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

# GetXmaFrameLengthInBits

> GetXmaFrameLengthInBits

# GetXmaFrameLengthInBits

Reads the `LengthInBits` field of a specified frame.

## Syntax

```cpp theme={null}
DWORD GetXmaFrameLengthInBits(  
         const BYTE* pPacket,  
         DWORD nBitPosition  
)  
```

### Parameters

*pPacket*   \_In\_\
Type: BYTE\*

Pointer to XMA packets that contain the frame.

*nBitPosition*   \
Type: DWORD

Bit offset of the frame within this packet.

### Return value

Type: DWORD

Length, in bits.

## Remarks

As shown in the code example below, this function reads the `LengthInBits` field of a specified frame.

```cpp theme={null}

__inline DWORD GetXmaFrameLengthInBits
(
    __in_bcount(nBitPosition / 8 + 3)
    __in const BYTE* pPacket,  // Pointer to XMA packet[s] containing the frame
    DWORD nBitPosition         // Bit offset of the frame within this packet
)
{
    DWORD nRegion;
    DWORD nBytePosition = nBitPosition / 8;
    DWORD nBitOffset = nBitPosition % 8;

    if (nBitOffset < 2) // Only need to read 2 bytes (and might not be safe to read more)
    {
        nRegion = (DWORD)(pPacket[nBytePosition+0]) << 8 |
                  (DWORD)(pPacket[nBytePosition+1]);
        return (nRegion >> (1 - nBitOffset)) & 0x7FFF;  // Last 15 bits
    }
    else // Need to read 3 bytes
    {
        nRegion = (DWORD)(pPacket[nBytePosition+0]) << 16 |
                  (DWORD)(pPacket[nBytePosition+1]) << 8 |
                  (DWORD)(pPacket[nBytePosition+2]);
        return (nRegion >> (9 - nBitOffset)) & 0x7FFF;  // Last 15 bits
    }
}
```

For more information about XMA2, see [Overview of XMA2](/build/console-features/audio/overviews/xma2-overview). For an overview of the audio architecture of XBOX One, see **The sound of the future**: [The audio architecture in XBOX One](/build/console-features/audio/overviews/xbox-one-audio-architecture).

## Requirements

**Header:** xma2defs.h

**Supported platforms:** XBOX One family consoles and XBOX Series consoles

## See also

[xma2defs](/reference/audio/xma2defs/xma2defs_members)