Fix channel count propagation on HLS traditional preparation

PiperOrigin-RevId: 235189983

library/core/src/main/java/com/google/android/exoplayer2/Format.java

@@ -1047,6 +1047,7 @@ public final class Format implements Parcelable {
       int bitrate,
       int width,
       int height,
+      int channelCount,
       @C.SelectionFlags int selectionFlags,
       @Nullable String language) {
     return new Format(

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java

@@ -1094,6 +1094,10 @@ import java.util.List;
       return sampleFormat;
     }
     int bitrate = propagateBitrate ? playlistFormat.bitrate : Format.NO_VALUE;
+    int channelCount =
+        playlistFormat.channelCount != Format.NO_VALUE
+            ? playlistFormat.channelCount
+            : sampleFormat.channelCount;
     int sampleTrackType = MimeTypes.getTrackType(sampleFormat.sampleMimeType);
     String codecs = Util.getCodecsOfType(playlistFormat.codecs, sampleTrackType);
     String mimeType = MimeTypes.getMediaMimeType(codecs);
@@ -1108,6 +1112,7 @@ import java.util.List;
         bitrate,
         playlistFormat.width,
         playlistFormat.height,
+        channelCount,
         playlistFormat.selectionFlags,
         playlistFormat.language);
   }