I use following code snippet to decode audio files (tested with MP3,WAV,WMV).
But when it plays the audio , it just gives static sounds and crashes time to time. Any hints on what i am doing wrong here ?
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
extern "C" {
#include "libavutil/mathematics.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include <ao/ao.h>
}
void die(const char *msg)
{
fprintf(stderr,"%s\n",msg);
exit(1);
}
int main(int argc, char **argv)
{
const char* input_filename=argv[1];
//avcodec_register_all();
av_register_all();
//av_ini
AVFormatContext* container=avformat_alloc_context();
if(avformat_open_input(&container,input_filename,NULL,NULL)<0){
die("Could not open file");
}
if(av_find_stream_info(container)<0){
die("Could not find file info");
}
av_dump_format(container,0,input_filename,false);
int stream_id=-1;
int i;
for(i=0;i<container->nb_streams;i++){
if(container->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
stream_id=i;
break;
}
}
if(stream_id==-1){
die("Could not find Audio Stream");
}
AVDictionary *metadata=container->metadata;
AVCodecContext *ctx=container->streams[stream_id]->codec;
AVCodec *codec=avcodec_find_decoder(ctx->codec_id);
if(codec==NULL){
die("cannot find codec!");
}
if(avcodec_open(ctx,codec)<0){
die("Codec cannot be found");
}
//ctx=avcodec_alloc_context3(codec);
//initialize AO lib
ao_initialize();
int driver=ao_default_driver_id();
ao_sample_format sformat;
sformat.bits=16;
sformat.channels=2;
sformat.rate=44100;
sformat.byte_format=AO_FMT_NATIVE;
sformat.matrix=0;
ao_device *adevice=ao_open_live(driver,&sformat,NULL);
//end of init AO LIB
AVPacket packet;
av_init_packet(&packet);
AVFrame *frame=avcodec_alloc_frame();
int buffer_size=AVCODEC_MAX_AUDIO_FRAME_SIZE;
uint8_t buffer[buffer_size];
packet.data=buffer;
packet.size =buffer_size;
int len;
int frameFinished=0;
while(av_read_frame(container,&packet)>=0)
{
if(packet.stream_index==stream_id){
//printf("Audio Frame read \n");
int len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
//frame->
if(frameFinished){
//printf("Finished reading Frame %d %d\n",packet.size,len);
ao_play(adevice, (char*)frame->data, len);
}
}
}
av_close_input_file(container);
ao_shutdown();
return 0;
}
Ok, here is a working code sample:
int main(int argc, char **argv)
{
const char* input_filename=argv[1];
//avcodec_register_all();
av_register_all();
//av_ini
AVFormatContext* container=avformat_alloc_context();
if(avformat_open_input(&container,input_filename,NULL,NULL)<0){
die("Could not open file");
}
if(av_find_stream_info(container)<0){
die("Could not find file info");
}
av_dump_format(container,0,input_filename,false);
int stream_id=-1;
int i;
for(i=0;i<container->nb_streams;i++){
if(container->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
stream_id=i;
break;
}
}
if(stream_id==-1){
die("Could not find Audio Stream");
}
AVDictionary *metadata=container->metadata;
AVCodecContext *ctx=container->streams[stream_id]->codec;
AVCodec *codec=avcodec_find_decoder(ctx->codec_id);
if(codec==NULL){
die("cannot find codec!");
}
if(avcodec_open(ctx,codec)<0){
die("Codec cannot be found");
}
//ctx=avcodec_alloc_context3(codec);
//initialize AO lib
ao_initialize();
int driver=ao_default_driver_id();
ao_sample_format sformat;
AVSampleFormat sfmt=ctx->sample_fmt;
if(sfmt==AV_SAMPLE_FMT_U8){
printf("U8\n");
sformat.bits=8;
}else if(sfmt==AV_SAMPLE_FMT_S16){
printf("S16\n");
sformat.bits=16;
}else if(sfmt==AV_SAMPLE_FMT_S32){
printf("S32\n");
sformat.bits=32;
}
sformat.channels=ctx->channels;
sformat.rate=ctx->sample_rate;
sformat.byte_format=AO_FMT_NATIVE;
sformat.matrix=0;
ao_device *adevice=ao_open_live(driver,&sformat,NULL);
//end of init AO LIB
AVPacket packet;
av_init_packet(&packet);
AVFrame *frame=avcodec_alloc_frame();
int buffer_size=AVCODEC_MAX_AUDIO_FRAME_SIZE+ FF_INPUT_BUFFER_PADDING_SIZE;;
uint8_t buffer[buffer_size];
packet.data=buffer;
packet.size =buffer_size;
int len;
int frameFinished=0;
while(av_read_frame(container,&packet)>=0)
{
if(packet.stream_index==stream_id){
//printf("Audio Frame read \n");
int len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
//frame->
if(frameFinished){
//printf("Finished reading Frame len : %d , nb_samples:%d buffer_size:%d line size: %d \n",len,frame->nb_samples,buffer_size,frame->linesize[0]);
ao_play(adevice, (char*)frame->extended_data[0],frame->linesize[0] );
}else{
//printf("Not Finished\n");
}
}else {
printf("Someother packet possibly Video\n");
}
}
av_close_input_file(container);
ao_shutdown();
return 0;
}