lavfi: add qp_table_size

This avoid recalculating it and in case w/h changed avoids crashes.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/avcodec.c

@@ -50,6 +50,7 @@ int avfilter_copy_frame_props(AVFilterBufferRef *dst, const AVFrame *src)
             if(!dst->video->qp_table)
                 return AVERROR(ENOMEM);
             dst->video->qp_table_linesize       = src->qstride;
+            dst->video->qp_table_size     = qsize;
             memcpy(dst->video->qp_table, src->qscale_table, qsize);
         }
         break;

libavfilter/avfilter.h

@@ -132,6 +132,7 @@ typedef struct AVFilterBufferRefVideoProps {
     enum AVPictureType pict_type; ///< picture type of the frame
     int key_frame;              ///< 1 -> keyframe, 0-> not
     int qp_table_linesize;                ///< qp_table stride
+    int qp_table_size;            ///< qp_table size
     int8_t *qp_table;             ///< array of Quantization Parameters
 } AVFilterBufferRefVideoProps;
 

libavfilter/buffer.c

@@ -42,7 +42,7 @@ void ff_avfilter_default_free_buffer(AVFilterBuffer *ptr)
 static void copy_video_props(AVFilterBufferRefVideoProps *dst, AVFilterBufferRefVideoProps *src) {
     *dst = *src;
     if (src->qp_table) {
-        int qsize = src->qp_table_linesize ? src->qp_table_linesize * ((src->h+15)/16) : (src->w+15)/16;
+        int qsize = src->qp_table_size;
         dst->qp_table = av_malloc(qsize);
         memcpy(dst->qp_table, src->qp_table, qsize);
     }