# Raw data overview

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Raw data access gives your app a hook into the Video SDK for Android's media pipeline: the YUV video frames, PCM audio samples, and screen-share frames the SDK is sending and receiving.

-   **Custom video effects**: background removal, filters, watermarks, AR overlays applied per-frame before frames reach remote users.
-   **Server-side processing**: transcription, recording to disk, or piping audio into your own backend.
-   **Custom sources**: feed video from a hardware capture device, a media file, or a synthesized stream into the SDK as if it were the device camera or microphone.

## Select raw data memory mode

Raw data buffers can live in stack-allocated or heap-allocated memory. The choice matters because raw frames are produced at the framerate of the source and can pile up quickly. Heap is more flexible but heavier; stack is faster but the buffer dies the moment your callback returns.

## Select raw data memory mode

In order to utilize raw data of any type, you must first select the memory mode you wish to use. The SDK supports heap-based and stack-based memory modes.

### Stack-based memory

-   Variables are allocated automatically and deallocated after the data leaves scope.
-   Variables are not accessible from or transferable to other threads.
-   Typically has faster access than heap-based memory allocation.
-   Memory space is managed by the CPU and will not become fragmented.
-   Variables cannot be resized.

See [Stack-based memory allocation](https://en.wikipedia.org/wiki/Stack-based_memory_allocation) for details.

Specify with `ZoomVideoSDKRawDataMemoryMode.ZoomVideoSDKRawDataMemoryModeStack`.

### Heap-based memory

-   Variables are allocated and deallocated manually. You must allocate and free variables to avoid memory leaks.
-   Variables can be accessed globally.
-   Has relatively slower access than stack-based memory allocation.
-   Has no guarantee on the efficiency of memory space and can become fragmented.
-   Variables can be resized.

See [Heap-based dynamic memory allocation](https://en.wikipedia.org/wiki/Memory_management#DYNAMIC) for details.

Specify with `ZoomVideoSDKRawDataMemoryMode.ZoomVideoSDKRawDataMemoryModeHeap`.

### Apply the memory mode

Set the memory mode for audio, video, and share independently when you build your `ZoomVideoSDKInitParams`. The mode you pick here applies to every raw-data callback for that stream type for the lifetime of the SDK instance.

```kotlin
val modeHeap = ZoomVideoSDKRawDataMemoryMode.ZoomVideoSDKRawDataMemoryModeHeap
val params = ZoomVideoSDKInitParams().apply {
    videoRawDataMemoryMode = modeHeap
    audioRawDataMemoryMode = modeHeap
    shareRawDataMemoryMode = modeHeap
}
```

```java
ZoomVideoSDKRawDataMemoryMode modeHeap = ZoomVideoSDKRawDataMemoryMode.ZoomVideoSDKRawDataMemoryModeHeap;
ZoomVideoSDKInitParams params = new ZoomVideoSDKInitParams();
params.videoRawDataMemoryMode = modeHeap;
params.audioRawDataMemoryMode = modeHeap;
params.shareRawDataMemoryMode = modeHeap;
```

> **Note**
>
> Unlike video, raw audio defaults to stack-based memory if you don't set `audioRawDataMemoryMode`.