ffmpeg extra audio

#include 
#define __STDC_CONSTANT_MACROS
extern "C"
{
#include 
#include 
#include 
}
#define ADTS_HEADER_LEN  7;

void adts_header(char *szAdtsHeader, int dataLen){

	int audio_object_type = 2;
	int sampling_frequency_index = 7;
	int channel_config = 2;

	int adtsLen = dataLen + 7;

	szAdtsHeader[0] = 0xff;         //syncword:0xfff                          高8bits
	szAdtsHeader[1] = 0xf0;         //syncword:0xfff                          低4bits
	szAdtsHeader[1] |= (0 << 3);    //MPEG Version:0 for MPEG-4,1 for MPEG-2  1bit
	szAdtsHeader[1] |= (0 << 1);    //Layer:0                                 2bits 
	szAdtsHeader[1] |= 1;           //protection absent:1                     1bit

	szAdtsHeader[2] = (audio_object_type - 1) << 6;            //profile:audio_object_type - 1                      2bits
	szAdtsHeader[2] |= (sampling_frequency_index & 0x0f) << 2; //sampling frequency index:sampling_frequency_index  4bits 
	szAdtsHeader[2] |= (0 << 1);                             //private bit:0                                      1bit
	szAdtsHeader[2] |= (channel_config & 0x04) >> 2;           //channel configuration:channel_config               高1bit

	szAdtsHeader[3] = (channel_config & 0x03) << 6;     //channel configuration:channel_config      低2bits
	szAdtsHeader[3] |= (0 << 5);                      //original：0                               1bit
	szAdtsHeader[3] |= (0 << 4);                      //home：0                                   1bit
	szAdtsHeader[3] |= (0 << 3);                      //copyright id bit：0                       1bit  
	szAdtsHeader[3] |= (0 << 2);                      //copyright id start：0                     1bit
	szAdtsHeader[3] |= ((adtsLen & 0x1800) >> 11);           //frame length：value   高2bits

	szAdtsHeader[4] = (uint8_t)((adtsLen & 0x7f8) >> 3);     //frame length:value    中间8bits
	szAdtsHeader[5] = (uint8_t)((adtsLen & 0x7) << 5);       //frame length:value    低3bits
	szAdtsHeader[5] |= 0x1f;                                 //buffer fullness:0x7ff 高5bits
	szAdtsHeader[6] = 0xfc;
}

int main(int argc, char *argv[])
{
	int err_code;
	char errors[1024];

	char *src_filename = NULL;
	char *dst_filename = NULL;

	FILE *dst_fd = NULL;

	int audio_stream_index = -1;
	int len;

	AVFormatContext *ofmt_ctx = NULL;
	AVOutputFormat *output_fmt = NULL;

	AVStream *out_stream = NULL;

	AVFormatContext *fmt_ctx = NULL;
	AVFrame *frame = NULL;
	AVPacket pkt;

	av_log_set_level(AV_LOG_DEBUG);

	if (argc < 3){
		av_log(NULL, AV_LOG_DEBUG, "the count of parameters should be more than three!\n");
		return -1;
	}

	src_filename = argv[1];
	dst_filename = argv[2];

	if (src_filename == NULL || dst_filename == NULL){
		av_log(NULL, AV_LOG_DEBUG, "src or dts file is null, plz check them!\n");
		return -1;
	}

	/*register all formats and codec*/
	av_register_all();


	dst_fd = fopen(dst_filename, "wb");
	if (!dst_fd) {
		av_log(NULL, AV_LOG_DEBUG, "Could not open destination file %s\n", dst_filename);
		return -1;
	}

	/*open input media file, and allocate format context*/
	if ((err_code = avformat_open_input(&fmt_ctx, src_filename, NULL, NULL)) < 0){
		av_strerror(err_code, errors, 1024);
		av_log(NULL, AV_LOG_DEBUG, "Could not open source file: %s, %d(%s)\n",
			src_filename,
			err_code,
			errors);
		return -1;
	}

	/*retrieve audio stream*/
	if ((err_code = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
		av_strerror(err_code, errors, 1024);
		av_log(NULL, AV_LOG_DEBUG, "failed to find stream information: %s, %d(%s)\n",
			src_filename,
			err_code,
			errors);
		return -1;
	}

	/*dump input information*/
	av_dump_format(fmt_ctx, 0, src_filename, 0);

	/*dump output information*/
	//av_dump_format(ofmt_ctx, 0, dst_filename, 1);

	frame = av_frame_alloc();
	if (!frame){
		av_log(NULL, AV_LOG_DEBUG, "Could not allocate frame\n");
		return AVERROR(ENOMEM);
	}

	/*initialize packet*/
	av_init_packet(&pkt);
	pkt.data = NULL;
	pkt.size = 0;

	/*find best audio stream*/
	audio_stream_index = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
	if (audio_stream_index < 0){
		av_log(NULL, AV_LOG_DEBUG, "Could not find %s stream in input file %s\n",
			av_get_media_type_string(AVMEDIA_TYPE_AUDIO),
			src_filename);
		return AVERROR(EINVAL);
	}

	/*read frames from media file*/
	while (av_read_frame(fmt_ctx, &pkt) >= 0){
		if (pkt.stream_index == audio_stream_index){
			/*
			pkt.stream_index = 0;
			av_write_frame(ofmt_ctx, &pkt);
			av_free_packet(&pkt);
			*/

			char adts_header_buf[7];
			adts_header(adts_header_buf, pkt.size);
			fwrite(adts_header_buf, 1, 7, dst_fd);

			len = fwrite(pkt.data, 1, pkt.size, dst_fd);
			if (len != pkt.size){
				av_log(NULL, AV_LOG_DEBUG, "warning, length of writed data isn't equal pkt.size(%d, %d)\n",
					len,
					pkt.size);
			}
		}
	}

	//av_write_trailer(ofmt_ctx);

	/*close input media file*/
	avformat_close_input(&fmt_ctx);
	if (dst_fd) {
		fclose(dst_fd);
	}

	return 0;
}