函数 av_frame_copy 

pub unsafe extern "C" fn av_frame_copy(
    dst: *mut AVFrame,
    src: *const AVFrame,
) -> c_int

Copy the frame data from src to dst.

This function does not allocate anything, dst must be already initialized and allocated with the same parameters as src.

This function only copies the frame data (i.e. the contents of the data / extended data arrays), not any other properties.

@return >= 0 on success, a negative AVERROR on error.