Transcoding at lower bitrate for limited bandwidth (#58)

Hello!

To begin with, thanks a lot for Funkwhale and the Android application, which is delightful to use every day.

As mentioned in #58, the application does not yet have a way to reduce the amount of data exchanged between the player and the server. When streaming high-quality audio on 4G or 5G connection, it can get very costly if one does consume a lot of FLAC content. This PR is an attempt at solving this issue and is my first contribution to the project. I would appreciate some hints/helps according to unit tests, translations, and probably things I did not cover for the moment...

Here is a summary of what I have done:

• Add a new setting called "Bandwidth limitation" with an icon, and a basic description,
• If bandwidth limitation is set to limited, append &to=mp3&max_bitrate=320 to the listen URL of the candidate best track upload.

A better way to do it in the future would be to add a bar to configure the desired maximum bitrate, and probably check in the cache if the best upload is already there before asking for a reduced one. Testing that the best quality upload is already meeting the bandwidth constraint would be interesting to avoid an unneeded transcoding on the server side. I prefer to point out the flaws so that we can discuss about them together! 😄

Thank in advance,

Dylan

app/src/main/java/audio/funkwhale/ffa/playback/PlayerService.kt

@@ -33,6 +33,7 @@ import audio.funkwhale.ffa.utils.maybeNormalizeUrl
 import audio.funkwhale.ffa.utils.onApi
 import com.google.android.exoplayer2.C
 import com.google.android.exoplayer2.ExoPlayer
+import com.google.android.exoplayer2.IllegalSeekPositionException
 import com.google.android.exoplayer2.PlaybackException
 import com.google.android.exoplayer2.Player
 import com.google.android.exoplayer2.Tracks
@@ -154,12 +155,17 @@ class PlayerService : Service() {
       player.setMediaSource(queue.dataSources)
       player.prepare()
 
-      FFACache.getLine(this, "progress")?.let {
-        player.seekTo(queue.current, it.toLong())
 
-        val (current, duration, percent) = getProgress(true)
 
-        ProgressBus.send(current, duration, percent)
+      FFACache.getLine(this, "progress")?.let {
+        try {
+          player.seekTo(queue.current, it.toLong())
+          val (current, duration, percent) = getProgress(true)
+          ProgressBus.send(current, duration, percent)
+        } catch (e: IllegalSeekPositionException) {
+          // The app remembered an incorrect position, let's reset it
+          FFACache.set(this, "current", "-1")
+        }
       }
     }