Cut a Particular Portion of an Audio File Using C++

In this blog, we will learn how to cut a specific portion from an audio file (like MP3 or WAV) using C++ and the FFmpeg library. This is useful when you want to extract only a part of an audio track for example, from 10 seconds to 30 seconds  without re-encoding.

Cut particular portion on an audio file using C++

Requirements:

• FFmpeg installed (sudo apt install libavformat-dev libavcodec-dev libavutil-dev)
• Basic knowledge of C++
• Audio file (like input.mp3)

Steps to Cut Audio in C++:

1. Set Up FFmpeg in C++

   extern "C" {
   #include <libavformat/avformat.h>
   #include <libavcodec/avcodec.h>
   #include <libavutil/time.h>
   }
   

    

2. Open Input File
   Use avformat_open_input() to open the original audio file.
3. Find the Audio Stream
   Detect the audio stream using av_find_best_stream().
4. Seek to Start Time
   Seek to the required starting point using av_seek_frame().
5. Extract Packets in Duration Range
   Loop through packets, check their timestamp, and write only those within the time range to the output file.
6. Save to Output File
   Write selected audio data to a new file using av_interleaved_write_frame().

Sample Command to Compile & Run:

Compile

g++ cut_audio.cpp -o cut_audio -lavformat -lavcodec -lavutil

Run

./cut_audio input.mp3 output.mp3 10 20

This will cut a

20-second portion

 starting from the

10th second

.