On 2/24/2016 3:19 PM, Carl Eugen Hoyos wrote: > (Do you have an example where the probing fails?) > > The idea of these additional demuxers is that they probe > the content instead of relying on the file suffix. > File suffix provides a score of _EXTENSION (50), so if probing > is possible and uses more than 16 bit, _EXTENSION + 1 is > returned to allow a better detection. > AV_SCORE_MIME is 75, so iiuc this patch would just disable > autodetection (except for png, dds and webp which compare > 64 bit and return _MAX) in favour of the mimetype. > Or am I reading the code incorrectly and mimetype doesn't > lead to a score of 75? > > Why aren't the mimetypes added to the (original) image2 > demuxer if they are really needed?
From the author: First I'll address the image2 suggestion. It certainly is possible to put a large list of image MIME types in the image2 demuxer, however, a MIME type is associated with a specific image format, so it is a waste of information not to use it to detect the specific format when appropriate. The primary purpose of image2 is for image sequences, so using MIME types for that is not applicable at all. Just because image2 calls the other probe functions internally to select the codec doesn't mean that the other image formats shouldn't be first-class citizens in terms of detection. In terms of how the score for a MIME type match compares with those of the individual content matching probe functions, I'd say it makes sense. The stronger probing functions have a score which reflects their reliability. If a MIME type is specified, that does have significant weight in terms of probability, given that it was set somewhere either by a client or server program doing a content check or explicitly by some user. So maybe it should override the weaker content checks. It is similar to extension, but it is less likely to be arbitrary if present and matching a specific media format. - Derek _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
