For planar audio which requires more than AV_NUM_DATA_POINTERS
AVBufferRef pointers, this array will hold all the references which
cannot fit into AVFrame.buf.
Note that this is different from AVFrame.extended_data, which always
contains all the pointers. This array only contains the extra pointers,
which cannot fit into AVFrame.buf.
This array is always allocated using av_malloc() by whoever constructs
the frame. It is freed in av_frame_unref().
For planar audio which requires more than AV_NUM_DATA_POINTERS AVBufferRef pointers, this array will hold all the references which cannot fit into AVFrame.buf.
Note that this is different from AVFrame.extended_data, which always contains all the pointers. This array only contains the extra pointers, which cannot fit into AVFrame.buf.
This array is always allocated using av_malloc() by whoever constructs the frame. It is freed in av_frame_unref().