do not override rc_buffer_occupancy if set

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@7641 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

ffmpeg.c

@@ -2868,6 +2868,7 @@ static void new_video_stream(AVFormatContext *oc)
             if(p) p++;
         }
         video_enc->rc_override_count=i;
+        if (!video_enc->rc_initial_buffer_occupancy)
             video_enc->rc_initial_buffer_occupancy = video_enc->rc_buffer_size*3/4;
         video_enc->me_threshold= me_threshold;
         video_enc->intra_dc_precision= intra_dc_precision - 8;