Add support for voice changer

[StephenHodgson]

• https://elevenlabs.io/docs/api-reference/speech-to-speech/convert
• https://elevenlabs.io/docs/api-reference/speech-to-speech/convert-as-stream

[SAUFRAS0FT]

Hello everyone, this is my first public contribution.
I created my own class to call the VoiceChanger API via HTTP (not in streaming mode).
I didn't have time to do this properly, create my branch in the repo, and properly integrate it into the library because I had to do it quickly.
I'm still taking the time to share my code with you. It works well for me, and it requires the library to be installed, so it uses the structures you've already coded, such as VoiceSettings or the OutputFormat enumeration.

It could definitely help motivate someone to complete the project and integrate it into the library.
I hope I was able to help you!

using System.Net.Http.Headers;
using System.Text.Json;
using ElevenLabs.Voices;
using System.Text;

public class ElevenLabsClient
{
	private readonly HttpClient _http;
	private const string BaseUrl = "https://api.elevenlabs.io/v1";

	public ElevenLabsClient(string apiKey) {
		_http = new HttpClient();
		_http.DefaultRequestHeaders.Add("xi-api-key", apiKey);
	}

	public async Task<byte[]> ChangeVoiceAsync(string voiceId, byte[] wavAudio, string modelId = "eleven_english_sts_v2", int? seed = null, bool removeBackgroundNoise = false, VoiceSettings? voiceSettings = null, ElevenLabs.OutputFormat? fileFormat = null, bool enableLogging = false ) {
		var url = $"{BaseUrl}/speech-to-speech/{voiceId}";
		if (!enableLogging)
			url += "?enable_logging=false";

		using var content = new MultipartFormDataContent();

		// audio
		var audioContent = new ByteArrayContent(wavAudio);
		audioContent.Headers.ContentType = new MediaTypeHeaderValue("audio/wav");
		content.Add(audioContent, "audio", "input.wav");

		// model_id
		content.Add(new StringContent(modelId), "model_id");

		// optional: seed
		if (seed.HasValue)
			content.Add(new StringContent(seed.Value.ToString()), "seed");

		// remove_background_noise
		content.Add(new StringContent(removeBackgroundNoise ? "true" : "false"), "remove_background_noise");

		// voice_settings as JSON string
		if (voiceSettings is not null) {
			var voiceSettingsJson = JsonSerializer.Serialize(voiceSettings);
			content.Add(new StringContent(voiceSettingsJson, Encoding.UTF8, "application/json"), "voice_settings");
		}

		// output_format
		if (fileFormat is not null)
			content.Add(new StringContent(fileFormat.ToString()), "output_format");

		// POST
		using var response = await _http.PostAsync(url, content);
		
		if (response.IsSuccessStatusCode) {
			return await response.Content.ReadAsByteArrayAsync();
		} else {
			string message = await response.Content.ReadAsStringAsync();
			throw new Exception($"ElevenLabs API return HTTP {response.StatusCode} with message \"{message}\"");
		}
			
	}

}

[StephenHodgson]

You can always make a fork and open a pull request :) If not I'll eventually add this in. Thanks!

[SAUFRAS0FT]

Thanks for editing the markdown that I couldn't fix!

I'll try to do it properly this weekend, especially since I also made the Create Transcript call.

Give me time to analyze how your library is built so I don't mess up (I've never used it, just installed it for enumerations and data classes...). I'll try to do that this weekend. This is the first time I'm going to contribute to a project on github so I'm pretty excited and I hope to do things right.