#include "stdafx.h"
#include
#include
using namespace std;
extern "C"
{
#include "libavformat/avformat.h"
#include "libavutil/avutil.h"
#include "libavcodec/avcodec.h"
#include "libswresample/swresample.h"
#include "libavutil/frame.h"
#include "libavutil/samplefmt.h"
#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"
}
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "swscale.lib")
#pragma comment(lib, "swresample.lib")
/* PCM转AAC */
int main()
{
/* ADTS头 */
char *padts = (char *)malloc(sizeof(char) * 7);
char *mp3padts = (char *)malloc(sizeof(char) * 4);
int profile = 2; //AAC LC
int freqIdx = 4; //44.1KHz
int chanCfg = 2; //MPEG-4 Audio Channel Configuration. 1 Channel front-center,channel_layout.h
padts[0] = (char)0xFF; // 11111111 = syncword
padts[1] = (char)0xF1; // 1111 1 00 1 = syncword MPEG-2 Layer CRC
padts[2] = (char)(((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2));
padts[6] = (char)0xFC;
/*mp3padts[0] = (char)0xFF;
mp3padts[1] = (char)0xFB;
mp3padts[2] = (char)0x90;
mp3padts[3] = (char)0x04;*/
SwrContext *swr_ctx = NULL;
AVCodecContext *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVFrame *pFrame;
AVPacket pkt;
AVCodecID codec_id = AV_CODEC_ID_AAC;
FILE *fp_in;
FILE *fp_out;
char filename_in[] = "tdjm.pcm";
char filename_out[] = "audio.G711";
uint8_t **convert_data; //存储转换后的数据,再编码AAC
int i, ret, got_output;
uint8_t* frame_buf;
int size = 0;
int y_size;
int framecnt = 0;
int framenum = 100000;
avcodec_register_all();
pCodec = avcodec_find_encoder(codec_id);
if (!pCodec) {
printf("Codec not found\n");
return -1;
}
pCodecCtx = avcodec_alloc_context3(pCodec);
if (!pCodecCtx) {
printf("Could not allocate video codec context\n");
return -1;
}
pCodecCtx->codec_id = codec_id;
pCodecCtx->codec_type = AVMEDIA_TYPE_AUDIO;
pCodecCtx->sample_fmt = pCodec->sample_fmts[0];
pCodecCtx->sample_rate = 44100;
pCodecCtx->channel_layout = AV_CH_LAYOUT_STEREO;
pCodecCtx->channels = av_get_channel_layout_nb_channels(pCodecCtx->channel_layout);
//pCodecCtx->frame_size = 1024;
if ((ret = avcodec_open2(pCodecCtx, pCodec, NULL)) < 0) {
cout << "avcodec_open2 error ----> " << ret;
printf("Could not open codec\n");
return -1;
}
pCodecCtx->frame_size/* = 1024*/;
pCodecCtx->bit_rate =128000 ;
pFrame = av_frame_alloc();
pFrame->nb_samples = pCodecCtx->frame_size; //1024
pFrame->format = pCodecCtx->sample_fmt;
pFrame->channels = 2;
/* 由AV_SAMPLE_FMT_S16转为AV_SAMPLE_FMT_FLTP */
swr_ctx = swr_alloc_set_opts(
NULL,
av_get_default_channel_layout(pCodecCtx->channels),
pCodecCtx->sample_fmt,
pCodecCtx->sample_rate,
av_get_default_channel_layout(pCodecCtx->channels),
AV_SAMPLE_FMT_S16, //PCM源文件的采样格式
/*pCodecCtx->sample_rate*/44100,
0, NULL);
swr_init(swr_ctx);
/* 分配空间 */
convert_data = (uint8_t**)calloc(pCodecCtx->channels,
sizeof(*convert_data));
av_samples_alloc(convert_data, NULL,
pCodecCtx->channels, pCodecCtx->frame_size,
pCodecCtx->sample_fmt, 0);
size = av_samples_get_buffer_size(NULL, pCodecCtx->channels, pCodecCtx->frame_size, pCodecCtx->sample_fmt, 0);
frame_buf = (uint8_t *)av_malloc(size);
/* 此时data[0],data[1]分别指向frame_buf数组起始、中间地址 */
ret = avcodec_fill_audio_frame(pFrame, pCodecCtx->channels, pCodecCtx->sample_fmt, (const uint8_t*)frame_buf, size, 0);
if (ret < 0)
{
cout << "avcodec_fill_audio_frame error ";
return 0;
}
//Input raw data
fp_in = fopen(filename_in, "rb");
if (!fp_in) {
printf("Could not open %s\n", filename_in);
return -1;
}
//Output bitstream
fp_out = fopen(filename_out, "wb");
if (!fp_out) {
printf("Could not open %s\n", filename_out);
return -1;
}
//Encode
for (i = 0; i < framenum; i++) {
av_init_packet(&pkt);
pkt.data = NULL;
pkt.size = 0;
//Read raw data
if (fread(frame_buf, 1, 4096, fp_in) <= 0) {
printf("Failed to read raw data! \n");
return -1;
}
else if (feof(fp_in)) {
break;
}
/* 转换数据,令各自声道的音频数据存储在不同的数组(分别由不同指针指向)*/
pCodecCtx->sample_fmt;
swr_convert(swr_ctx, convert_data, pCodecCtx->frame_size,
(const uint8_t**)pFrame->data, pCodecCtx->frame_size);
/* 将转换后的数据复制给pFrame */
int length = pCodecCtx->frame_size * av_get_bytes_per_sample(pCodecCtx->sample_fmt);
memcpy(pFrame->data[0], convert_data[0], length);
memcpy(pFrame->data[1], convert_data[1], length);
pFrame->pts = i*100;
ret = avcodec_encode_audio2(pCodecCtx, &pkt, pFrame, &got_output);
if (ret < 0) {
cout << "error encoding";
return -1;
}
if (pkt.data == NULL)
{
av_free_packet(&pkt);
continue;
}
if (got_output) {
framecnt++;
padts[3] = (char)(((chanCfg & 3) << 6) + ((7 + pkt.size) >> 11));
padts[4] = (char)(((7 + pkt.size) & 0x7FF) >> 3);
padts[5] = (char)((((7 + pkt.size) & 7) << 5) + 0x1F);
fwrite(padts, 7, 1, fp_out);
fwrite(pkt.data, 1, pkt.size, fp_out);
av_free_packet(&pkt);
}
}
//Flush Encoder
for (got_output = 1; got_output; i++) {
ret = avcodec_encode_audio2(pCodecCtx, &pkt, NULL, &got_output);
if (ret < 0) {
printf("Error encoding frame\n");
return -1;
}
if (got_output) {
padts[3] = (char)(((chanCfg & 3) << 6) + ((7 + pkt.size) >> 11));
padts[4] = (char)(((7 + pkt.size) & 0x7FF) >> 3);
padts[5] = (char)((((7 + pkt.size) & 7) << 5) + 0x1F);
//
fwrite(padts, 7, 1, fp_out);
// fwrite(mp3padts, 4, 1, fp_out);
fwrite(pkt.data, 1, pkt.size, fp_out);
av_free_packet(&pkt);
}
}
fclose(fp_out);
avcodec_close(pCodecCtx);
av_free(pCodecCtx);
av_freep(&pFrame->data[0]);
av_frame_free(&pFrame);
av_freep(&convert_data[0]);
free(convert_data);
return 0;
}
有两个疑问,希望知道原理的博友能告知:
1、AV_CODEC_ID_PCM_ALAW这个为G711A编解码器,编码器的frame_size为0 ,不知道怎么回事?需要自己指定,比如和AAC的一样为1024。
2、转为MP3、G711A的时候不需要加头,但是为什么AAC的需要加头呢?