AtomicParsley 3gp help page for setting 3GPP-style metadata.
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  3GPP text tags can be encoded in either UTF-8 (default input encoding) or UTF-16 (converted from UTF-8)
  Many 3GPP text tags can be set for a desired language by a 3-letter-lowercase code (default is "eng").
  For tags that support the language attribute (all except year), more than one tag of the same name
  (3 titles for example) differing in the language code is supported.

  iTunes-style metadata is not supported by the 3GPP TS 26.244 version 6.4.0 Release 6 specification.
  3GPP asset tags can be set at movie level or track level & are set in a different hierarchy: moov.udta 
  if at movie level (versus iTunes moov.udta.meta.ilst). Other 3rd party utilities may allow setting
  iTunes-style metadata in 3gp files. When a 3gp file is detected (file extension doesn't matter), only
  3gp spec-compliant metadata will be read & written.

  Note1: there are a number of different 'brands' that 3GPP files come marked as. Some will not be 
         supported by AtomicParsley due simply to them being unknown and untested. You can compile your
         own AtomicParsley to evaluate it by adding the hex code into the source of APar_IdentifyBrand.

  Note2: There are slight accuracy discrepancies in location's fixed point decimals set and retrieved.

  Note3: QuickTime Player can see a limited subset of these tags, but only in 1 language & there seems to
         be an issue with not all unicode text displaying properly. This is an issue withing QuickTime -
         the exact same text (in utf8) displays properly in an MPEG-4 file. Some languages can also display
         more glyphs than others.

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 Tag setting options (default user data area is movie level; default lang is 'eng'; default encoding is UTF8):
     required arguments are in (parentheses); optional arguments are in [brackets]

  --3gp-title           (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp media title tag
  --3gp-author          (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp author of the media tag
  --3gp-performer       (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp performer or artist tag
  --3gp-genre           (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp genre asset tag
  --3gp-description     (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp description or caption tag
  --3gp-copyright       (str)  [lang=3str]  [UTF16]  [area]  .........  Set a 3gp copyright notice tag*

  --3gp-album           (str)  [lang=3str]  [UTF16]  [trknum=int] [area]  Set a 3gp album tag (& opt. tracknum)
  --3gp-year            (int)  [area]  ...........................  Set a 3gp recording year tag (4 digit only)

  --3gp-rating          (str)  [entity=4str]  [criteria=4str]  [lang=3str]  [UTF16]  [area]   Rating tag
  --3gp-classification  (str)  [entity=4str]  [index=int]      [lang=3str]  [UTF16]  [area]   Classification

  --3gp-keyword         (str)   [lang=3str]  [UTF16]  [area]   Format of str: 'keywords=word1,word2,word3,word4'

  --3gp-location        (str)   [lang=3str]  [UTF16]  [area]   Set a 3gp location tag (default: Central Park)
                                 [longitude=fxd.pt]  [latitude=fxd.pt]  [altitude=fxd.pt]
                                 [role=str]  [body=str]  [notes=str]
                                 fxd.pt values are decimal coordinates (55.01209, 179.25W, 63)
                                 'role=' values: 'shooting location', 'real location', 'fictional location'
                                         a negative value in coordinates will be seen as a cli flag
                                         append 'S', 'W' or 'B': lat=55S, long=90.23W, alt=90.25B

 [area] can be "movie", "track" or "track=num" where 'num' is the number of the track. If not specificied,
 assets will be placed at movie level. The "track" option sets the asset across all available tracks

Note1: '4str' = a 4 letter string like "PG13"; 3str is a 3 letter string like "eng"; int is an integer
Note2: List all languages for '3str' with "AtomicParsley --language-list (unknown languages become "und")
*Note3: The 3gp copyright asset can potentially be altered by using the --ISO-copyright setting.
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Usage: AtomicParsley [3gpFILE] --option [argument] [optional_arguments]  [ --option2 [argument2]...] 

example: AtomicParsley /path/to.3gp -t 
example: AtomicParsley /path/to.3gp -T 1 
example: Atomicparsley /path/to.3gp --3gp-performer "Enjoy Yourself" lang=pol UTF16
example: Atomicparsley /path/to.3gp --3gp-year 2006 --3gp-album "White Label" track=8 lang=fra
example: Atomicparsley /path/to.3gp --3gp-album "Cow Cod Soup For Everyone" track=10 lang=car

example: Atomicparsley /path/to.3gp --3gp-classification "Poor Sport" entity="PTA " index=12 UTF16
example: Atomicparsley /path/to.3gp --3gp-keyword keywords="foo1,foo2,foo 3" UTF16 --3gp-keyword ""
example: Atomicparsley /path/to.3gp --3gp-location 'Bethesda Terrace' latitude=40.77 longitude=73.98W 
                                                    altitude=4.3B role='real' body=Earth notes='Underground'

example: Atomicparsley /path/to.3gp --3gp-title "I see London." --3gp-title "Veo Madrid." lang=spa 
                                    --3gp-title "Widze Warsawa." lang=pol


