[FFmpeg-devel] Adding support from some GoPro udta tags

[Jean Caillé]

Hello,

GoPro sets some specific udta tags in their videos. Two of 
those are the FIRM and HMMT udta tags.
The FIRM tag is a string containing the firmware version.
Tht MHHT tag contains a number of "Hero Moments" tags. Those moments are set by 
the user while recording and can be used to help finding interesting moments in 
a long video.

Proposed here are two patches for handling those udta tags. Note that
as discussed with Clément Boesch, individual HMMT tags are set as chapters
of the video.

Test footage : https://www.dropbox.com/s/zrx1nepiti5ajsj/GOPR8508.MP4

Test footage has firmware "HX1.01.02.00" and 4 Hero Moments, at around 5, 10, 
15 and 20 seconds.

As I am not yet a member of ffmpeg-devel, I would appreciate being cc'd 
in order to receive feedback for the two patches.

Thank you for your review,

-- 
Jean Caillé