avfilter_get_audio_buffer_ref_from_frame: check that layout and channels match if they are set

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/avcodec.c

@@ -93,10 +93,16 @@ AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_frame(const AVFrame *frame
                                                             int perms)
 {
     AVFilterBufferRef *samplesref;
+    int64_t layout = av_frame_get_channel_layout(frame);
 
     if(av_frame_get_channels(frame) > 8) // libavfilter does not suport more than 8 channels FIXME, remove once libavfilter is fixed
         return NULL;
 
+    if (layout && av_get_channel_layout_nb_channels(layout) != av_frame_get_channels(frame)) {
+        av_log(0, AV_LOG_ERROR, "Layout indicates a differnt number of channels than actually present\n");
+        return NULL;
+    }
+
     samplesref = avfilter_get_audio_buffer_ref_from_arrays((uint8_t **)frame->data, frame->linesize[0], perms,
                                                   frame->nb_samples, frame->format,
                                                   av_frame_get_channel_layout(frame));