Incorrect GIF format detection if extension was omitted?

[mooyoul]

Hello, I've found some GIF files were detected as non-GIF format.

Please see this screenshot:

Left: Results from FFprobe / Right: Results from MediaInfo

As you see, Detected formats are non-GIF format or missing even these files have valid GIF89a files and has GIF file signature with 89a extension (GIF89a signature).

Please see left panel on this screenshot:

Interesting part is: GIF analysis works if i add .gif extension to files. Please see right panel of this screenshot:

You can download sample files on below links:

• https://s3.amazonaws.com/test-mooyoul/public/mediainfolib-samples/hijl325b9s06xggrhsd9
• https://s3.amazonaws.com/test-mooyoul/public/mediainfolib-samples/kwdu1fwympyuksxmqjic
• https://s3.amazonaws.com/test-mooyoul/public/mediainfolib-samples/t3ugtcnyndfei40jn7hd
• https://s3.amazonaws.com/test-mooyoul/public/mediainfolib-samples/uedhjaijuljgmug6opej

Is it intended result? what's different if filename has extension, or not?

[JeromeMartinez]

Not intended. When the extension is .gif, the GIF parser is prioritized, and it catches the file; when no extension is provided, all parsers are tested, and here some parsers (not GIF) consider it is their formats, due to not enough precise detection. Definitely a bug.

[mooyoul]

Ah okay, Is there any way to prioritize specific parser without modifying original filename? I've tried with mediainfo --File_FileName=some-image.gif mediainfolib-samples/hijl325b9s06xggrhsd9 but there's no luck.

[JeromeMartinez]

Hidden option (definitely lack of doc :( ) mediainfo --File_ForceParser=GIF

[mooyoul]

woo, works like a charm. In the meantime i'll just peek given file to detect GIF signature and pass force parser option to mediainfo if given file was detected as GIF. Merci, @JeromeMartinez!