> ## Documentation Index
> Fetch the complete documentation index at: https://typecast.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Synthesis

> Generate speech with the CLI and control voices, models, emotions, and output files.

## Feature map

| Need                            | Use                                                        |
| ------------------------------- | ---------------------------------------------------------- |
| Immediate local playback        | `cast "text"`                                              |
| Reusable audio file             | `--out file.wav` or `--out file.mp3 --format mp3`          |
| Realtime-feeling agent response | Default playback without `--out`                           |
| Timestamp JSON                  | `--timestamps-out file.json`                               |
| SRT or WebVTT subtitles         | `--timestamps-out file.srt` or `--timestamps-out file.vtt` |
| Custom cloned voice             | `--voice-id uc_xxx` after `cast voices clone`              |

## Basic usage

```bash theme={null}
# Play immediately
cast "Hello, world!"

# Use a specific voice
cast "Hello, world!" --voice-id tc_xxx

# Save to WAV file
cast "Hello, world!" --out hello.wav

# Save to MP3 file
cast "Hello, world!" --out hello.mp3 --format mp3

# Save audio with SRT subtitles
cast "Hello, world. This is a test." --out hello.wav --timestamps-out hello.srt
```

By default, `cast` plays audio immediately. Use `--out` to save a WAV or MP3 file instead.

<Info>
  CLI's immediate playback is the fastest terminal workflow for local realtime feedback. For API-level chunked streaming (`POST /v1/text-to-speech/stream`), see [Streaming TTS](/quickstart#stream-audio-in-real-time) and the SDK docs.
</Info>

## Options

| Flag                  | Description                                             | Default                          |
| --------------------- | ------------------------------------------------------- | -------------------------------- |
| `--voice-id`          | Voice ID                                                | `tc_60e5426de8b95f1d3000d7b5`    |
| `--model`             | Model (`ssfm-v30`, `ssfm-v21`)                          | `ssfm-v30`                       |
| `--language`          | Language code (ISO 639-3)                               | auto-detected                    |
| `--emotion`           | Emotion type: `smart`, `preset`                         |                                  |
| `--emotion-preset`    | Preset emotion (requires `--emotion preset`)            |                                  |
| `--emotion-intensity` | Emotion intensity 0.0-2.0 (requires `--emotion preset`) | `1.0`                            |
| `--prev-text`         | Previous sentence for context (`--emotion smart` only)  |                                  |
| `--next-text`         | Next sentence for context (`--emotion smart` only)      |                                  |
| `--volume`            | Volume (0-200)                                          | `100`                            |
| `--pitch`             | Pitch in semitones (-12 to +12)                         | `0`                              |
| `--tempo`             | Tempo multiplier (0.5-2.0)                              | `1.0`                            |
| `--format`            | Output format (`wav`, `mp3`)                            | `wav`                            |
| `--seed`              | Unsigned integer seed for reproducible output (`>= 0`)  |                                  |
| `--out`               | Save to file instead of playing                         |                                  |
| `--timestamps-out`    | Save timestamp output to JSON, SRT, or WebVTT           |                                  |
| `--timestamps-format` | Timestamp output format (`json`, `srt`, `vtt`)          | inferred from `--timestamps-out` |
| `--granularity`       | Timestamp granularity (`word`, `char`, `both`)          | server default                   |

## Models

| Model      | Languages | Emotions                             | Latency  |
| ---------- | --------- | ------------------------------------ | -------- |
| `ssfm-v30` | 37        | 7 presets + smart emotion            | Standard |
| `ssfm-v21` | 27        | 4 presets: normal, happy, sad, angry | Low      |

```bash theme={null}
cast "Hello, world!" --model ssfm-v21
```

## Emotions

<Tabs>
  <Tab title="Smart Emotion">
    AI automatically infers the appropriate emotion from the text. Smart emotion is available with `ssfm-v30`.

    ```bash theme={null}
    cast "I just got promoted!" --emotion smart
    ```

    Provide surrounding sentences for better context:

    ```bash theme={null}
    cast "I just got promoted!" --emotion smart \
      --prev-text "I have been working so hard this year." \
      --next-text "Let's celebrate tonight!"
    ```
  </Tab>

  <Tab title="Preset Emotion">
    Choose a specific emotion with `--emotion-preset`, and control its strength with `--emotion-intensity`.

    | Model      | Available Presets                                                  |
    | ---------- | ------------------------------------------------------------------ |
    | `ssfm-v30` | `normal`, `happy`, `sad`, `angry`, `whisper`, `toneup`, `tonedown` |
    | `ssfm-v21` | `normal`, `happy`, `sad`, `angry`                                  |

    ```bash theme={null}
    cast "Hello, world!" --emotion preset --emotion-preset happy
    cast "Hello, world!" --emotion preset --emotion-preset happy --emotion-intensity 2.0
    cast "Hello, world!" --emotion preset --emotion-preset whisper --emotion-intensity 0.5
    cast "Hello, world!" --model ssfm-v21 --emotion preset --emotion-preset sad
    ```
  </Tab>
</Tabs>