Add support for extracting 32-bit float WAVE

Issue: google#3379

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=179925320

RELEASENOTES.md

@@ -23,6 +23,8 @@
 * Audio:
   * Support 32-bit PCM float output from `DefaultAudioSink`, and add an option
     to use this with `FfmpegAudioRenderer`.
+  * Add support for extracting 32-bit WAVE files
+    ([#3379](https://github.com/google/ExoPlayer/issues/3379)).
   * Support extraction and decoding of Dolby Atmos
     ([#2465](https://github.com/google/ExoPlayer/issues/2465)).
   * Fix handling of playback parameter changes while paused when followed by a

library/core/src/main/java/com/google/android/exoplayer2/extractor/wav/WavHeaderReader.java

@@ -31,6 +31,8 @@
 
   /** Integer PCM audio data. */
   private static final int TYPE_PCM = 0x0001;
+  /** Float PCM audio data. */
+  private static final int TYPE_FLOAT = 0x0003;
   /** Extended WAVE format. */
   private static final int TYPE_WAVE_FORMAT_EXTENSIBLE = 0xFFFE;
 
@@ -87,14 +89,22 @@ public static WavHeader peek(ExtractorInput input) throws IOException, Interrupt
           + blockAlignment);
     }
 
-    @C.PcmEncoding int encoding = Util.getPcmEncoding(bitsPerSample);
-    if (encoding == C.ENCODING_INVALID) {
-      Log.e(TAG, "Unsupported WAV bit depth: " + bitsPerSample);
-      return null;
+    @C.PcmEncoding int encoding;
+    switch (type) {
+      case TYPE_PCM:
+      case TYPE_WAVE_FORMAT_EXTENSIBLE:
+        encoding = Util.getPcmEncoding(bitsPerSample);
+        break;
+      case TYPE_FLOAT:
+        encoding = bitsPerSample == 32 ? C.ENCODING_PCM_FLOAT : C.ENCODING_INVALID;
+        break;
+      default:
+        Log.e(TAG, "Unsupported WAV format type: " + type);
+        return null;
     }
 
-    if (type != TYPE_PCM && type != TYPE_WAVE_FORMAT_EXTENSIBLE) {
-      Log.e(TAG, "Unsupported WAV format type: " + type);
+    if (encoding == C.ENCODING_INVALID) {
+      Log.e(TAG, "Unsupported WAV bit depth " + bitsPerSample + " for type " + type);
       return null;
     }