int ff_videotoolbox_alloc_frame(AVCodecContext *avctx, AVFrame *frame);
int ff_videotoolbox_uninit(AVCodecContext *avctx);
-int ff_videotoolbox_buffer_create(VTContext *vtctx, AVFrame *frame);
int ff_videotoolbox_h264_start_frame(AVCodecContext *avctx,
const uint8_t *buffer,
uint32_t size);