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[OpenDivX] OpenDivX Decoder ->OpenDivX Daily Forum Digest



OpenDivX Decoder ->OpenDivX Daily Forum Digest



Topic:		Decore Options to optimize for smaller devices
Author:		mindpower
Posted:		 2001-02-26 04:51
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Ok, I found that the yuv2RGB565 variant is already compatible with iPAQs
display buffer. Only problem: the image is upside down.

So I change my above request to this: 
- image flipping option to do so while decoding
- image resizing would still be great (at deconding time)
- dithering would be nice, but so far it is not essential, the video
looks great without it and without postprocessing, too.


Topic:		Faster code
Author:		mindpower
Posted:		 2001-02-26 05:01
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I am about to start to assembly-optimize vital parts of decore for
StrongARM (iPAQ)

Can anyone - who profiled the C code - tell me which routines take the
longest and thus would benefit the most from assembler?

cheers
Mindpower


Topic:		DirectShow filter and relative problems
Author:		vn04697
Posted:		 2001-02-26 09:33
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May be it will be interesting to you: VIDEOINFOHEADER2 also doesn't work
on my NVIDIA TNT2 card. I was forced to drop call to
ConvertVideoInfoToVideoInfo2() in GetMediaType().

Quote:
On 2001-02-23 21:50, e7abe7a wrote:
If you haven't already noticed we have released a DirectShow filter.

The DirectShow filter has a couple of problems... I still didn't figure
out how to solve them so I'm posting these known issues on the forum. I
hope some good guy can come out with some suggestion.

1) The filter uses the VIDEOINFOHEADER2 structure. This solves an
incompatibility problem between the way that the GUI and DirectDraw
interpret the field biHeight of the BITMAPINFOHEADER structure...
without this fix sometimes the output bitmap appears reversed until the
decoder reaches a keyframe. By the way... this structure seems to work
only with an Overlay Mixer filter connected to the output pin of the
DivXFilter and some graphic card don't like this. For example, on the
i810 graphic chip the filter can't work.

2) WMP goes in deadlock when I click on stop during the playback. This
fact made me crazy today ;-( Since the filter is overriden from the
CVideoTransform basic class I suppose that all the thread/critical
section management should be done in the base class for me. I'm so
wrong?

Thanks!




Topic:		Faster code
Author:		eagle
Posted:		 2001-02-26 10:44
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mcmab:  you can email stuff to me at <a
href="mailto:[email protected]";
target="_new">[email protected]</a> but I can't promise a quick
turnaround as I'm very busy right now.  Unless of course you can tell me
that your changes make the code run 300% faster 

I was at Soton uni six years ago - when were you there?


Mindpower:  The iDCT and motion compensation parts usually need the most
horsepower.  However, I wouldn't recommend that you start on any
hard-core optimisiation without some means of measuring your changes.
The GNU profiler, gprof, is available for most platforms and is very
useful.



Topic:		Faster code
Author:		mcmab
Posted:		 2001-02-26 12:22
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It will be sent today.

300%? Well if we assume that the speed of the program is determined by
memory reads - which looks likely to be the case - the above code, as
noted does 64 reads.  In contrast the original code did 1024 reads to
accomplish the same result.  That piece of code could be 1000% faster
IMHO.

I was at Soton 81-86.  I lived in a house that stood where the back
carpark of the new electronics bldg is located.  I presume you were in
Electronics/CS? My friend managed the project that created the newest
Electronics facility, and I'm proud of him - its a fine job.  Note
especially the "porthole" type windows that echo Soton's maritime
history.  While there I pioneered data acquisition on small Unix boxes,
Z80 & 68000.  Hence my strong background in assembler and the then new
"C" language.


Topic:		DirectShow filter and relative problems
Author:		e7abe7a
Posted:		 2001-02-26 13:19
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Mmmmh... Did you try to download the last driver for your graphic card
before going back to VIDEOINFO? In wich mode is working the renderer
now? RGB?


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