In the avfiltergraph of FFmpeg, it is required that all filters within the graph can obtain a format and successfully negotiate for data flow. So, is it allowed for the graph to contain filters that cannot obtain a format? Can these filters be ignored during format negotiation, allowing only the filters that can obtain a format to negotiate successfully? This patch addresses the problem described in this scenario. For example: abuff_src@Music ---> amix --> abuff_sink abuff_src@Ring   In the graph above, We support three playback scenarios at the same time: 1. Only abuff_src@Music needs to be played, and abuff_src@Ring has no data. abuff_src@Ring is ignored during negotiation, abuff_src@Music --> amix --> abuff_sink link negotiation is successful, and playback can be performed; 2. Only abuff_src@Ring needs to be played, and abuff_src@Music has no data. abuff_src@Music is ignored during negotiation, abuff_src@ring --> amix --> abuff_sink link negotiation is successful, and playback can be performed; 3. Both abuff_src@Music and abuff_src@Ring need to be played, and all filters are negotiated successfully and mixed playback is performed. ÑîÑÇÀÚ 269032741@qq.com   ------------------ Original ------------------ From: "ffmpeg-devel"