+ /* skip & 0x80 appears to mean 'start a new line', which can be interpreted
+ * as 'go to next line' during the decoding of a frame but is 'go to first
+ * line' at the beginning. Since we always interpret it as 'go to next line'
+ * in the decoding loop (which makes code simpler/faster), the first line
+ * would not be counted, so we count one more.
+ * See: https://ffmpeg.org/trac/ffmpeg/ticket/226
+ * In the following decoding loop, row_ptr will be the position of the
+ * _next_ row. */
+ lines_to_change++;