A pool from which the frames are allocated by av_hwframe_get_buffer().
This field may be set by the caller before calling av_hwframe_ctx_init().
The buffers returned by calling av_buffer_pool_get() on this pool must
have the properties described in the documentation in the corresponding hw
type's header (hwcontext_*.h). The pool will be freed strictly before
this struct's free() callback is invoked.
This field may be NULL, then libavutil will attempt to allocate a pool
internally. Note that certain device types enforce pools allocated at
fixed size (frame count), which cannot be extended dynamically. In such a
case, initial_pool_size must be set appropriately.
A pool from which the frames are allocated by av_hwframe_get_buffer(). This field may be set by the caller before calling av_hwframe_ctx_init(). The buffers returned by calling av_buffer_pool_get() on this pool must have the properties described in the documentation in the corresponding hw type's header (hwcontext_*.h). The pool will be freed strictly before this struct's free() callback is invoked.
This field may be NULL, then libavutil will attempt to allocate a pool internally. Note that certain device types enforce pools allocated at fixed size (frame count), which cannot be extended dynamically. In such a case, initial_pool_size must be set appropriately.