+ *
+ * The list of pixel formats must contain at least one valid entry, and is
+ * terminated with AV_PIX_FMT_NONE. If it is possible to decode to software,
+ * the last entry in the list must be the most accurate software format.
+ * If it is not possible to decode to software, AVCodecContext.sw_pix_fmt
+ * must be set before calling this function.