public Builder clearRateControlMode() {
        rateControlMode_ = getDefaultInstance().getRateControlMode();
        bitField0_ = (bitField0_ & ~0x00000020);
        onChanged();
        return this;
      }
<pre>
Specify the `rate_control_mode`. The default is `vbr`.

Supported rate control modes:

- `vbr` - variable bitrate
- `crf` - constant rate factor
</pre>

<code>string rate_control_mode = 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/VideoStream.java