public static com.google.protobuf.Parser<AudioMapping> parser() {
      return PARSER;
    }
<pre>
Audio volume control in dB. Negative values decrease volume,
positive values increase. The default is 0.
</pre>

<code>double gain_db = 6;</code>

@return This builder for chaining.
java-video-transcoder/proto-google-cloud-video-transcoder-v1/src/main/java/com/google/cloud/video/transcoder/v1/AudioStream.java