---
name: "afGetFrameSize"
section: "3"
platform: "linux"
package: "audiofile"
version: "0.3.6-12"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/afGetFrameSize"
---

# afGetFrameSize(3)

calculate the frame size in bytes for an audio track

## NAME

afGetFrameSize - calculate the frame size in bytes for an audio track

## SYNOPSIS

```
#include <audiofile.h>
```

```
float afGetFrameSize (AFfilehandle file, int track, int expand3to4);
```

## PARAMETERS

*file* is a valid AFfilehandle.

*track* is an integer which refers to a specific audio track in the file. At present no supported audio file format allows for more than one audio track within a file, so track should always be AF\_DEFAULT\_TRACK.

*expand3to4* is a boolean-valued integer indicating whether frame size calculation will treat 24-bit data as having a size of 3 bytes or 4 bytes.

## DESCRIPTION

afGetFrameSize returns the number of bytes in a frame in a given audio track.

A sample frame consists of one or more samples. For a monaural track, a sample frame will always contain one sample. For a stereophonic track, a sample frame will always contain two samples, one for the left channel and one for the right channel.

A non-zero value of *expand3to4* should be used when calculating the frame size for storage in memory (since 24-bit audio data is presented in memory as a 4-byte sign-extended integer), while a value of zero should be used for calculating storage on disk where no padding is added. The parameter *expand3to4* is ignored unless the specified audio track contains 24-bit audio data.

## AUTHOR

Michael Pruett \<michael@68k.org\>