Revert to using header bitrate for CBR MP3s

A previous change switched to calculation of the bitrate based on the first MPEG audio header in the stream. This had the effect of fixing seeking to be consistent with playing from the start for streams where every frame has the same padding value, but broke streams where the encoder (correctly) modifies the padding value to match the declared bitrate in the header. Issue: google#6238 PiperOrigin-RevId: 261163904
qiqian · Aug 2, 2019 · 80bc50b · 80bc50b
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Showing 6 changed files with 9 additions and 11 deletions.
diff --git a/RELEASENOTES.md b/RELEASENOTES.md
@@ -9,8 +9,12 @@
   tags instead of 3-letter ISO 639-2 language tags.
 * Ensure the `SilenceMediaSource` position is in range
   ([#6229](https://github.com/google/ExoPlayer/issues/6229)).
-* Calculate correct duration for clipped WAV streams
+* WAV: Calculate correct duration for clipped streams
   ([#6241](https://github.com/google/ExoPlayer/issues/6241)).
+* MP3: Use CBR header bitrate, not calculated bitrate. This reverts a change
+  from 2.9.3 ([#6238](https://github.com/google/ExoPlayer/issues/6238)).
+* Flac extension: Parse `VORBIS_COMMENT` and `PICTURE` metadata
+  ([#5527](https://github.com/google/ExoPlayer/issues/5527)).
 * Fix issue where initial seek positions get ignored when playing a preroll ad
   ([#6201](https://github.com/google/ExoPlayer/issues/6201)).
 * Fix issue where invalid language tags were normalized to "und" instead of
@@ -20,8 +24,6 @@
   ([#6192](https://github.com/google/ExoPlayer/issues/6192)).
 * Fix Flac and ALAC playback on some LG devices
   ([#5938](https://github.com/google/ExoPlayer/issues/5938)).
-* Flac extension: Parse `VORBIS_COMMENT` and `PICTURE` metadata
-  ([#5527](https://github.com/google/ExoPlayer/issues/5527)).
 
 ### 2.10.3 ###
 

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/MpegAudioHeader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/MpegAudioHeader.java
@@ -186,10 +186,6 @@ public static boolean populateHeader(int headerData, MpegAudioHeader header) {
       }
     }
 
-    // Calculate the bitrate in the same way Mp3Extractor calculates sample timestamps so that
-    // seeking to a given timestamp and playing from the start up to that timestamp give the same
-    // results for CBR streams. See also [internal: b/120390268].
-    bitrate = 8 * frameSize * sampleRate / samplesPerFrame;
     String mimeType = MIME_TYPE_BY_LAYER[3 - layer];
     int channels = ((headerData >> 6) & 3) == 3 ? 1 : 2;
     header.setValues(version, mimeType, frameSize, sampleRate, channels, bitrate, samplesPerFrame);

diff --git a/library/core/src/test/assets/mp3/play-trimmed.mp3.0.dump b/library/core/src/test/assets/mp3/play-trimmed.mp3.0.dump
@@ -1,6 +1,6 @@
 seekMap:
   isSeekable = true
-  duration = 26122
+  duration = 26125
   getPosition(0) = [[timeUs=0, position=0]]
 numberOfTracks = 1
 track 0:

diff --git a/library/core/src/test/assets/mp3/play-trimmed.mp3.1.dump b/library/core/src/test/assets/mp3/play-trimmed.mp3.1.dump
@@ -1,6 +1,6 @@
 seekMap:
   isSeekable = true
-  duration = 26122
+  duration = 26125
   getPosition(0) = [[timeUs=0, position=0]]
 numberOfTracks = 1
 track 0:

diff --git a/library/core/src/test/assets/mp3/play-trimmed.mp3.2.dump b/library/core/src/test/assets/mp3/play-trimmed.mp3.2.dump
@@ -1,6 +1,6 @@
 seekMap:
   isSeekable = true
-  duration = 26122
+  duration = 26125
   getPosition(0) = [[timeUs=0, position=0]]
 numberOfTracks = 1
 track 0:

diff --git a/library/core/src/test/assets/mp3/play-trimmed.mp3.3.dump b/library/core/src/test/assets/mp3/play-trimmed.mp3.3.dump
@@ -1,6 +1,6 @@
 seekMap:
   isSeekable = true
-  duration = 26122
+  duration = 26125
   getPosition(0) = [[timeUs=0, position=0]]
 numberOfTracks = 1
 track 0: