[Ffmpeg-devel] [PATCH] watermark.c optimizations for single-frame input (previous patch included)

[Michael Niedermayer]

Hi

On Fri, Oct 20, 2006 at 04:41:41PM +0300, Mihail Stoyanov wrote:
> This patch optimizes watermark.c in 2 ways
> 1. Checks if the current pixel RGB (of the input image) is equal to the 
> threshold before doing any other calculations, thus skipping useless 
> itterations.
> 
> 2. When using single-frame watermark input...
> Checks the starting & ending coordinates (actually rectangle) of the actual 
> watermark (inside the watermark input) using threshold comparison.
> In that way only the area which contains the actual watermark is applied 
> over the movie source reducing the itterations - "for (y...)" & "for 
> (x...)" and greatly improving the covert times.
> It also have checks if the watermark source is multi-frame and disables the 
> optimization
> 
> NOTE: These optimizations are applied ONLY if you are using mode 0 (the 
> default)
> 
> Benchmarks
> --------------------------
> Original watermark.c
> -> Convert time: 00:31
> 
> Patched watermark.c when using multi-frame watermark source (a.k.a animated 
> images or movies)
> -> Convert time: 00:26
> 
> Patched watermark.c when using single-frame watermark source (a.k.a. image)
> -> Convert time: 00:18

great


[...]

> @@ -140,6 +148,10 @@
>      ci->thrR = 0x80;
>      ci->thrG = 0x80;
>      ci->thrB = 0x80;
> +    ci->x1 = ci->y1 = 10000; // it's ugly, i know :)

INT_MAX


[...]
>      }
> +    if (ci->do_optimize) {
> +	start_x = ci->x1;
> +	start_y = ci->y1;
> +	end_x = ci->x2;
> +	end_y = ci->y2;
> +    }

tabs are not allowed in ffmpeg (they tend cause a big mess as not everyone
uses 8space tabs)


[...]
> +	    if (thrR == (int)((pixelm >> 16) & 0xff) &&
> +		thrG == (int)((pixelm >> 8) & 0xff) && 
> +		thrB == (int)((pixelm >> 0) & 0xff)) {

precalculate thr= thrB + (thrG<<8) + (thrR<<16)
and then use if(thr == pixelm)
or
if(thr == (pixelm & 0xFFFFFF)) 
or something like that

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is