Text to speech on Windows: the built-in voices, edge-tts, and why subtitle dubbing never fits

A developer compared text-to-speech options on Windows, showing that the built-in System.Speech API can synthesize speech to WAV files without installation or network access, while the edge-tts Python package drives Microsoft's neural Edge voices to produce MP3 output with matching subtitles. The writeup notes that voices installed through Windows Settings often fail to appear in System.Speech because SAPI 5 and OneCore voices live in separate registry hives, and that subtitle timings rarely accommodate synthesized narration, which typically overruns cue durations.

Narration for a video, a spoken prompt in an app, a subtitle file turned into audio: all of it starts with getting text read out and saved to a file. Windows can do it with what's already installed, and the neural voices are a pip install away. Here's what each route costs you. Narrator and Edge's Read Aloud use the built-in speech engine, but neither will save what it reads. System.Speech will: php Add-Type -AssemblyName System.Speech $s = New-Object System.Speech.Synthesis.SpeechSynthesizer What's available $s.GetInstalledVoices | ForEach-Object { $ .VoiceInfo.Name + " " + $ .VoiceInfo.Culture + " " } $s.SelectVoice "Microsoft Zira Desktop" $s.Rate = 0 -10 .. 10 $s.SetOutputToWaveFile "C:\temp\narration.wav" $s.Speak Get-Content "C:\temp\script.txt" -Raw -Encoding UTF8 $s.Dispose No install, no network, and it writes a WAV. The delivery is unmistakably synthetic, so it suits prompts and beeps more than narration. Add a voice under Settings Time & language Speech and it often doesn't appear in GetInstalledVoices . The two generations of voices live in different registry hives: SAPI 5 - what System.Speech reads Get-ChildItem 'HKLM:\SOFTWARE\Microsoft\Speech\Voices\Tokens' OneCore - what Settings installs, and Narrator uses Get-ChildItem 'HKLM:\SOFTWARE\Microsoft\Speech OneCore\Voices\Tokens' On the Windows 11 25H2 machine I checked, the SAPI hive had two voices and the OneCore hive had a third one that System.Speech could never select. If a voice you installed isn't in the list, this is why. The voices Edge reads pages with are neural, and edge-tts drives them directly: php pip install edge-tts text - MP3, with a matching .srt edge-tts --text "Hello, world " --write-media hello.mp3 --write-subtitles hello.srt edge-tts --list-voices a script file, in a chosen voice edge-tts --voice en-US-AriaNeural --file script.txt --write-media narration.mp3 edge-tts --rate=-50% --text "Hello, world " --write-media slower.mp3 edge-tts --volume=-50% --text "Hello, world " --write-media quieter.mp3 edge-tts --pitch=-50Hz --text "Hello, world " --write-media lower.mp3 Options are from the project's README and CLI help. No API key, no account, and it writes MP3 rather than WAV, which matters once a batch of scripts piles up. A subtitle file states exactly how long each line is on screen. Read that line aloud and it is nearly always longer, because people skim subtitles while a synthesizer pronounces every syllable. Translate first and the gap widens. php cue 1 00:00:00,000 -- 00:00:03,500 3.5s speech 3.2s fits cue 2 00:00:03,500 -- 00:00:07,000 3.5s speech 4.6s overruns into cue 3 cue 3 00:00:07,000 -- 00:00:12,000 5.0s speech 4.4s fits What actually works: Making something new rather than dubbing? Generate the narration first and cut the visuals to its length. Then nothing has to be squeezed. edge-tts , but they are Microsoft's service, so read the terms before shipping commercial work. Figures are from September 2026 and these terms change often. "Free to generate, but not for monetised content" is a common combination, and it's the sort of thing that surfaces after the video is published. The full version, with diagrams and a GUI option for people who don't want a terminal: Which route do you use for narration?