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vp6: ensure that huffman decoding table is sorted with descending symbol order Previous code worked by pure luck with glibc qsort implementation. patch by Peter Ross pross _at_ xvid _dot_ org

Originally committed as revision 13887 to svn://svn.ffmpeg.org/ffmpeg/trunk

Peter Ross authored on 2008/06/22 22:20:41
Showing 1 changed files

@@ -202,10 +202,11 @@ static void vp6_parse_vector_models(vp56_context_t *s)
                 model->vector_fdv[comp][node] = vp56_rac_gets_nn(c, 7);
 }
 
+/* nodes must ascend by count, but with descending symbol order */
 static int vp6_huff_cmp(const void *va, const void *vb)
 {
     const Node *a = va, *b = vb;
-    return a->count >= b->count;
+    return (a->count - b->count)*16 + (b->sym - a->sym);
 }
 
 static void vp6_build_huff_tree(vp56_context_t *s, uint8_t coeff_model[],

...	...	@@ -202,10 +202,11 @@ static void vp6_parse_vector_models(vp56_context_t *s)
202	202	model->vector_fdv[comp][node] = vp56_rac_gets_nn(c, 7);
203	203	}
204	204
	205	+/* nodes must ascend by count, but with descending symbol order */
205	206	static int vp6_huff_cmp(const void va, const void vb)
206	207	{
207	208	const Node a = va, b = vb;
208		- return a->count >= b->count;
	209	+ return (a->count - b->count)*16 + (b->sym - a->sym);
209	210	}
210	211
211	212	static void vp6_build_huff_tree(vp56_context_t *s, uint8_t coeff_model[],