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h264文件不能直接在网页上播放,比如在浏览器上输入http://10.0.0.2/2022-01-08T22-32-58.h264,变成了下载。
若在浏览器上输入http://10.0.0.2/2022-01-08T22-32-58.mp4,则可以播放。
本文讲解用ffmpeg将h264文件转换成mp4。
首先,准备h264文件,这个可以用ffmpeg将一个mp4的视频部分转成h264,命令如下:
ffmpeg -i 2022-01-08T22-32-58.mp4 -an -vcodec copy 2022-01-08T22-32-58.h264
注意,我这里mp4里面的视频编码格式是h264,故用的vcodec copy,否则用vcodec libx264。
下面是将这个2022-01-08T22-32-58.h264封装成mp4,注意,没有解码编码过程,速度会很快。
大概过程如下:
1.启动两个线程
2.第一个线程av_read_frame读到packet,然后av_packet_clone拷贝出一个packet,塞入队列
3.第二个线程从队列中读取packet,进行pts,dts,duration设置,然后调用av_interleaved_write_frame写入。
这里面需要注意的地方在于pts,dts的设置,从ffmpeg源码上看,对于pts,dts的设置,也是很麻烦的,源码中,很多地方,动不动就看pts,dts是否需要设置。
本人之前采取下列方式进行dts和pts的设置,即由于读的context和写入的context的时间基(time_base)不一致,需要转换成目标文件context的时间基。
pPacketVideoA->dts = av_rescale_q_rnd(pPacketVideoA->dts, m_pFormatCtx_File->streams[m_iVideoIndex]->time_base, m_pFormatCtx_Out->streams[m_iVideoIndex]->time_base, AVRounding(1));
但实际运行时,出现了问题,读取出来的packet的pts和dts都是AV_NOPTS_VALUE,经过转换还是AV_NOPTS_VALUE,然后调用av_interleaved_write_frame出错。
最后调试ffmpeg源码,得到pts和dts的处理如下:
pPacketVideoA->duration = av_rescale_q_rnd(pPacketVideoA->duration, m_pFormatCtx_File->streams[m_iVideoIndex]->time_base, m_pFormatCtx_Out->streams[m_iVideoIndex]->time_base, AVRounding(1));
if (pPacketVideoA->dts != AV_NOPTS_VALUE)
{
pPacketVideoA->dts = av_rescale_q_rnd(pPacketVideoA->dts, m_pFormatCtx_File->streams[m_iVideoIndex]->time_base, m_pFormatCtx_Out->streams[m_iVideoIndex]->time_base, AVRounding(1));
pPacketVideoA->pts = pPacketVideoA->dts;
}
else
{
pPacketVideoA->pts = pPacketVideoA->dts = m_iTotalDuration;
}
m_iTotalDuration += pPacketVideoA->duration;
m_iTotalDuration的初始值,本人设置的是0,即第一帧的pts和dts都设置成0,下一帧的dts就是前面总帧的duration和,这个是ffmpeg里面的逻辑。
当然,ffmpeg里面判断复杂多了,比如参考了是否有B帧,本人所写的没考虑B帧,只考虑一个文件里面只有I帧,P帧的情况。
下面是代码结构
其中FfmpegH264ToMp4.cpp的内容如下:
// FfmpegH264ToMp4.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。 // #include <iostream> #include "H264ToMp4.h" int main() { CVideoConvert cVideoConvert; std::string strVideoFile = "2022-01-08T22-32-58.h264"; std::string strOutFile = "out.mp4"; cVideoConvert.StartConvert(strVideoFile, strOutFile); cVideoConvert.WaitFinish(); return 0; }
H264ToMp4.h里面的内容如下:
#pragma once #include <string> #include <Windows.h> #include <deque> #define MAX_VIDEOPACKET_NUM 100 #ifdef __cplusplus extern "C" { #endif #include "libavcodec/avcodec.h" #include "libavformat/avformat.h" #include "libswscale/swscale.h" #include "libswresample/swresample.h" #include "libavdevice/avdevice.h" #include "libavutil/audio_fifo.h" #include "libavutil/avutil.h" #include "libavutil/fifo.h" #include "libavutil/frame.h" #include "libavutil/imgutils.h" #include "libavfilter/avfilter.h" #include "libavfilter/buffersink.h" #include "libavfilter/buffersrc.h" #ifdef __cplusplus }; #endif class CVideoConvert { public: CVideoConvert(); ~CVideoConvert(); public: int StartConvert(std::string strFileName, std::string strFileOut); void StopConvert(); public: int OpenFile(const char *pFile); int OpenOutPut(const char *pFileOut); private: static DWORD WINAPI FileReadProc(LPVOID lpParam); void FileRead(); static DWORD WINAPI FileWriteProc(LPVOID lpParam); void FileWrite(); public: void WaitFinish(); public: AVFormatContext *m_pFormatCtx_File = NULL; AVFormatContext *m_pFormatCtx_Out = NULL; std::deque<AVPacket *> m_vecReadVideo; int m_iVideoWidth = 1920; int m_iVideoHeight = 1080; int m_iYuv420FrameSize = 0; int m_iVideoFrameNum = 0; int m_iVideoIndex = -1; bool m_bStartConvert = false; int64_t m_iTotalDuration = 0; private: CRITICAL_SECTION m_csVideoReadSection; HANDLE m_hFileReadThread = NULL; HANDLE m_hFileWriteThread = NULL; };
H264ToMp4.cpp里面的内容如下:
#include "H264ToMp4.h" #ifdef __cplusplus extern "C" { #endif #pragma comment(lib, "avcodec.lib") #pragma comment(lib, "avformat.lib") #pragma comment(lib, "avutil.lib") #pragma comment(lib, "avdevice.lib") #pragma comment(lib, "avfilter.lib") #pragma comment(lib, "postproc.lib") #pragma comment(lib, "swresample.lib") #pragma comment(lib, "swscale.lib") #ifdef __cplusplus }; #endif CVideoConvert::CVideoConvert() { InitializeCriticalSection(&m_csVideoReadSection); } CVideoConvert::~CVideoConvert() { DeleteCriticalSection(&m_csVideoReadSection); } int CVideoConvert::StartConvert(std::string strFileName, std::string strFileOut) { int ret = -1; do { ret = OpenFile(strFileName.c_str()); if (ret != 0) { break; } ret = OpenOutPut(strFileOut.c_str()); if (ret != 0) { break; } if (ret < 0) { break; } m_bStartConvert = true; m_hFileReadThread = CreateThread(NULL, 0, FileReadProc, this, 0, NULL); m_hFileWriteThread = CreateThread(NULL, 0, FileWriteProc, this, 0, NULL); } while (0); return ret; } void CVideoConvert::StopConvert() { m_bStartConvert = false; } int CVideoConvert::OpenFile(const char *pFile) { int ret = -1; do { if ((ret = avformat_open_input(&m_pFormatCtx_File, pFile, 0, 0)) < 0) { printf("Could not open input file."); break; } if ((ret = avformat_find_stream_info(m_pFormatCtx_File, 0)) < 0) { printf("Failed to retrieve input stream information"); break; } if (m_pFormatCtx_File->nb_streams > 2) { break; } for (int i = 0; i < m_pFormatCtx_File->nb_streams; i++) { if (m_pFormatCtx_File->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) { m_iVideoIndex = i; } } if (m_iVideoIndex == -1) { break; } ret = 0; } while (0); return ret; } int CVideoConvert::OpenOutPut(const char *pFileOut) { int iRet = -1; AVStream *pVideoStream = NULL; do { avformat_alloc_output_context2(&m_pFormatCtx_Out, NULL, NULL, pFileOut); if (m_iVideoIndex != -1) { AVCodecID eTargetVideoCodecId = m_pFormatCtx_File->streams[m_iVideoIndex]->codecpar->codec_id; AVCodec* pCodecEncode_Video = (AVCodec *)avcodec_find_encoder(eTargetVideoCodecId); pVideoStream = avformat_new_stream(m_pFormatCtx_Out, pCodecEncode_Video); if (!pVideoStream) { break; } avcodec_parameters_copy(pVideoStream->codecpar, m_pFormatCtx_File->streams[m_iVideoIndex]->codecpar); pVideoStream->codecpar->codec_tag = 0; } if (!(m_pFormatCtx_Out->oformat->flags & AVFMT_NOFILE)) { if (avio_open(&m_pFormatCtx_Out->pb, pFileOut, AVIO_FLAG_WRITE) < 0) { break; } } if (avformat_write_header(m_pFormatCtx_Out, NULL) < 0) { break; } iRet = 0; } while (0); if (iRet != 0) { if (m_pFormatCtx_Out != NULL) { avformat_free_context(m_pFormatCtx_Out); m_pFormatCtx_Out = NULL; } } return iRet; } DWORD WINAPI CVideoConvert::FileReadProc(LPVOID lpParam) { CVideoConvert *pVideoConvert = (CVideoConvert *)lpParam; if (pVideoConvert != NULL) { pVideoConvert->FileRead(); } return 0; } void CVideoConvert::FileRead() { AVPacket packet = { 0 }; int ret = 0; int iPicCount = 0; const int genpts = m_pFormatCtx_File->flags & AVFMT_FLAG_GENPTS; while (m_bStartConvert) { av_packet_unref(&packet); ret = av_read_frame(m_pFormatCtx_File, &packet); if (ret == AVERROR(EAGAIN)) { continue; } else if (ret == AVERROR_EOF) { break; } else if (ret < 0) { break; } if (packet.stream_index == m_iVideoIndex) { while (1) { int iAudioPacketNum = m_vecReadVideo.size(); if (iAudioPacketNum >= MAX_VIDEOPACKET_NUM) { Sleep(10); continue; } else { AVPacket *pAudioPacket = av_packet_clone(&packet); if (pAudioPacket != NULL) { EnterCriticalSection(&m_csVideoReadSection); m_vecReadVideo.push_back(pAudioPacket); LeaveCriticalSection(&m_csVideoReadSection); } } break; } } } //FlushVideoDecoder(iPicCount); } DWORD WINAPI CVideoConvert::FileWriteProc(LPVOID lpParam) { CVideoConvert *pVideoConvert = (CVideoConvert *)lpParam; if (pVideoConvert != NULL) { pVideoConvert->FileWrite(); } return 0; } void CVideoConvert::FileWrite() { int ret = 0; AVPacket packet = { 0 }; int iRealPicCount = 0; while (m_bStartConvert) { int iVideoSize = m_vecReadVideo.size(); if (iVideoSize > 0) { AVPacket *pPacketVideoA = NULL; EnterCriticalSection(&m_csVideoReadSection); if (!m_vecReadVideo.empty()) { pPacketVideoA = m_vecReadVideo.front(); m_vecReadVideo.pop_front(); } LeaveCriticalSection(&m_csVideoReadSection); pPacketVideoA->stream_index = m_iVideoIndex; pPacketVideoA->duration = av_rescale_q_rnd(pPacketVideoA->duration, m_pFormatCtx_File->streams[m_iVideoIndex]->time_base, m_pFormatCtx_Out->streams[m_iVideoIndex]->time_base, AVRounding(1)); if (pPacketVideoA->dts != AV_NOPTS_VALUE) { pPacketVideoA->dts = av_rescale_q_rnd(pPacketVideoA->dts, m_pFormatCtx_File->streams[m_iVideoIndex]->time_base, m_pFormatCtx_Out->streams[m_iVideoIndex]->time_base, AVRounding(1)); pPacketVideoA->pts = pPacketVideoA->dts; } else { pPacketVideoA->pts = pPacketVideoA->dts = m_iTotalDuration; } m_iTotalDuration += pPacketVideoA->duration; //ret = av_write_frame(m_pFormatCtx_Out, pPacketVideoA); ret = av_interleaved_write_frame(m_pFormatCtx_Out, pPacketVideoA); av_packet_free(&pPacketVideoA); if (ret == AVERROR(EAGAIN)) { continue; } else if (ret == AVERROR_EOF) { break; } iRealPicCount++; } else { Sleep(10); } } ///FlushEncoder(iRealPicCount); av_write_trailer(m_pFormatCtx_Out); avio_close(m_pFormatCtx_Out->pb); } void CVideoConvert::WaitFinish() { int ret = 0; do { if (NULL == m_hFileReadThread) { break; } WaitForSingleObject(m_hFileReadThread, INFINITE); CloseHandle(m_hFileReadThread); m_hFileReadThread = NULL; while (m_vecReadVideo.size() > 0) { Sleep(1000); } m_bStartConvert = false; WaitForSingleObject(m_hFileWriteThread, INFINITE); CloseHandle(m_hFileWriteThread); m_hFileWriteThread = NULL; } while (0); }
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