Metadata pertaining to this request.
Optional AudioOptional Content Specifies the type audio stream. This should reflect the
OutputFormat parameter in your request.
If you request mp3 as the
OutputFormat, the ContentType returned is
audio/mpeg.
If you request ogg_vorbis as the
OutputFormat, the ContentType returned is
audio/ogg.
If you request pcm as the
OutputFormat, the ContentType returned is
audio/pcm in a signed 16-bit, 1 channel (mono), little-endian format.
If you request json as the
OutputFormat, the ContentType returned is
application/x-json-stream.
Optional RequestNumber of characters synthesized.
The output of SynthesizeSpeechCommand.