Fix #195: changelog

changes/changelog.d/195.feature

+Store file length, size and bitrate (#195)
+
+
+Storage of bitrate, size and length in database
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Starting with this release, when importing files, Funkwhale will store
+additional information about audio files:
+
+- Bitrate
+- Size (in bytes)
+- Duration
+
+This change is not retroactive, meaning already imported files will lack those
+informations. The interface and API should work as before in such case, however,
+we offer a command to deal with legacy files and populate the missing values.
+
+On docker setups:
+
+.. code-block:: shell
+
+    docker-compose run --rm api python manage.py fix_track_files
+
+
+On non-docker setups:
+
+.. code-block:: shell
+
+    # from your activated virtualenv
+    python manage.py fix_track_files
+
+.. note::
+
+    The execution time for this command is proportional to the number of
+    audio files stored on your instance. This is because we need to read the
+    files from disk to fetch the data. You can run it in the background
+    while Funkwhale is up.
+
+    It's also safe to interrupt this command and rerun it at a later point, or run
+    it multiple times.
+
+    Use the --dry-run flag to check how many files would be impacted.