[FFmpeg-trac] #4209(avformat:open): GPS coordinates location and other iOS metadata in MOV are not copied to output MP4

[FFmpeg]

#4209: GPS coordinates location and other iOS metadata in MOV are not copied to
output MP4
------------------------------------+------------------------------------
             Reporter:  elmimmo     |                    Owner:
                 Type:  defect      |                   Status:  open
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:  mov         |               Blocked By:
             Blocking:              |  Reproduced by developer:  1
Analyzed by developer:  0           |
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Comment (by kvasa):

 This seems to be the issue - when you load the input and output files
 using `AVFoundation` (as `AVAsset`) and read the metadata, here is the
 difference:

 Input:

 {{{
    [...]
     <AVMetadataItem: 0x7fb602ef1ce0,
 identifier=mdta/com.apple.quicktime.location.ISO6709, keySpace=mdta, key
 class = __NSCFString, key=com.apple.quicktime.location.ISO6709,
 commonKey=location, extendedLanguageTag=(null),
 dataType=com.apple.metadata.datatype.UTF-8, time={INVALID},
 duration={INVALID}, startDate=(null), extras={
     dataType = 1;
     dataTypeNamespace = "com.apple.quicktime.mdta";
 }, value class=__NSCFString, value=+XX.6405-YY.8118+371.450/>
    [...]
 }}}

 Output file:

 {{{
    [...]
    <AVMetadataItem: 0x7ff2d5217a50, identifier=itsk/%00%00%00%05,
 keySpace=itsk, key class = __NSCFNumber, key=, commonKey=(null),
 extendedLanguageTag=(null), dataType=com.apple.metadata.datatype.UTF-8,
 time={INVALID}, duration={INVALID}, startDate=(null), extras={
     dataType = 1;
     dataTypeNamespace = "com.apple.itunes";
 }, value class=__NSCFString, value=+XX.6405-YY.8118+371.450/>
    [...]
 }}}

 Key differences:

 - identifier is set to `itsk/%00%00%00%05` (as it's the fifth metadata
 item), instead of copying the input identifier
 `mdta/com.apple.quicktime.location.ISO6709`
 - namespace is set to `com.apple.itunes` instead of
 `com.apple.quicktime.mdta`

 It is very likely that Apple requires the metadata items to be in the
 correct namespace, with the right identifier. I am not sure what is the
 exact issue as searching through FFmpeg source code, I can't find `itsk`
 or `com.apple.itunes`, so I am assuming that these get generated by
 `AVFoundation` if the correct value cannot be read...

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4209#comment:22>
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