The top-level message sent by the client for the
StreamingAnnotateVideo method. Multiple
StreamingAnnotateVideoRequest messages are sent. The first
message must only contain a StreamingVideoConfig message. All
subsequent messages must only contain input_content data.
bytes
The video data to be annotated. Chunks of video data are
sequentially sent in ``StreamingAnnotateVideoRequest``
messages. Except the initial
``StreamingAnnotateVideoRequest`` message containing only
``video_config``, all subsequent
``AnnotateStreamingVideoRequest`` messages must only contain
``input_content`` field. Note: as with all bytes fields,
protobuffers use a pure binary representation (not base64).