buffersrc: add const to the AVFrame* argument of av_buffersrc_write_frame()

libavfilter/buffersrc.c

@@ -70,7 +70,7 @@ typedef struct {
         return AVERROR(EINVAL);\
     }
 
-int av_buffersrc_write_frame(AVFilterContext *buffer_filter, AVFrame *frame)
+int av_buffersrc_write_frame(AVFilterContext *buffer_filter, const AVFrame *frame)
 {
     BufferSourceContext *c = buffer_filter->priv;
     AVFilterBufferRef *buf;

libavfilter/buffersrc.h

@@ -45,6 +45,6 @@ int av_buffersrc_buffer(AVFilterContext *s, AVFilterBufferRef *buf);
  * @warning frame data will be memcpy()ed, which may be a big performance
  *          hit. Use av_buffersrc_buffer() to avoid copying the data.
  */
-int av_buffersrc_write_frame(AVFilterContext *s, AVFrame *frame);
+int av_buffersrc_write_frame(AVFilterContext *s, const AVFrame *frame);
 
 #endif /* AVFILTER_BUFFERSRC_H */