音视频（51-52）

注意：本人的环境为qt6.11.1 ffmpeg-5.16.2 将dll拷贝到exe文件下进行调试

#include <stdio.h> #include <libavformat/avformat.h> int main(int argc, char **argv) { //打开网络流。这里如果只需要读取本地媒体文件，不需要用到网络功能，可以不用加上这一句 // avformat_network_init(); const char *default_filename = "E:/2025/ffmpeg/believe.mp4"; char *in_filename = NULL; if(argv[1] == NULL) { in_filename = default_filename; } else { in_filename = argv[1]; } printf("1111in_filename = %s\n", in_filename); //AVFormatContext是描述一个媒体文件或媒体流的构成和基本信息的结构体 AVFormatContext *ifmt_ctx = NULL; // 输入文件的demux int videoindex = -1; // 视频索引 int audioindex = -1; // 音频索引 // 打开文件，主要是探测协议类型，如果是网络文件则创建网络链接 int ret = avformat_open_input(&ifmt_ctx, in_filename, NULL, NULL); if (ret < 0) //如果打开媒体文件失败，打印失败原因 { char buf[1024] = { 0 }; av_strerror(ret, buf, sizeof(buf) - 1); printf("open %s failed:%s\n", in_filename, buf); goto failed; } ret = avformat_find_stream_info(ifmt_ctx, NULL); if (ret < 0) //如果打开媒体文件失败，打印失败原因 { char buf[1024] = { 0 }; av_strerror(ret, buf, sizeof(buf) - 1); printf("avformat_find_stream_info %s failed:%s\n", in_filename, buf); goto failed; } //打开媒体文件成功 printf_s("\n==== av_dump_format in_filename:%s ===\n", in_filename); av_dump_format(ifmt_ctx, 0, in_filename, 0); printf_s("\n==== av_dump_format finish =======\n\n"); // url: 调用avformat_open_input读取到的媒体文件的路径/名字 printf("media name:%s\n", ifmt_ctx->url); // nb_streams: nb_streams媒体流数量 printf("stream number:%d\n", ifmt_ctx->nb_streams); // bit_rate: 媒体文件的码率,单位为bps printf("media average ratio:%lldkbps\n",(int64_t)(ifmt_ctx->bit_rate/1024)); // 时间 int total_seconds, hour, minute, second; // duration: 媒体文件时长，单位微妙 total_seconds = (ifmt_ctx->duration) / AV_TIME_BASE; // 1000us = 1ms, 1000ms = 1秒 hour = total_seconds / 3600; minute = (total_seconds % 3600) / 60; second = (total_seconds % 60); //通过上述运算，可以得到媒体文件的总时长 printf("total duration: %02d:%02d:%02d\n", hour, minute, second); printf("\n"); /* * 老版本通过遍历的方式读取媒体文件视频和音频的信息 * 新版本的FFmpeg新增加了函数av_find_best_stream，也可以取得同样的效果 */ for (uint32_t i = 0; i < ifmt_ctx->nb_streams; i++) { AVStream *in_stream = ifmt_ctx->streams[i];// 音频流、视频流、字幕流 //如果是音频流，则打印音频的信息 if (AVMEDIA_TYPE_AUDIO == in_stream->codecpar->codec_type) { printf("----- Audio info:\n"); // index: 每个流成分在ffmpeg解复用分析后都有唯一的index作为标识 printf("index:%d\n", in_stream->index); // sample_rate: 音频编解码器的采样率，单位为Hz printf("samplerate:%dHz\n", in_stream->codecpar->sample_rate); // codecpar->format: 音频采样格式 if (AV_SAMPLE_FMT_FLTP == in_stream->codecpar->format) { printf("sampleformat:AV_SAMPLE_FMT_FLTP\n"); } else if (AV_SAMPLE_FMT_S16P == in_stream->codecpar->format) { printf("sampleformat:AV_SAMPLE_FMT_S16P\n"); } // channels: 音频信道数目 printf("channel number:%d\n", in_stream->codecpar->channels); // codec_id: 音频压缩编码格式 if (AV_CODEC_ID_AAC == in_stream->codecpar->codec_id) { printf("audio codec:AAC\n"); } else if (AV_CODEC_ID_MP3 == in_stream->codecpar->codec_id) { printf("audio codec:MP3\n"); } else { printf("audio codec_id:%d\n", in_stream->codecpar->codec_id); } // 音频总时长，单位为秒。注意如果把单位放大为毫秒或者微妙，音频总时长跟视频总时长不一定相等的 if(in_stream->duration != AV_NOPTS_VALUE) { int duration_audio = (in_stream->duration) * av_q2d(in_stream->time_base); //将音频总时长转换为时分秒的格式打印到控制台上 printf("audio duration: %02d:%02d:%02d\n", duration_audio / 3600, (duration_audio % 3600) / 60, (duration_audio % 60)); } else { printf("audio duration unknown"); } printf("\n"); audioindex = i; // 获取音频的索引 } else if (AVMEDIA_TYPE_VIDEO == in_stream->codecpar->codec_type) //如果是视频流，则打印视频的信息 { printf("----- Video info:\n"); printf("index:%d\n", in_stream->index); // avg_frame_rate: 视频帧率,单位为fps，表示每秒出现多少帧 printf("fps:%lffps\n", av_q2d(in_stream->avg_frame_rate)); if (AV_CODEC_ID_MPEG4 == in_stream->codecpar->codec_id) //视频压缩编码格式 { printf("video codec:MPEG4\n"); } else if (AV_CODEC_ID_H264 == in_stream->codecpar->codec_id) //视频压缩编码格式 { printf("video codec:H264\n"); } else { printf("video codec_id:%d\n", in_stream->codecpar->codec_id); } // 视频帧宽度和帧高度 printf("width:%d height:%d\n", in_stream->codecpar->width, in_stream->codecpar->height); //视频总时长，单位为秒。注意如果把单位放大为毫秒或者微妙，音频总时长跟视频总时长不一定相等的 if(in_stream->duration != AV_NOPTS_VALUE) { int duration_video = (in_stream->duration) * av_q2d(in_stream->time_base); printf("video duration: %02d:%02d:%02d\n", duration_video / 3600, (duration_video % 3600) / 60, (duration_video % 60)); //将视频总时长转换为时分秒的格式打印到控制台上 } else { printf("video duration unknown"); } printf("\n"); videoindex = i; } } AVPacket *pkt = av_packet_alloc(); int pkt_count = 0; int print_max_count = 10; printf("\n-----av_read_frame start\n"); while (1) { ret = av_read_frame(ifmt_ctx, pkt); if (ret < 0) { printf("av_read_frame end\n"); break; } if(pkt_count++ < print_max_count) { if (pkt->stream_index == audioindex) { printf("audio pts: %lld\n", pkt->pts); printf("audio dts: %lld\n", pkt->dts); printf("audio size: %d\n", pkt->size); printf("audio pos: %lld\n", pkt->pos); printf("audio duration: %lf\n\n", pkt->duration * av_q2d(ifmt_ctx->streams[audioindex]->time_base)); } else if (pkt->stream_index == videoindex) { printf("video pts: %lld\n", pkt->pts); printf("video dts: %lld\n", pkt->dts); printf("video size: %d\n", pkt->size); printf("video pos: %lld\n", pkt->pos); printf("video duration: %lf\n\n", pkt->duration * av_q2d(ifmt_ctx->streams[videoindex]->time_base)); } else { printf("unknown stream_index:\n", pkt->stream_index); } } av_packet_unref(pkt); } if(pkt) av_packet_free(&pkt); failed: if(ifmt_ctx) avformat_close_input(&ifmt_ctx); getchar(); //加上这一句，防止程序打印完信息马上退出 return 0; }

52

#include <stdio.h> #include <libavutil/log.h> #include <libavformat/avio.h> #include <libavformat/avformat.h> #include <libavcodec/codec.h> #include <libavcodec/avcodec.h> #define ADTS_HEADER_LEN 7; 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(int argc, char *argv[]) { int ret = -1; char errors[1024]; char *in_filename = NULL; char *aac_filename = NULL; FILE *aac_fd = NULL; int audio_index = -1; int len = 0; AVFormatContext *ifmt_ctx = NULL; AVPacket pkt; // 设置打印级别 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; } in_filename = argv[1]; // 输入文件 aac_filename = argv[2]; // 输出文件 if(in_filename == NULL || aac_filename == NULL) { av_log(NULL, AV_LOG_DEBUG, "src or dts file is null, plz check them!\n"); return -1; } aac_fd = fopen(aac_filename, "wb"); if (!aac_fd) { av_log(NULL, AV_LOG_DEBUG, "Could not open destination file %s\n", aac_filename); return -1; } // 打开输入文件 if((ret = avformat_open_input(&ifmt_ctx, in_filename, NULL, NULL)) < 0) { av_strerror(ret, errors, 1024); av_log(NULL, AV_LOG_DEBUG, "Could not open source file: %s, %d(%s)\n", in_filename, ret, errors); return -1; } // 获取解码器信息 if((ret = avformat_find_stream_info(ifmt_ctx, NULL)) < 0) { av_strerror(ret, errors, 1024); av_log(NULL, AV_LOG_DEBUG, "failed to find stream information: %s, %d(%s)\n", in_filename, ret, errors); return -1; } // dump媒体信息 av_dump_format(ifmt_ctx, 0, in_filename, 0); // 初始化packet av_init_packet(&pkt); // 查找audio对应的steam index audio_index = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0); if(audio_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), in_filename); return AVERROR(EINVAL); } // 打印AAC级别 printf("audio profile:%d, FF_PROFILE_AAC_LOW:%d\n", ifmt_ctx->streams[audio_index]->codecpar->profile, FF_PROFILE_AAC_LOW); if(ifmt_ctx->streams[audio_index]->codecpar->codec_id != AV_CODEC_ID_AAC) { printf("the media file no contain AAC stream, it's codec_id is %d\n", ifmt_ctx->streams[audio_index]->codecpar->codec_id); goto failed; } // 读取媒体文件，并把aac数据帧写入到本地文件 while(av_read_frame(ifmt_ctx, &pkt) >=0 ) { if(pkt.stream_index == audio_index) { char adts_header_buf[7] = {0}; adts_header(adts_header_buf, pkt.size, ifmt_ctx->streams[audio_index]->codecpar->profile, ifmt_ctx->streams[audio_index]->codecpar->sample_rate, ifmt_ctx->streams[audio_index]->codecpar->channels); fwrite(adts_header_buf, 1, 7, aac_fd); // 写adts header , ts流不适用，ts流分离出来的packet带了adts header len = fwrite( pkt.data, 1, pkt.size, aac_fd); // 写adts data 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_packet_unref(&pkt); } failed: // 关闭输入文件 if(ifmt_ctx) { avformat_close_input(&ifmt_ctx); } if(aac_fd) { fclose(aac_fd); } return 0; }