//define a fileInputStream object to read the subtitle input file, in this example a TTML one
FileInputStream fileInputStream = new FileInputStream();
fileInputStream.setFileType(FileInputStreamType.TTML); //allowed values are TTML, SRT and WEBVTT
fileInputStream.setInputId(s3Input.getId());
fileInputStream.setInputPath("sampleTTML.xml");
fileInputStream = bitmovinApi.encoding.encodings.inputStreams.file.create(encoding.getId(), fileInputStream);

//define a WebVTT configuration
WebVttConfiguration webVttConfiguration = new WebVttConfiguration();
webVttConfiguration.setName("WebVTT_sample");
webVttConfiguration = bitmovinApi.encoding.configurations.subtitles.webvtt.create(webVttConfiguration);

//create a Stream object to apply the conversion
Stream stream = new Stream();
stream.setCodecConfigId(webVttConfiguration.getId()); //applies WebVTT configuration
StreamInput stream_streamInput = new StreamInput();
stream_streamInput.setInputStreamId(fileInputStream.getId()); //takes subtitle TTML input file
stream_streamInput.setSelectionMode(StreamSelectionMode.AUTO);
stream.setInputStreams(List.of(stream_streamInput));
stream = bitmovinApi.encoding.encodings.streams.create(encoding.getId(), stream);

//mux the WebVTT subtitles writing them to .vtt file in your desired output
TextMuxing textMuxing = new TextMuxing();
textMuxing.setFilename("subtitle.vtt");
EncodingOutput textMuxing_encodingOutput = new EncodingOutput();
AclEntry textMuxing_encodingOutput_aclEntry = new AclEntry();
textMuxing_encodingOutput_aclEntry.setPermission(AclPermission.PUBLIC_READ); //or PRIVATE
textMuxing_encodingOutput.setAcl(List.of(textMuxing_encodingOutput_aclEntry));
textMuxing_encodingOutput.setOutputId(s3Output.getId());
textMuxing_encodingOutput.setOutputPath("yourOutputPath/subtitles/webvtt/");
textMuxing.setOutputs(List.of(textMuxing_encodingOutput));
textMuxing.setStreamConditionsMode(StreamConditionsMode.DROP_MUXING);
MuxingStream textMuxing_muxingStream = new MuxingStream();
textMuxing_muxingStream.setStreamId(stream.getId());
textMuxing.setStreams(List.of(textMuxing_muxingStream));
textMuxing = bitmovinApi.encoding.encodings.muxings.text.create(encoding.getId(), textMuxing);