TPESystem/Media/MediaSupportFileFormat

Media Supported File Format

Some tips/clues shown below can help you know why the newly-added file is not seen or cannot be played. For videos, usually if the thumbnail of a file cannot be generated, it cannot be shown in Gallery or Video APP. Related bugs: bug 942078
Some information in MDN: https://developer.mozilla.org/en-US/docs/How_Mozilla_determines_MIME_Types

1. File Type Check
   Files are categorized in 3 groups, pictures, music, and videos @http://dxr.mozilla.org/mozilla-central/source/toolkit/content/devicestorage.properties You need to check if your file extension is in the following list. Otherwise it will be not recognized as media files.
   • Pictures:
   *.jpe; *.jpg; *.jpeg; *.gif; *.png; *.bmp
   • Music:
   *.mp3; *.ogg; *.m4a; *.m4b; *.m4p; *.m4r; *.3gp; *.mp4; *.m3u; *.pls; *.opus; *.amr
   • Videos:
   *.mp4; *.mpeg; *.mpg; *.ogv; *.ogx; *.webm; *.3gp; *.ogg; *.m4v;
2. MIME Type Get
   For Gaia,
   Before getting metadata and thumbnail then, canPlayType is used to check if it is valid video file by passing MIME type to gecko to check.
   Gaia Code:
   http://mxr.mozilla.org/gaia/source/apps/video/js/metadata.js#162
   Gecko Code:
   http://mxr.mozilla.org/mozilla-central/source/content/html/content/src/HTMLMediaElement.cpp#2478 This MIME type is obtained from extension list extraMimeEntries @http://dxr.mozilla.org/mozilla-central/source/uriloader/exthandler/nsExternalHelperAppService.cpp#483
   So if your file extension is not in the list. You will get a empty MIME.
3. Sniff
   If you file passes those two checks explained above, it doesn't mean thumbnail can be generated or can be played successfully. Those checks only try to find a match in the mapping list of MIME and file extension.
   In Gecko, DataSource(frameworks/base/media/libstagefright/DataSource.cpp sniff()) will sniff the files and try to find the corresponding extractor. You can find how many and which formats supported in RegisterDefaultSniffers().
4. MIME mapper in Gaia
   There is a mime and file extension mapping list in Gaia(http://mxr.mozilla.org/gaia/source/shared/js/mime_mapper.js). Currently this is used for those media files not in storage, like mail attachment. It can be used to get file extension by passing MIME type.