Re: [PATCH ] libv4l: skip false Pixart markers

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 02/01/2010 11:13 PM, Németh Márton wrote:
> From: Márton Németh<nm127@freemail.hu>
>
> The byte sequence 0xff, 0xff, 0xff 0xff is not a real marker to skip, instead
> it is one byte from the image and the following three 0xff bytes might belong
> to a real marker. Modify pixart_fill_nbits() macro to pass the first 0xff byte
> as an image data.
>

Oh, good catch. I'm still seeing the occasional bad frame though :(

While on the subject of the pac7302. I've been playing around a bit, and I have the
feeling that if we were to go for a lower auto gain target (set autogain off and
lower exposure, you can do this ie with v4l2ucp), combined with a gamma correction of
1500 (again use ie v4l2ucp), the images is much better (less over exposed, more
contrast).

Do you agree ?

Regards,

Hans


> Signed-off-by: Márton Németh<nm127@freemail.hu>
> ---
> diff -r f23c5a878fb1 v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c
> --- a/v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c	Mon Feb 01 13:32:46 2010 +0100
> +++ b/v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c	Mon Feb 01 23:05:39 2010 +0100
> @@ -339,10 +339,15 @@
>   	    } \
>   	    break; \
>   	  case 0xff: \
> -	    if (stream[1] == 0xff&&  (stream[2]<  7 || stream[2] == 0xff)) { \
> -	      stream += 3; \
> -	      c = *stream++; \
> -	      break; \
> +	    if (stream[1] == 0xff) { \
> +		if (stream[2]<  7) { \
> +		    stream += 3; \
> +		    c = *stream++; \
> +		    break; \
> +		} else if (stream[2] == 0xff) { \
> +		    /* four 0xff in a row: the first belongs to the image data */ \
> +		    break; \
> +		}\
>   	    } \
>   	    /* Error fall through */ \
>   	  default: \