add comment for mBitRate in audio decoder

diff --git a/libstagefright/codecs/ffmpegdec/adec/SoftFFmpegAudio.h b/libstagefright/codecs/ffmpegdec/adec/SoftFFmpegAudio.h
index 6abc1cc..7aec5a4 100644 (file)
--- a/libstagefright/codecs/ffmpegdec/adec/SoftFFmpegAudio.h
+++ b/libstagefright/codecs/ffmpegdec/adec/SoftFFmpegAudio.h
@@ -125,7 +125,8 @@ private:
 
     int32_t mNumChannels;
     int32_t mSamplingRate;
-    int32_t mBitRate;  // some audio codec need bit rate when init
+    /* some audio codec need bit rate when init, e.g. wma, and should be > 0 */
+    int32_t mBitRate;
     AVSampleFormat mSamplingFmt;
     bool mAudioConfigChanged;