Re: [libdc1394-devel] bug in _dc1394_basic_format7_setup

[Boris Z. <bs_...@ya...>]

Hi
Damien Douxchamps <da...@do...> wrote: Hi Boris,

On Mon, 2006-01-02 at 01:26 -0800, Boris Zingerman wrote:
>  Hi 
> 
> Considering  libdc1394-2.0.0-pre5
> 
> 1. There is apparently bug in _dc1394_basic_format7_setup which
> causes dc1394_dma_setup_format7_capture to failure even when
> provided with correct ROI (region of interest ) dimensions, due to
> incorrect image position/size updates order. For example if you
> start with full camera ROI and then change it to anything with 
> non-zero x or y offset ( and smaller width/height of course to make
> ROI legal ) dc1394_dma_setup_format7_capture will fail. 
> I've written patch (attached) that solves this problem. 
> It seems to work for me. 

This could be a problem indeed. Thanks for spotting it. I checked your
patch but I think there's an easier way to handle this: always set the
image position to (0,0) before doing the size/position adjustments.
Would it be equivalent to the patch you sent?

 Sorry, I think I've misunderstood you in my previous posting. 
 If this is done in the library and not by the user it will certainly work.
  _dc1394_basic_format7_setup must do it in 3 steps : set position to (0,0),
 change size and then set position to the desired values. In the patch I've
 tried to optimize it because in many cases it can be done in 2 steps, thus
 saving one system call, but I've missed that for this to be done we must
 retrieve current position/size that is not done by the function on the
 regular basis, which makes my solution worse than your simple one :-)
 
 best regards
 Boris
 
  

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