FFmpeg简单使用：解封装 ---- 提取aac
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FFmpeg简单使用：过滤器 ---- h264_mp4toannexb
FFmpeg简单使用：解封装h264 ---- 提取SPS PPS
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#include <stdio.h> #include "libavutil/log.h" #include "libavformat/avio.h" #include "libavformat/avformat.h" //#define AacHeader const char* fileName = "believe.flv"; #ifdef AacHeader const char* outFileName = "outBelieve.aac"; #else const char* outFileName = "outBelieveNoHeader.aac"; #endif const int sampling_frequencies[] = { 96000, // 0x0 88200, // 0x1 64000, // 0x2 48000, // 0x3 44100, // 0x4 32000, // 0x5 24000, // 0x6 22050, // 0x7 16000, // 0x8 12000, // 0x9 11025, // 0xa 8000 // 0xb // 0xc d e f是保留的 }; int adts_header(char * const p_adts_header, const int data_length, const int profile, const int samplerate, const int channels) { int sampling_frequency_index = 3; // 默认使用48000hz int adtsLen = data_length + 7; int frequencies_size = sizeof(sampling_frequencies) / sizeof(sampling_frequencies[0]); int i = 0; for(i = 0; i < frequencies_size; i++) { if(sampling_frequencies[i] == samplerate) { sampling_frequency_index = i; break; } } if(i >= frequencies_size) { printf("unsupport samplerate:%d\n", samplerate); return -1; } p_adts_header[0] = 0xff; //syncword:0xfff 高8bits p_adts_header[1] = 0xf0; //syncword:0xfff 低4bits p_adts_header[1] |= (0 << 3); //MPEG Version:0 for MPEG-4,1 for MPEG-2 1bit p_adts_header[1] |= (0 << 1); //Layer:0 2bits p_adts_header[1] |= 1; //protection absent:1 1bit p_adts_header[2] = (profile)<<6; //profile:profile 2bits p_adts_header[2] |= (sampling_frequency_index & 0x0f)<<2; //sampling frequency index:sampling_frequency_index 4bits p_adts_header[2] |= (0 << 1); //private bit:0 1bit p_adts_header[2] |= (channels & 0x04)>>2; //channel configuration:channels 高1bit p_adts_header[3] = (channels & 0x03)<<6; //channel configuration:channels 低2bits p_adts_header[3] |= (0 << 5); //original：0 1bit p_adts_header[3] |= (0 << 4); //home：0 1bit p_adts_header[3] |= (0 << 3); //copyright id bit：0 1bit p_adts_header[3] |= (0 << 2); //copyright id start：0 1bit p_adts_header[3] |= ((adtsLen & 0x1800) >> 11); //frame length：value 高2bits p_adts_header[4] = (uint8_t)((adtsLen & 0x7f8) >> 3); //frame length:value 中间8bits p_adts_header[5] = (uint8_t)((adtsLen & 0x7) << 5); //frame length:value 低3bits p_adts_header[5] |= 0x1f; //buffer fullness:0x7ff 高5bits p_adts_header[6] = 0xfc; //11111100 //buffer fullness:0x7ff 低6bits // number_of_raw_data_blocks_in_frame： // 表示ADTS帧中有number_of_raw_data_blocks_in_frame + 1个AAC原始帧。 return 0; } int main() { printf("Hello World!\n"); // 1.打开文件 AVFormatContext *ctx = NULL; int ret = avformat_open_input(&ctx, fileName, NULL, NULL); if (ret < 0) { char buf[1024] = {0}; av_strerror(ret, buf, sizeof (buf) - 1); printf("avformat_open_input %s failed: %s\n", fileName, buf); return -1; } // 2.获取码流信息 ret = avformat_find_stream_info(ctx, NULL); if (ret < 0) { char buf[1024] = {0}; av_strerror(ret, buf, sizeof (buf) - 1); printf("avformat_find_stream_info %s failed: %s\n", fileName, buf); return -1; } // 3.获取音频流 int audioIndex = av_find_best_stream(ctx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0); if (audioIndex < 0) { printf("av_find_best_stream failed: %s\n", av_get_media_type_string(AVMEDIA_TYPE_AUDIO)); return -1; } // 4.检查是否是aac if (ctx->streams[audioIndex]->codecpar->codec_id != AV_CODEC_ID_AAC) { printf("audio codec %d is not AAC.\n", ctx->streams[audioIndex]->codecpar->codec_id); goto failed; } // 5.打开输出aac文件 FILE *fd = fopen(outFileName, "wb"); if (fd == NULL) { printf("fopen open %s failed.\n", outFileName); goto failed; } // 6.提取aac数据 AVPacket pkt; av_init_packet(&pkt); int len = 0; while (av_read_frame(ctx, &pkt) >= 0) { if (pkt.stream_index == audioIndex) { #ifdef AacHeader // 写入aac头 char adts_header_buf[7] = {0}; adts_header(adts_header_buf, pkt.size, ctx->streams[audioIndex]->codecpar->profile, ctx->streams[audioIndex]->codecpar->sample_rate, ctx->streams[audioIndex]->codecpar->channels); fwrite(adts_header_buf, 1, 7, fd); // 写adts header , ts流不适用，ts流分离出来的packet带了adts header #endif len = fwrite( pkt.data, 1, pkt.size, fd); // 写adts data if(len != pkt.size) { printf("warning, length of writed data isn't equal pkt.size(%d, %d)\n", len, pkt.size); } } av_packet_unref(&pkt); } failed: if (ctx) { avformat_close_input(&ctx); } if (fd) { fclose(fd); } return 0; }
这个有个地方要注意，flv提取的aac流没有头，需要自己手动添加：
