Frame rate of the stream on the link, or 1/0 if unknown;
if left to 0/0, will be automatically be copied from the first input
of the source filter if it exists.
Sources should set it to the best estimation of the real frame rate.
Filters should update it if necessary depending on their function.
Sinks can use it to set a default output frame rate.
It is similar to the r_frame_rate field in AVStream.
Frame rate of the stream on the link, or 1/0 if unknown; if left to 0/0, will be automatically be copied from the first input of the source filter if it exists.
Sources should set it to the best estimation of the real frame rate. Filters should update it if necessary depending on their function. Sinks can use it to set a default output frame rate. It is similar to the r_frame_rate field in AVStream.