Exiftool 9.85 reports mp4 files that has no video stream as video/mp4

[tim-kos]

Hey there,

I have an output file that was generated from an input.mp3 file (both files are here: http://static.transloadit.com/input_and_output.zip) like this:

Code Select Expand


ffmpeg -f mp3 -i input.mp3 -map 0 -map -0\:d -map -0\:s -map -0\:v -f mp4 -codec:a libfdk\_aac -b:a 128k -ar 44100 -afterburner 1 -ac 2 -vn output


Notice I use -vn to supress the video stream. ffmpeg, ffprobe, mp4box and mediainfo report, that output does not have a video stream. However, exiftool reports the file to have the video/mp4 mime type, but I expect it to be audio/m4a:

Code Select Expand


ExifTool Version Number         : 9.85
File Name                       : 2
Directory                       : .
File Size                       : 3.5 MB
File Modification Date/Time     : 2015:02:18 09:41:19+01:00
File Access Date/Time           : 2015:02:18 09:41:49+01:00
File Inode Change Date/Time     : 2015:02:18 09:41:19+01:00
File Permissions                : rw-r--r--
File Type                       : MP4
MIME Type                       : video/mp4
Major Brand                     : MP4  Base Media v1 [IS0 14496-12:2003]
Minor Version                   : 0.2.0
...


To be fair, the file cli tool also reports this:

Code Select Expand


$ file --mime-type -b output
video/mp4


is there any chance this can be fixed?

Thank you in advance for your help!
-Tim

[Phil Harvey]

Hi Tim,

I think this is a question better suited to an ffmpeg forum.  I looked at the file and the identifier is 'isom', but it should be 'M4A ' for an m4a file.  I don't really know the details of the differences between these two file types, but it is likely more than just the identifier.

- Phil