public com.google.protobuf.Duration.Builder getStartTimeBuilder() {
      bitField0_ |= 0x00000001;
      onChanged();
      return getStartTimeFieldBuilder().getBuilder();
    }
<pre>
Time offset relative to the beginning of the audio, and
corresponding to the start of the spoken word. This field is only set if
`enable_word_time_offsets=true` and only in the top hypothesis. This is an
experimental feature and the accuracy of the time offset can vary.
</pre>

<code>.google.protobuf.Duration start_time = 1;</code>
java-video-intelligence/proto-google-cloud-video-intelligence-v1p3beta1/src/main/java/com/google/cloud/videointelligence/v1p3beta1/WordInfo.java