How to update audio codec of audiofile using ffmpeg

[Jaswinder]

I want to convert abc.avi file to abc.mp3 by using ffmpeg i am able to get existing codec of this file by using this code.
@#include <QtCore/QCoreApplication>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <QDebug>
#include <QHash>
extern"C"
{
#include "avformat.h"
#include "avcodec.h"

#include <swscale.h>
}

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

AVFrame* frame = avcodec_alloc_frame();


av_register_all();

AVFormatContext *formatContext = avformat_alloc_context();
if(avformat_open_input(&formatContext,"/Users/local/abc.avi",NULL,NULL)!= 0)
{
    av_free(frame);
}

QHash<QString, QString> ap;
av_find_stream_info(formatContext);
av_read_play(formatContext);

if(!formatContext)
{

    qDebug()<<"not return";
}
QString text = QString("%1").arg(int(formatContext->duration/AV_TIME_BASE)/60);
text +=":"+QString("%1").arg(int(formatContext->duration/AV_TIME_BASE)`,2,10,QChar('0'));
qDebug()<<"duration"<<text;
qDebug()<<"bitrate"<&lt;formatContext-&gt;bit_rate/1000;
qDebug()<<"File Size"<&lt;formatContext-&gt;file_size/1024;

AVCodecContext *c = 0;
uint wma_idx;
for (wma_idx = 0; wma_idx &lt; formatContext-&gt;nb_streams; wma_idx++)
{
    c = formatContext->streams[wma_idx]->codec;
    if (c->codec_type == AVMEDIA_TYPE_VIDEO)
    {
        qDebug()<<"vedio Type" <<c->codec_type;
    }
    if (c->codec_type == AVMEDIA_TYPE_AUDIO)
    {
        qDebug()<<"Audio" <<c->codec_type;
    }

    AVCodec *pCodec;

    // Find the decoder for the video stream
    pCodec=avcodec_find_decoder(c->codec_id);
    if(pCodec==NULL) {
        qDebug()<<"code not read";
    }
    qDebug()<<"codec name"<<pCodec->name;

}

return a.exec&#40;&#41;;

}
@

By this code i can get the existing codec of this file like audio codec mp3 and vedio codec mpeg4.
Now i want to convert this vedio file to mp3 file with mp3 codec . i want to update codec of this file can any one address me how to do this task.
Thanks in advance.

[tobias.hunger]

Have you considered asking the ffmpeg people? I am sure they have more experience working their library than the people here.

[AttilaPethe]

Did you manage to do the project? I am interested too!