Speech-to-Text for .NET using Whisper, powered by AI/ML API. Transcribe audio files, generate subtitles (SRT/VTT), detect languages, and get word-level timestamps. Supports MP3, WAV, M4A, WebM, and more. Perfect for meeting transcription, podcast subtitles, voice notes, and accessibility features.
Get Started
$ dotnet add package ForeverTools.STTReadme
ForeverTools.STT
Speech-to-Text for .NET using Whisper, powered by AI/ML API. Transcribe audio files, generate subtitles, detect languages, and get word-level timestamps.
Features
- Whisper Models: Access OpenAI Whisper and Whisper Large V3
- Multiple Input Sources: Files, bytes, streams, or URLs
- Subtitle Generation: Export to SRT or VTT format
- Language Detection: Auto-detect or specify source language
- Timestamps: Get segment and word-level timing
- Batch Processing: Transcribe multiple files
- Easy Integration: Simple API with dependency injection support
Getting Your API Key
This package uses the AI/ML API which provides access to Whisper and 400+ AI models.
- Sign up at aimlapi.com
- Get your API key from the dashboard
- Start transcribing!
Installation
dotnet add package ForeverTools.STT
Quick Start
Basic Transcription
using ForeverTools.STT;
// Create client with your API key
var client = new SpeechToTextClient("your-api-key");
// Transcribe an audio file
var text = await client.TranscribeAsync("meeting.mp3");
Console.WriteLine(text);
Using Environment Variables
// Set AIML_API_KEY or STT_API_KEY environment variable
var client = SpeechToTextClient.FromEnvironment();
Transcription Examples
From File
// Simple - just get the text
var text = await client.TranscribeAsync("podcast.mp3");
// Detailed - get timestamps and metadata
var result = await client.TranscribeWithDetailsAsync("podcast.mp3");
Console.WriteLine($"Text: {result.Text}");
Console.WriteLine($"Language: {result.Language}");
Console.WriteLine($"Duration: {result.Duration}");
foreach (var segment in result.Segments)
{
Console.WriteLine($"[{segment.Start:mm\\:ss} - {segment.End:mm\\:ss}] {segment.Text}");
}
From Bytes or Stream
// From bytes
byte[] audioData = File.ReadAllBytes("audio.mp3");
var text = await client.TranscribeAsync(audioData, "audio.mp3");
// From stream
using var stream = File.OpenRead("audio.mp3");
var text = await client.TranscribeAsync(stream, "audio.mp3");
From URL
// Transcribe audio from a URL
var text = await client.TranscribeFromUrlAsync("https://example.com/podcast.mp3");
Subtitle Generation
Generate SRT Subtitles
// Get SRT format directly
var srt = await client.TranscribeToSrtAsync("video.mp3");
File.WriteAllText("video.srt", srt);
// Output:
// 1
// 00:00:00,000 --> 00:00:05,230
// Welcome to the podcast.
//
// 2
// 00:00:05,230 --> 00:00:10,500
// Today we'll be discussing...
Generate VTT Subtitles
// Get WebVTT format
var vtt = await client.TranscribeToVttAsync("video.mp3");
File.WriteAllText("video.vtt", vtt);
// Output:
// WEBVTT
//
// 00:00:00.000 --> 00:00:05.230
// Welcome to the podcast.
//
// 00:00:05.230 --> 00:00:10.500
// Today we'll be discussing...
Convert Existing Segments
var result = await client.TranscribeWithDetailsAsync("audio.mp3");
// Generate subtitles from segments
var srt = SpeechToTextClient.GenerateSrt(result.Segments);
var vtt = SpeechToTextClient.GenerateVtt(result.Segments);
Language Options
Auto-Detect Language
// Language is auto-detected by default
var result = await client.TranscribeWithDetailsAsync("audio.mp3");
Console.WriteLine($"Detected language: {result.Language}");
Specify Language
var result = await client.TranscribeWithDetailsAsync(new TranscriptionRequest
{
FilePath = "audio.mp3",
Language = TranscriptionLanguages.Spanish
});
Detect Language Only
var detection = await client.DetectLanguageAsync("audio.mp3");
Console.WriteLine($"Language: {detection.LanguageName} ({detection.LanguageCode})");
Advanced Options
Full Request Configuration
var result = await client.TranscribeWithDetailsAsync(new TranscriptionRequest
{
FilePath = "meeting.mp3",
Model = SttModels.WhisperLargeV3, // Use larger model for accuracy
Language = TranscriptionLanguages.English,
Temperature = 0.2f, // Lower = more deterministic
Prompt = "Meeting about Q4 financials", // Guide vocabulary
ResponseFormat = ResponseFormats.VerboseJson
});
Different Models
// Fast model (default)
var options = new SpeechToTextOptions
{
ApiKey = "your-api-key",
DefaultModel = SttModels.Whisper1
};
// High accuracy model
var options = new SpeechToTextOptions
{
ApiKey = "your-api-key",
DefaultModel = SttModels.WhisperLargeV3
};
var client = new SpeechToTextClient(options);
Batch Transcription
var files = new[] { "meeting1.mp3", "meeting2.mp3", "meeting3.mp3" };
var results = await client.TranscribeBatchAsync(files);
foreach (var result in results)
{
Console.WriteLine($"Duration: {result.Duration}, Text: {result.Text.Substring(0, 100)}...");
}
Dependency Injection
ASP.NET Core
// In Program.cs
builder.Services.AddForeverToolsSTT("your-api-key");
// Or with configuration
builder.Services.AddForeverToolsSTT(options =>
{
options.ApiKey = "your-api-key";
options.DefaultModel = SttModels.WhisperLargeV3;
options.DefaultLanguage = "en";
});
From Configuration
// appsettings.json
{
"SpeechToText": {
"ApiKey": "your-api-key",
"DefaultModel": "whisper-1",
"DefaultLanguage": "en",
"Temperature": 0
}
}
builder.Services.AddForeverToolsSTT(builder.Configuration);
Using in Services
public class TranscriptionService
{
private readonly SpeechToTextClient _stt;
public TranscriptionService(SpeechToTextClient stt)
{
_stt = stt;
}
public async Task<string> TranscribeMeetingAsync(string filePath)
{
return await _stt.TranscribeAsync(filePath);
}
}
Supported Audio Formats
| Format | Extension | MIME Type |
|---|---|---|
| MP3 | .mp3 | audio/mpeg |
| WAV | .wav | audio/wav |
| M4A | .m4a | audio/mp4 |
| WebM | .webm | audio/webm |
| FLAC | .flac | audio/flac |
| OGG | .ogg | audio/ogg |
| MP4 | .mp4 | audio/mp4 |
Available Models
| Model | Best For | Speed | Accuracy |
|---|---|---|---|
whisper-1 | General use | Fast | Good |
whisper-large-v3 | High accuracy | Slower | Excellent |
whisper-large-v3-turbo | Balanced | Medium | Very Good |
Error Handling
try
{
var text = await client.TranscribeAsync("audio.mp3");
}
catch (FileNotFoundException ex)
{
Console.WriteLine($"File not found: {ex.FileName}");
}
catch (ArgumentException ex)
{
Console.WriteLine($"Invalid input: {ex.Message}");
}
catch (HttpRequestException ex)
{
Console.WriteLine($"API error: {ex.Message}");
}
Best Practices
- Choose the right model: Use
whisper-1for speed,whisper-large-v3for accuracy - Specify language: If you know the language, specify it for better results
- Use prompts: For domain-specific vocabulary, provide context via prompt
- Handle large files: For files over 25MB, consider splitting audio
- Reuse the client: Create one
SpeechToTextClientand reuse it
Other ForeverTools Packages
| Package | Description | NuGet |
|---|---|---|
| ForeverTools.AIML | Access 400+ AI models (GPT-4, Claude, Llama, Gemini, DALL-E) |  |
| ForeverTools.Translate | AI-powered translation with 100+ languages |  |
| ForeverTools.OCR | AI-powered OCR using GPT-4 Vision, Claude 3, and Gemini |  |
| ForeverTools.ImageGen | AI image generation with social media presets (DALL-E, Flux, SD) |  |
| ForeverTools.Proxy | Premium proxy rotation with BrightData (Residential, ISP, Mobile) |  |
| ForeverTools.ScraperAPI | Web scraping with proxy rotation and CAPTCHA bypass |  |
Support
License
MIT License - see LICENSE file for details.