[GEM-dev] GEM dv support

Franz Hildgen franz at sat.qc.ca
Tue Jan 13 18:50:20 CET 2004


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Hi,

I've modified videoDV4L.cpp so it can decode DV stream (from a DV 
camera) within GEM, I had to change/add a few lines to make it work.

I do have a few questions though, the frame buffer seems quite large 
decodedbuf = new unsigned char[725*576*40];

I believe that a size of 720*576*3 should be enough for the decoding, 
and it is.


The performance is not real time yet, the decoding in software is really 
expensive. Am I the only one experiencing that kind of performance.



I see two ways of boosting the performance.

First if libdv could output a RGBA image, we wouldn't have to convert it 
from RGB to RGBA.
And second, if libdv could output a frame at half the DV resolution, so 
it will be 360x240 (or 360x288 for PAL). The video quality should be 
there and the performance should be much better.

Also I've heard that the dv decoding in ffmpef/libavcodec is faster than 
in libdv, have anyone try to implement it ?


thank you

franz


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