M4V support

[grdw]

Follow up from #138

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Currently in Spaceship we have a video thumbnailer. In Spaceship we check the file extension instead of actually using the format parser (mainly because changing the file extension on mobile is quite uncommon). However, we still have plans to use the format parser for this, if only it supported M4V formats.

Related: WeTransfer/spaceship#1975

[julik]

Isn't MV4 a subset of MPEG4 and thus effectively MOV? The parser we have should be picking it up.

[julik]

I.e. it should be supported via https://github.com/WeTransfer/format_parser/blob/master/lib/parsers/moov_parser.rb or it should be relatively within reach to make sure it is supported

[grdw]

Isn't MV4 a subset of MPEG4 and thus effectively MOV?

I didn't knew this, but I just learned that is the case indeed. It is like a MOV. I guess it requires some minor changes to the likely_match? method, to make sure the mov parser get's sorted on top of the list of parsers, but I guess that's it. It already should be supported indeed.