FFmpeg简单使用：解封装基本流程

解封装流程

1.分配解复用器上下文avformat_alloc_context

2.根据url打开本地文件或网络流avformat_open_input

3.读取媒体的部分数据包以获取码流信息avformat_find_stream_info

4.读取码流信息&＃xff1a;循环处理

　　4.1 从文件中读取数据包av_read_frame

　　4.2 定位文件avformat_seek_file或av_seek_frame

5.关闭解复用器avformat_close_input

编码&＃xff1a;

#include
#include int main(int argc, char **argv)
{// 1. 打开文件const char *ifilename &＃61; "believe.flv";printf("in_filename &＃61; %s\n", ifilename);// 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 &＃61; NULL; // 输入文件的demux// 打开文件&＃xff0c;主要是探测协议类型&＃xff0c;如果是网络文件则创建网络链接int ret &＃61; avformat_open_input(&ifmt_ctx, ifilename, NULL, NULL);if (ret <0) {char buf[1024] &＃61; {0};av_strerror(ret, buf, sizeof (buf) - 1);printf("open %s failed: %s\n", ifilename, buf);return -1;}// 2. 读取码流信息ret &＃61; avformat_find_stream_info(ifmt_ctx, NULL);if (ret <0) //如果打开媒体文件失败&＃xff0c;打印失败原因{char buf[1024] &＃61; { 0 };av_strerror(ret, buf, sizeof(buf) - 1);printf("avformat_find_stream_info %s failed:%s\n", ifilename, buf);avformat_close_input(&ifmt_ctx);return -1;}// 3.打印总体信息printf_s("\n&＃61;&＃61;&＃61;&＃61; av_dump_format in_filename:%s &＃61;&＃61;&＃61;\n", ifilename);av_dump_format(ifmt_ctx, 0, ifilename, 0);printf_s("\n&＃61;&＃61;&＃61;&＃61; av_dump_format finish &＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;\n\n");printf("media name:%s\n", ifmt_ctx->url);printf("stream number:%d\n", ifmt_ctx->nb_streams); // nb_streams媒体流数量printf("media average ratio:%lldkbps\n",(int64_t)(ifmt_ctx->bit_rate/1024)); // 媒体文件的码率,单位为bps// duration: 媒体文件时长&＃xff0c;单位微妙int total_seconds &＃61; (ifmt_ctx->duration) / AV_TIME_BASE; // 1000us &＃61; 1ms, 1000ms &＃61; 1秒printf("audio duration: %02d:%02d:%02d\n",total_seconds / 3600, (total_seconds % 3600) / 60, (total_seconds % 60));printf("\n");// 4.读取码流信息// 音频int audioindex &＃61; av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);if (audioindex <0) {printf("av_find_best_stream %s eror.", av_get_media_type_string(AVMEDIA_TYPE_AUDIO));return -1;}AVStream *audio_stream &＃61; ifmt_ctx->streams[audioindex];printf("----- Audio info:\n");printf("index: %d\n", audio_stream->index); // 序列号printf("samplarate: %d Hz\n", audio_stream->codecpar->sample_rate); // 采样率printf("sampleformat: %d\n", audio_stream->codecpar->format); // 采样格式 AV_SAMPLE_FMT_FLTP:8printf("audio codec: %d\n", audio_stream->codecpar->codec_id); // 编码格式 AV_CODEC_ID_MP3:86017 AV_CODEC_ID_AAC:86018if (audio_stream->duration !&＃61; AV_NOPTS_VALUE) {int audio_duration &＃61; audio_stream->duration * av_q2d(audio_stream->time_base);printf("audio duration: %02d:%02d:%02d\n",audio_duration / 3600, (audio_duration % 3600) / 60, (audio_duration % 60));}// 视频int videoindex &＃61; av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);if (videoindex <0) {printf("av_find_best_stream %s eror.", av_get_media_type_string(AVMEDIA_TYPE_VIDEO));return -1;}AVStream *video_stream &＃61; ifmt_ctx->streams[videoindex];printf("----- Video info:\n");printf("index: %d\n", video_stream->index); // 序列号printf("fps: %lf\n", av_q2d(video_stream->avg_frame_rate)); // 帧率printf("width: %d, height:%d \n", video_stream->codecpar->width, video_stream->codecpar->height);printf("video codec: %d\n", video_stream->codecpar->codec_id); // 编码格式 AV_CODEC_ID_H264: 27if (video_stream->duration !&＃61; AV_NOPTS_VALUE) {int video_duration &＃61; video_stream->duration * av_q2d(video_stream->time_base);printf("audio duration: %02d:%02d:%02d\n",video_duration / 3600, (video_duration % 3600) / 60, (video_duration % 60));}// 5.提取码流AVPacket *pkt &＃61; av_packet_alloc();int pkt_count &＃61; 0;int print_max_count &＃61; 10;printf("\n-----av_read_frame start\n");while (1){ret &＃61; av_read_frame(ifmt_ctx, pkt);if (ret <0) {printf("av_read_frame end\n");break;}if(pkt_count&＃43;&＃43; stream_index &＃61;&＃61; 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 &＃61;&＃61; 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);}// 6.结束if(pkt)av_packet_free(&pkt);if(ifmt_ctx)avformat_close_input(&ifmt_ctx);getchar(); //加上这一句&＃xff0c;防止程序打印完信息马上退出return 0;
}

输出&＃xff1a;

in_filename &＃61; believe.flv&＃61;&＃61;&＃61;&＃61; av_dump_format in_filename:believe.flv &＃61;&＃61;&＃61;
Input #0, flv, from &＃39;believe.flv&＃39;:Metadata:major_brand : isomminor_version : 512compatible_brands: isomiso2avc1mp41comment : www.ieway.cnencoder : Lavf58.29.100Duration: 00:03:42.53, start: 0.000000, bitrate: 286 kb/sStream #0:0: Video: h264 (Constrained Baseline), yuv420p(progressive), 1920x1080, 150 kb/s, 14.46 fps, 15 tbr, 1k tbn, 30 tbcStream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s&＃61;&＃61;&＃61;&＃61; av_dump_format finish &＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;media name:believe.flv
stream number:2
media average ratio:279kbps
audio duration: 00:03:42----- Audio info:
index: 1
samplarate: 48000 Hz
sampleformat: 8
audio codec: 86018
----- Video info:
index: 0
fps: 14.464286
width: 1920, height:1080
video codec: 27-----av_read_frame start
audio pts: 0
audio dts: 0
audio size: 341
audio pos: 502
audio duration: 0.021000video pts: 14
video dts: 14
video size: 66736
video pos: 860
video duration: 0.066000audio pts: 21
audio dts: 21
audio size: 341
audio pos: 67616
audio duration: 0.021000audio pts: 43
audio dts: 43
audio size: 342
audio pos: 67974
audio duration: 0.021000audio pts: 64
audio dts: 64
audio size: 341
audio pos: 68333
audio duration: 0.021000video pts: 81
video dts: 81
video size: 580
video pos: 68691
video duration: 0.066000audio pts: 85
audio dts: 85
audio size: 341
audio pos: 69291
audio duration: 0.021000audio pts: 107
audio dts: 107
audio size: 342
audio pos: 69649
audio duration: 0.021000audio pts: 128
audio dts: 128
audio size: 341
audio pos: 70008
audio duration: 0.021000video pts: 147
video dts: 147
video size: 11289
video pos: 70366
video duration: 0.066000av_read_frame end

https://www.cnblogs.com/vczf/p/13541559.html