@@ -134,6 +134,9 @@ static int attribute_align_arg av_buffersrc_add_frame_internal(AVFilterContext *

                                  frame->format);

         break;

     case AVMEDIA_TYPE_AUDIO:

+        /* For layouts unknown on input but known on link after negotiation. */

+        if (!frame->channel_layout)

+            frame->channel_layout = s->channel_layout;

         CHECK_AUDIO_PARAM_CHANGE(ctx, s, frame->sample_rate, frame->channel_layout,

                                  frame->format);

         break;