解封装:如下图所示,就是将FLV、MKV、MP4等文件解封装为视频H.264或H.265压缩数据,音频MP3或AAC的压缩数据,下图为常用的基本操作。
ffmpeg使用解封装的基本流程如下:
在使用FFmpeg API之前,需要先注册API,然后才能使用API。当然,新版本ffmpeg库不需要再调用下面的方法。
av_register_all()
初始化网络配置
avformat_network_init
设置一些参数,如下图所示,设置了最大延迟、传输协议等参数。
//参数设置AVDictionary *opts = NULL;//设置rtsp流已tcp协议打开av_dict_set(&opts, "rtsp_transport", "tcp", 0);av_dict_set(&opts, "max_delay", "500", 0);av_dict_set(&opts, "buffer_size", "1024000", 0);av_dict_set(&opts, "probsize", "4096", 0);av_dict_set(&opts, "fps", "25", 0);
构建AVFormatContext,声明输入的封装结构体,通过输入文件或者流地址作为封装结构的句柄。
AVFormatContext* inputFmtCtx = nullptr;const char* inputUrl = "test.mp4";///打开输入的流,获取数据 beginint ret = avformat_open_input(&inputFmtCtx, inputUrl, NULL, NULL);
查找音视频流信息,通过下面的接口与AVFormatContext中建立输入文件对应的流信息。
//查找;if (avformat_find_stream_info(inputFmtCtx, NULL) < 0){printf("Couldn't find stream information.\n");return false;}
读取音视频流,采用av_read_frame来读取数据包,读出来的数据存储在AVPacket中,确定其为音频、视频、字幕数据,最后解码,或者存储。
AVPacket* pkt = NULL;pkt = av_packet_alloc();while (av_read_frame(inputFmtCtx, pkt) >= 0){//获取数据包//.....解码或者存储//重置av_packet_unref(pkt);}
上述代码所示,通过循环调用av_read_frame()读取到pkt包,然后可以进行解码或者存储数据,如果读取的数据结束,则退出循环,开始指向结束操作。
每次使用完AVPacket包后,需要重置,否则会内存泄漏。
//重置av_packet_unref(pkt);
执行结束后关闭输入文件,释放资源。
//关闭avformat_close_input(&inputFmtCtx);//释放avformat_free_context(inputFmtCtx);//释放资源av_packet_free(&pkt);
新建空白解决方案,如下图所示。
解决方案,右键-添加-新建项目。
新建Qt控制台程序,3_demuxDemo
然后,配置ffmpeg的编译环境:看目录4。
ffmpeg环境配置
解封装源码示例:
#include <QtCore/QCoreApplication>extern "C" {
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/eval.h"
#include "libavutil/mathematics.h"
#include "libavutil/pixdesc.h"
#include "libavutil/imgutils.h"
#include "libavutil/dict.h"
#include "libavutil/fifo.h"
#include "libavutil/parseutils.h"
#include "libavutil/samplefmt.h"
#include "libavutil/time.h"
#include "libavutil/bprint.h"
#include "libavutil/opt.h"
#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"
#include "libavfilter/avfilter.h"
#include "libavdevice/avdevice.h"
#include "libswscale/swscale.h"
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "libavcodec/avfft.h"
#include "libswresample/swresample.h"
}#include <iostream>
using namespace std;static double r2d(AVRational r)
{return r.den == 0 ? 0 : (double)r.num / (double)r.den;
}int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);//av_register_all();avformat_network_init();AVDictionary* options = NULL;av_dict_set(&options, "buffer_size", "1024000", 0);av_dict_set(&options, "max_delay", "500000", 0);av_dict_set(&options, "stimeout", "2000000", 0);av_dict_set(&options, "rtsp_transport", "tcp", 0);AVFormatContext* inputFmtCtx = nullptr;const char* inputUrl = "F:/1920x1080.mp4";///打开输入的流,获取数据 beginint ret = avformat_open_input(&inputFmtCtx, inputUrl, NULL, NULL);if (ret != 0){printf("Couldn't open input stream.\n");return -1;}int vIndex = -1;int aIndex = -1;//查找;if (avformat_find_stream_info(inputFmtCtx, NULL) < 0){printf("Couldn't find stream information.\n");return false;}for (int i = 0; i < inputFmtCtx->nb_streams/*视音频流的个数*/; i++){//查找视频if (inputFmtCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO){vIndex = i;}else if (inputFmtCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO){aIndex = i;}}//===================video=================//视频宽int width = inputFmtCtx->streams[vIndex]->codecpar->width;//视频高int height = inputFmtCtx->streams[vIndex]->codecpar->height;//视频总时长sint64_t m_totalTime = static_cast<double>(inputFmtCtx->duration) / AV_TIME_BASE;//获取帧率;int fps = r2d(inputFmtCtx->streams[vIndex]->avg_frame_rate);if (fps == 0){fps = 25;}int iHour, iMinute, iSecond, iTotalSeconds;//HH:MM:SS//打印结构体信息puts("AVFormatContext信息:");puts("---------------------------------------------");iTotalSeconds = (int)inputFmtCtx->duration/*微秒*/ / 1000000;iHour = iTotalSeconds / 3600;//小时iMinute = iTotalSeconds % 3600 / 60;//分钟iSecond = iTotalSeconds % 60;//秒printf("持续时间:%02d:%02d:%02d\n", iHour, iMinute, iSecond);printf("平均混合码率:%d kb/s\n", inputFmtCtx->bit_rate / 1000);printf("视音频个数:%d\n", inputFmtCtx->nb_streams);puts("---------------------------------------------");puts("AVInputFormat信息:");puts("---------------------------------------------");printf("封装格式名称:%s\n", inputFmtCtx->iformat->name);printf("封装格式长名称:%s\n", inputFmtCtx->iformat->long_name);printf("封装格式扩展名:%s\n", inputFmtCtx->iformat->extensions);printf("封装格式ID:%d\n", inputFmtCtx->iformat->raw_codec_id);puts("---------------------------------------------");puts("AVStream信息:");puts("---------------------------------------------");printf("视频流标识符:%d\n", inputFmtCtx->streams[vIndex]->index);printf("音频流标识符:%d\n", inputFmtCtx->streams[aIndex]->index);printf("视频流长度:%d微秒\n", inputFmtCtx->streams[vIndex]->duration);printf("音频流长度:%d微秒\n", inputFmtCtx->streams[aIndex]->duration);puts("---------------------------------------------");printf("视频时长:%d微秒\n", inputFmtCtx->streams[vIndex]->duration);printf("音频时长:%d微秒\n", inputFmtCtx->streams[aIndex]->duration);printf("视频宽:%d\n", inputFmtCtx->streams[vIndex]->codecpar->width);printf("视频高:%d\n", inputFmtCtx->streams[vIndex]->codecpar->height);printf("音频采样率:%d\n", inputFmtCtx->streams[aIndex]->codecpar->sample_rate);printf("音频信道数目:%d\n", inputFmtCtx->streams[aIndex]->codecpar->channels);puts("AVFormatContext元数据:");puts("---------------------------------------------");AVDictionaryEntry *dict = NULL;while (dict = av_dict_get(inputFmtCtx->metadata, "", dict, AV_DICT_IGNORE_SUFFIX)){printf("[%s] = %s\n", dict->key, dict->value);}puts("---------------------------------------------");puts("AVStream视频元数据:");puts("---------------------------------------------");dict = NULL;while (dict = av_dict_get(inputFmtCtx->streams[vIndex]->metadata, "", dict, AV_DICT_IGNORE_SUFFIX)){printf("[%s] = %s\n", dict->key, dict->value);}puts("---------------------------------------------");puts("AVStream音频元数据:");puts("---------------------------------------------");dict = NULL;while (dict = av_dict_get(inputFmtCtx->streams[aIndex]->metadata, "", dict, AV_DICT_IGNORE_SUFFIX)){printf("[%s] = %s\n", dict->key, dict->value);}puts("---------------------------------------------");av_dump_format(inputFmtCtx, -1, inputUrl, 0);printf("\n\n编译信息:\n%s\n\n", avcodec_configuration());AVPacket* pkt = NULL;pkt = av_packet_alloc();while (av_read_frame(inputFmtCtx, pkt) >= 0){//获取数据包//.....解码或者存储//重置av_packet_unref(pkt);}//关闭avformat_close_input(&inputFmtCtx);//释放avformat_free_context(inputFmtCtx);//释放资源av_packet_free(&pkt);return a.exec();
}
运行截图:
完整工程:
https://download.csdn.net/download/wzz953200463/88959152https://download.csdn.net/download/wzz953200463/88959152