---
title: "Batch-To-Stream Audio Merger"
slug: "dataflow-nodes-batch-to-stream-audio-merger"
updated: 2025-08-01T09:19:41Z
published: 2025-08-01T09:19:41Z
canonical: "docs.knovvu.com/dataflow-nodes-batch-to-stream-audio-merger"
---

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

# Batch-To-Stream Audio Merger

Merges two incoming audio together and outputs it as a stream. For the node to work correctly, it needs to be used in a streaming project. Supports [Barge-In](/v1/docs/dataflow-nodes-batch-to-stream-audio-merger#bargein) as of *Data Flow 4.1.0*.

## Parameters
| <div style="width:170px">name</div> | description | <div style="width:120px">default</div> |
|---|---|---|
| Stream Input Volume Percentage |Changes the volume of the incoming streaming audio | 100 |

## Inputs

### Audio
&emsp; Accepts Streaming and Batch audio from a single channel. 


### Events
| name | description | known nodes that generate this event |
|---|---|---|
| [Start of TTS Fragment](/v1/docs/events#start-of-tts-fragment)| Signals the start of a TTS segment. | TTS Http |
| [Speech Started](/v1/docs/events#speech-started) | Indicates Barge-In. | Vad |
| [End of TTS Fragment](/v1/docs/events#end-of-tts-fragment)| Signals the start of a TTS segment. | TTS Http |
| [Speech Ended](/v1/docs/events#speech-ended) | Signals the end of Barge-In. | Vad |

## Outputs

### Audio
&emsp;Streams one-channel audio from the output connection. 

### Events

|  <div style="width:120px">name</div> | description |
|---|---|
|[Merge Audio Started](/v1/docs/events#merge-audio-started)	| Signals the start of audio merging. Sent only when batch audio queue is not empty anymore.  |
|[Merge Audio Ended](/v1/docs/events#merge-audio-ended)	|Signals the end of audio merging. Sent only when batch audio queue is emptied out. |





## Remarks
### Working Principle

- The node outputs the streaming audio instantaneously no matter what. 
- Whenever an audio batch is received from a TTS node or a VAD node, the audio batch will be kept in a queue.
- If the batch audio queue is empty, the output stream is the same as the input.
- If the batch audio queue is not empty, the incoming streaming audio will be merged with the first audio in queue and streamed in the incoming rate.
<center>

    ![Untitled video - Made with Clipchamp \(2\).gif](https://cdn.document360.io/9bca2910-6a3b-4224-9470-43f91f9a6d57/Images/Documentation/Untitled%20video%20-%20Made%20with%20Clipchamp%20%282%29.gif){height="" width=""}

</center>

:::(Info) (Overflow )
If the merged audio is too loud for the audio format, the node will automatically normalize the output stream. 
:::
#### Barge-In

Barge-In occurs when a the connected VAD node detects speech. If a [Speech Started](/v1/docs/events#speech-started) is received during a merge, the merge stops, and **only the streaming audio source is outputted**. 
The merging will continue normally **after** a [Speech Ended](/v1/docs/events#speech-ended) event is received.  

#### Project Structure
<center>

![image.png](https://cdn.document360.io/9bca2910-6a3b-4224-9470-43f91f9a6d57/Images/Documentation/image-THX02YSE.png){height="" width=""}

</center>
    
The figure above, is a basic project that supports simultaneous translation with the Barge-In feature.


### Supported flow types
Stream

## Release Notes

<div style="max-height: 200px; overflow-y: auto; overflow-x: hidden">
    <details>
      <summary> <strong> v4.2.0</strong>  </summary>
          <ul>
              <li>Added Merge audio started and ended events.</li>
          </ul>
  </details>  
    <details>
      <summary> <strong> v4.1.0</strong>  </summary>
          <ul>
              <li>Added Barge-In support.</li>
          </ul>
  </details>  
    <details>
      <summary> <strong> v3.7.0</strong>  </summary>
          <ul>
              <li>Added Stream Input Volume Percentage as a Parameter.</li>
          </ul>
  </details>  
  <details>
      <summary> <strong> v3.4.0</strong>  </summary>
       <ul>
              <li> Introduced Node.</li>
          </ul>
  </details>
</div>