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

# Supported Languages, Formats, and Limits

> Reference for DeepL Voice API language availability, supported audio codecs and containers, and session limits.

## Supported languages

Translation is always provided by DeepL. For some languages, transcription and translated speech are provided by external service partners. All source languages can be translated into any target language.

<Card>
  | **Language**                           | **Transcription** | **Translation** | <Badge color="green">closed beta</Badge><br />Translated Speech |
  | :------------------------------------- | :---------------: | :-------------: | :-------------------------------------------------------------: |
  | Arabic                                 |         ⎋         |        ✓        |                                ⎋                                |
  | Bengali                                |         ⎋         |        ✓        |                                —                                |
  | Bulgarian                              |         ⎋         |        ✓        |                                ⎋                                |
  | Chinese (Simplified/Traditional)       |         ✓         |        ✓        |                                ✓                                |
  | Croatian                               |         ⎋         |        ✓        |                                —                                |
  | Czech                                  |         ✓         |        ✓        |                                ⎋                                |
  | Danish                                 |         ⎋         |        ✓        |                                ⎋                                |
  | Dutch                                  |         ✓         |        ✓        |                                ✓                                |
  | English (American/British)             |         ✓         |        ✓        |                                ✓                                |
  | Estonian                               |         ⎋         |        ✓        |                                —                                |
  | Finnish                                |         ⎋         |        ✓        |                                ⎋                                |
  | French                                 |         ✓         |        ✓        |                                ✓                                |
  | German                                 |         ✓         |        ✓        |                                ✓                                |
  | Greek                                  |         ⎋         |        ✓        |                                ⎋                                |
  | Hebrew                                 |         ⎋         |        ✓        |                                —                                |
  | Hindi <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |                                ⎋                                |
  | Hungarian                              |         ⎋         |        ✓        |                                ⎋                                |
  | Indonesian                             |         ✓         |        ✓        |                                ⎋                                |
  | Irish                                  |         ⎋         |        ✓        |                                —                                |
  | Italian                                |         ✓         |        ✓        |                                ✓                                |
  | Japanese                               |         ✓         |        ✓        |                                ✓                                |
  | Korean                                 |         ✓         |        ✓        |                                ✓                                |
  | Latvian                                |         ⎋         |        ✓        |                                —                                |
  | Lithuanian                             |         ⎋         |        ✓        |                                —                                |
  | Malay <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |                                ⎋                                |
  | Maltese                                |         ⎋         |        ✓        |                                —                                |
  | Norwegian Bokmål                       |         ⎋         |        ✓        |                                ⎋                                |
  | Polish                                 |         ✓         |        ✓        |                                ✓                                |
  | Portuguese (Brazil/Portugal)           |         ✓         |        ✓        |                                ✓                                |
  | Romanian                               |         ✓         |        ✓        |                                ⎋                                |
  | Russian                                |         ✓         |        ✓        |                                ✓                                |
  | Slovak                                 |         ⎋         |        ✓        |                                ⎋                                |
  | Slovenian                              |         ⎋         |        ✓        |                                —                                |
  | Spanish                                |         ✓         |        ✓        |                                ✓                                |
  | Swedish                                |         ✓         |        ✓        |                                ✓                                |
  | Thai                                   |         ⎋         |        ✓        |                                —                                |
  | Tagalog                                |         ⎋         |        ✓        |                                —                                |
  | Tamil <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |                                ⎋                                |
  | Turkish                                |         ✓         |        ✓        |                                ✓                                |
  | Ukrainian                              |         ✓         |        ✓        |                                ⎋                                |
  | Vietnamese                             |         ⎋         |        ✓        |                                ⎋                                |

  ✓ provided by DeepL / ⎋ provided by an external service partner / — not available
</Card>

<Warning>
  Transcription provided by external service partners (marked with ⎋) cannot yet auto-detect the source language,
  which you must therefore specify explicitly.
</Warning>

To retrieve supported languages and feature availability programmatically, call [`GET /v3/languages?resource=voice`](/docs/languages/using-the-languages-api) and check for the `transcription` and `translated_speech` feature keys. The `external` flag on these features indicates if they are provided by an external service partner.

## Supported audio formats

The API supports common combinations of streaming codecs and containers with a single-channel (mono) audio stream.

| **Audio Codec**               | **Audio Container**                 | **Recommended Bitrate**                              |
| :---------------------------- | :---------------------------------- | :--------------------------------------------------- |
| **PCM** <Icon icon="star" />  | **-**                               | **256 kbps (16kHz), default recommendation**         |
| **OPUS** <Icon icon="star" /> | **Matroska / MPEG-TS / Ogg / WebM** | **32 kbps, recommended for low bandwidth scenarios** |
| AAC                           | Matroska / MPEG-TS                  | 96 kbps                                              |
| FLAC                          | FLAC / Matroska / Ogg               | 256 kbps (16kHz)                                     |
| MP3                           | MPEG / Matroska                     | 128 kbps                                             |

For the detailed list of supported input audio formats, see [Source Media Content Type](/api-reference/voice/request-session#body-source-media-content-type). For supported output audio formats, see [Target Media Content Type](/api-reference/voice/request-session#body-target-media-content-type).

## Session limits

* Maximum 5 translation targets per session (including translated speech targets)
* Maximum 1 translated speech target per session
* Audio chunk size: should not exceed 100 kilobytes or 1 second duration
* Recommended chunk duration: 50-250 milliseconds for low latency
* Audio stream speed: maximum 2x real-time
* Timeout: if no data is received for 30 seconds, the session is terminated
* Maximum connection duration: after 1 hour, the connection is closed. Establish a new connection by [reconnecting](/api-reference/voice/reconnect-session) to the session
* Using any given token more than once to establish a WebSocket connection terminates the associated session immediately for security reasons

If you need more translation targets or translated speech targets than these limits allow, open multiple concurrent sessions over the same source audio.