right now you need an NDA
> > > to see the docs.[...]
> > >
> > > [...]what freerunner *IS* good at is nice high resolution still images.
> > > it is NOT good at motion (animation). that's possibly the simplest way i
> > > know to describe its graphics :) great for ebook and text reading. great
> > > for your high-res photos. don't expect a media-center out of it with
> > > swooshy bits and fanciness and video at wonderful quality and resolutions
> > > and framerates.[...]
> > >
> > > [...]see my other mail. 320x240 at 30fps is not possible. off sd card about
> > > 19fps is the limit @ 320x240. 21fps if from internal flash. i did actual
> > > tests. mpeg4 video.[...]
> > >
> > > --- El vie, 13/6/08, Carsten Haitzler <raster at openmoko.org> escribió:
> > > > De: Carsten Haitzler <raster at openmoko.org>
> > > > Asunto: Re: Acceleration in our pockets
> > > > Para: dsamblas at yahoo.es, "List for Openmoko community discussion"
> > > > <community at lists.openmoko.org> CC: "David Samblas Martinez"
> > > > <dsamblas at yahoo.es> Fecha: viernes, 13 junio, 2008 2:47
> > > > On Thu, 12 Jun 2008 19:22:30 +0000 (GMT) David Samblas
> > > > Martinez
> > > >
> > > > <dsamblas at yahoo.es> babbled:
> > > > > Hehehe definitively you have something to say :)
> > > > > oops I thought that I have erased this final this so
> > > >
> > > > unfortunate sentence  so
> > > >
> > > > > please accept my apologizes lets joy the fact that the
> > > >
> > > > glamo will not be a
> > > >
> > > > > wasted chip
> > > >
> > > > it never was wasted, but it's not the ultimate solution
> > > > to everything either.
> > > > i'm still wondering where i was so "wrong"?
> > > >
> > > > > --- El jue, 12/6/08, Carsten Haitzler
> > > >
> > > > <raster at openmoko.org> escribió:
> > > > > > De: Carsten Haitzler <raster at openmoko.org>
> > > > > > Asunto: Re: Acceleration in our pockets
> > > > > > Para: dsamblas at yahoo.es, "List for Openmoko
> > > >
> > > > community discussion"
> > > >
> > > > > > <community at lists.openmoko.org> CC:
> > > >
> > > > "David Samblas Martinez"
> > > >
> > > > > > <dsamblas at yahoo.es> Fecha: jueves, 12
> > > >
> > > > junio, 2008 6:58
> > > >
> > > > > > On Thu, 12 Jun 2008 14:52:07 +0000 (GMT) David
> > > >
> > > > Samblas
> > > >
> > > > > > Martinez
> > > > > > <dsamblas at yahoo.es> babbled:
> > > > > >
> > > > > > nb - i codec only - and i also used mplayer at
> > > >
> > > > the time.
> > > >
> > > > > > mpeg1, mpeg2, not to
> > > > > > mention a myriad of other codecs won't work
> > > >
> > > > there, and
> > > >
> > > > > > it still only producing
> > > > > > qvga video.
> > > > > >
> > > > > > if you do follow prior threads on this, you will
> > > >
> > > > notice
> > > >
> > > > > > that i never covered
> > > > > > the mp3 decode of the glamo. that's always
> > > >
> > > > possible,
> > > >
> > > > > > but as such to do well
> > > > > > would need a generic codec-level api supporting
> > > >
> > > > it - like
> > > >
> > > > > > openmax.
> > > > > >
> > > > > > > I copy & paste an very interesting
> > > >
> > > > comment from
> > > >
> > > > > > balrog ,seems that I have
> > > > > >
> > > > > > > become his(totally voluntary) mail list
> > > >
> > > > assistant ;)
> > > >
> > > > > > > Rasterman..... 352x288 25 fps..... something
> > > >
> > > > to say?
> > > >
> > > > > > > --------------Begin of
> > > >
> > > > comment-----------------------
> > > >
> > > > > > > #  balrog Says:
> > > > > > > June 11, 2008 at 4:20 am
> > > > > > >
> > > > > > > Mikko: I hope we’ll eventually see more
> > > >
> > > > than just
> > > >
> > > > > > MPEG support on the Glamo
> > > > > >
> > > > > > > (3D stuff etc). Regarding QVGA at this
> > > >
> > > > moment it’s a
> > > >
> > > > > > conjecture… and at this
> > > > > >
> > > > > > > moment it’s confirmed. I’ve just tried
> > > >
> > > > QVGA and
> > > >
> > > > > > while the colours became a
> > > > > >
> > > > > > > bit undersaturated and gamma seems to be too
> > > >
> > > > high, I
> > > >
> > > > > > got full 25fps playback
> > > > > >
> > > > > > > both straight and with rotation, hw-scalled
> > > >
> > > > from
> > > >
> > > > > > 352×288 to 240×320 or
> > > > > >
> > > > > > > 320×240. Unfortunately tslib seems to not
> > > >
> > > > have
> > > >
> > > > > > noticed the change and still
> > > > > >
> > > > > > > reports touch coords in 0…640 range.
> > > > > > >
> > > > > > > i_m_bison: Darude_-_Feel_the_beat.mp4 (the
> > > >
> > > > video is
> > > >
> > > > > > ok, the music not so
> > > > > >
> > > > > > > much:))
> > > > > > >
> > > > > > > tuXXX: I was wondering about that too, but
> > > >
> > > > rather MPEG
> > > >
> > > > > > decoding on the CPU
> > > > > >
> > > > > > > and scaling/rotation on Glamo - this would
> > > >
> > > > allow us to
> > > >
> > > > > > do more stuff
> > > > > >
> > > > > > > concurrently. The other way, as Mikko notes
> > > >
> > > > you
> > > >
> > > > > > transfer the video to the
> > > > > >
> > > > > > > VRAM, then back to the RAM and then back to
> > > >
> > > > the VRAM
> > > >
> > > > > > and the bus becomes a
> > > > > >
> > > > > > > bottleneck. In the current setup and normal
> > > >
> > > > usage I
> > > >
> > > > > > don’t agree with Raster
> > > > > >
> > > > > > > that 7M/s is a bottleneck, it’s rather
> > > >
> > > > hard to
> > > >
> > > > > > saturate with normal X usage
> > > > > >
> > > > > > > even coupled with SD card traffic etc.
> > > > > > > ----------End of
> > > >
> > > > comment------------------------------
> > > >
> > > > > > > Raster, I'm really happy that you where
> > > >
> > > > so wrong
> > > >
> > > > > > at this topic
> > > > > >
> > > > > > > --- El jue, 12/6/08, Joerg Reisenweber
> > > > > >
> > > > > > <joerg at openmoko.org> escribió:
> > > > > > > > De: Joerg Reisenweber
> > > >
> > > > <joerg at openmoko.org>
> > > >
> > > > > > > > Asunto: Re: Acceleration in our pockets
> > > > > > > > Para: community at lists.openmoko.org
> > > > > > > > CC: "Peter Nijs"
> > > > > >
> > > > > > <peter at familienijs.be>
> > > > > >
> > > > > > > > Fecha: jueves, 12 junio, 2008 2:37
> > > > > > > > Am Do  12. Juni 2008 schrieb Peter
> > > >
> > > > Nijs:
> > > > > > > > > Isn't the shared bus an
> > > >
> > > > advantage
> > > >
> > > > > > because now it
> > > > > >
> > > > > > > > can use DMA? Maybe that's
> > > > > > > >
> > > > > > > > > why
> > > > > > > > > it is possible to hook up an
> > > >
> > > > sd-card to the
> > > >
> > > > > > glamo
> > > > > >
> > > > > > > > anyway. I see no other
> > > > > > > >
> > > > > > > > > explanation why one would put an
> > > >
> > > > sd
> > > >
> > > > > > cardreader in a
> > > > > >
> > > > > > > > graphics ship. Please
> > > > > > > >
> > > > > > > > > tell me if and why I'm wrong.
> > > > > > > > >
> > > > > > > > > Peter
> > > > > > > >
> > > > > > > > Good point. Would make perfect sense...
> > > >
> > > > /j_______________________________________________
> > > >
> > > > > > > > Openmoko community mailing list
> > > > > > > > community at lists.openmoko.org
> > > >
> > > > http://lists.openmoko.org/mailman/listinfo/community
> > > >
> > > >
> > > >
> > > > ______________________________________________
> > > >
> > > > > > > Enviado desde Correo Yahoo! La bandeja de
> > > >
> > > > entrada más
> > > >
> > > > > > inteligente.
> > > >
> > > > _______________________________________________
> > > >
> > > > > > > Openmoko community mailing list
> > > > > > > community at lists.openmoko.org
> > > >
> > > > http://lists.openmoko.org/mailman/listinfo/community
> > > >
> > > > > > --
> > > > > > Carsten Haitzler (The Rasterman)
> > > > > > <raster at openmoko.org>
> > > > >
> > > > >       ______________________________________________
> > > > > Enviado desde Correo Yahoo! La bandeja de entrada más
> > > >
> > > > inteligente.
> > > >
> > > > > _______________________________________________
> > > > > Openmoko community mailing list
> > > > > community at lists.openmoko.org
> > > > > http://lists.openmoko.org/mailman/listinfo/community
> > > >
> > > > --
> > > > Carsten Haitzler (The Rasterman)
> > > > <raster at openmoko.org>
> > >
> > >       ______________________________________________
> > > Enviado desde Correo Yahoo! La bandeja de entrada más inteligente.
> 
> 
> 

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