Realtime
Create a transcription session
Creates an ephemeral API token and Realtime transcription session for use in client-side applications.
Request Body
Create an ephemeral API key with the given session configuration.
turn_detection
OpenAI.RealtimeTranscriptionSessionCreateRequestTurnDetection
type
enum
input_audio_noise_reduction
OpenAI.RealtimeTranscriptionSessionCreateRequestInputAudioNoiseReduction
type
enum
Type of noise reduction. near_field is for close-talking microphones such as headphones, far_field is for far-field microphones such as laptop or conference room microphones.
input_audio_format
enum
The format of input audio. Options are pcm16, g711_ulaw, or g711_alaw. For pcm16, input audio must be 16-bit PCM at a 24kHz sample rate, single channel (mono), and little-endian byte order.
input_audio_transcription
OpenAI.AudioTranscription
model
string | enum
The model to use for transcription. Current options are whisper-1, gpt-transcribe, gpt-live-transcribe, gpt-4o-mini-transcribe, gpt-4o-mini-transcribe-2025-12-15, gpt-4o-transcribe, gpt-4o-transcribe-diarize, and gpt-realtime-whisper. Use gpt-4o-transcribe-diarize when you need diarization with speaker labels.
enum
language
string
The language of the input audio. Supplying the input language in ISO-639-1 (e.g. en) format will improve accuracy and latency.
languages
string[]
Possible languages of the input audio, in ISO-639-1 format. Supported by gpt-transcribe and gpt-live-transcribe.
keywords
string[]
Words or phrases to guide transcription of the input audio. Supported by gpt-transcribe and gpt-live-transcribe.
prompt
string
An optional text to guide the model's style or continue a previous audio segment. For whisper-1, the prompt is a list of keywords. For gpt-4o-transcribe models (excluding gpt-4o-transcribe-diarize), the prompt is a free text string, for example "expect words related to technology". Prompt is not supported with gpt-realtime-whisper in GA Realtime sessions.
delay
enum
Controls how long the model waits before emitting transcription text. Higher values can improve transcription accuracy at the cost of latency. Only supported with gpt-realtime-whisper in GA Realtime sessions.
include
enum[]
The set of items to include in the transcription. Current available items are: item.input_audio_transcription.logprobs
Responses
The request has succeeded.
Body
client_secret
OpenAI.RealtimeTranscriptionSessionCreateResponseClientSecret
required
modalities
enum[]
The set of modalities the model can respond with. To disable audio, set this to ["text"].
input_audio_format
string
The format of input audio. Options are pcm16, g711_ulaw, or g711_alaw.
input_audio_transcription
OpenAI.AudioTranscriptionResponse
model
string | enum
The model used for transcription. Current options are whisper-1, gpt-transcribe, gpt-live-transcribe, gpt-4o-mini-transcribe, gpt-4o-mini-transcribe-2025-12-15, gpt-4o-transcribe, gpt-4o-transcribe-diarize, and gpt-realtime-whisper.
enum
language
string | null
The language of the input audio.
languages
string[]
The possible input audio languages configured for transcription, in ISO-639-1 format.
prompt
string
The prompt configured for input audio transcription, when present.
turn_detection
OpenAI.RealtimeTranscriptionSessionCreateResponseTurnDetection
type
enum
required
Request
curl -X POST https://api.openai.com/v1/realtime/transcription_sessions \
-H "Authorization: Bearer $OPENAI_API_KEY" \
-H "Content-Type: application/json" \
-d '{}'Response
{
"id": "sess_BBwZc7cFV3XizEyKGDCGL",
"object": "realtime.transcription_session",
"modalities": ["audio", "text"],
"turn_detection": {
"type": "server_vad",
"threshold": 0.5,
"prefix_padding_ms": 300,
"silence_duration_ms": 200
},
"input_audio_format": "pcm16",
"input_audio_transcription": {
"model": "gpt-4o-transcribe",
"language": null,
"prompt": ""
},
"client_secret": null
}