/** Construct a PictureAsset, generating the MXF from the JPEG2000 files.
* This may take some time; progress is indicated by emission of the Progress signal.
- * @param files Pathnames of JPEG2000 files, in frame order.
+ * @param get_path Functor which returns a JPEG2000 file path for a given frame (frames counted from 0).
* @param mxf_path Pathname of MXF file to create.
* @param progress Signal to inform of progress.
* @param fps Frames per second.