最簡單的基於FFmpeg的封裝格式處理 視音訊複用器 muxer
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最簡單的基於FFmpeg的封裝格式處理系列文章列表:
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簡介
打算記錄一下基於FFmpeg的封裝格式處理方面的例子。包括了視音訊分離,複用,封裝格式轉換。這是第3篇。
本文記錄一個基於FFmpeg的視音訊複用器(Simplest FFmpeg muxer)。視音訊複用器(Muxer)即是將視訊壓縮資料(例如H.264)和音訊壓縮資料(例如AAC)合併到一個封裝格式資料(例如MKV)中去。如圖所示。在這個過程中並不涉及到編碼和解碼。
流程
程式的流程如下圖所示。從流程圖中可以看出,一共初始化了3個AVFormatContext,其中2個用於輸入,1個用於輸出。3個AVFormatContext初始化之後,通過avcodec_copy_context()函式可以將輸入視訊/音訊的引數拷貝至輸出視訊/音訊的AVCodecContext結構體。然後分別呼叫視訊輸入流和音訊輸入流的av_read_frame(),從視訊輸入流中取出視訊的AVPacket,音訊輸入流中取出音訊的AVPacket,分別將取出的AVPacket寫入到輸出檔案中即可。其間用到了一個不太常見的函式av_compare_ts(),是比較時間戳用的。通過該函式可以決定該寫入視訊還是音訊。avformat_open_input():開啟輸入檔案。avcodec_copy_context():賦值AVCodecContext的引數。avformat_alloc_output_context2():初始化輸出檔案。avio_open():開啟輸出檔案。avformat_write_header():寫入檔案頭。av_compare_ts():比較時間戳,決定寫入視訊還是寫入音訊。這個函式相對要少見一些。av_read_frame():從輸入檔案讀取一個AVPacket。av_interleaved_write_frame():寫入一個AVPacket到輸出檔案。av_write_trailer():寫入檔案尾。
程式碼
下面貼上程式碼:
/** * 最簡單的基於FFmpeg的視音訊複用器 * Simplest FFmpeg Muxer * * 雷霄驊 Lei Xiaohua * [email protected] * 中國傳媒大學/數字電視技術 * Communication University of China / Digital TV Technology * http://blog.csdn.net/leixiaohua1020 * * 本程式可以將視訊碼流和音訊碼流打包到一種封裝格式中。 * 程式中將AAC編碼的音訊碼流和H.264編碼的視訊碼流打包成 * MPEG2TS封裝格式的檔案。 * 需要注意的是本程式並不改變視音訊的編碼格式。 * * This software mux a video bitstream and a audio bitstream * together into a file. * In this example, it mux a H.264 bitstream (in MPEG2TS) and * a AAC bitstream file together into MP4 format file. * */#include <stdio.h>#define __STDC_CONSTANT_MACROS#ifdef _WIN32//Windowsextern "C"{#include "libavformat/avformat.h"};#else//Linux...#ifdef __cplusplusextern "C"{#endif#include <libavformat/avformat.h>#ifdef __cplusplus};#endif#endif/*FIX: H.264 in some container format (FLV, MP4, MKV etc.) need "h264_mp4toannexb" bitstream filter (BSF) *Add SPS,PPS in front of IDR frame *Add start code ("0,0,0,1") in front of NALUH.264 in some container (MPEG2TS) don't need this BSF.*///'1': Use H.264 Bitstream Filter #define USE_H264BSF 0/*FIX:AAC in some container format (FLV, MP4, MKV etc.) need "aac_adtstoasc" bitstream filter (BSF)*///'1': Use AAC Bitstream Filter #define USE_AACBSF 0int main(int argc, char* argv[]){ AVOutputFormat *ofmt = NULL; //Input AVFormatContext and Output AVFormatContext AVFormatContext *ifmt_ctx_v = NULL, *ifmt_ctx_a = NULL,*ofmt_ctx = NULL; AVPacket pkt; int ret, i; int videoindex_v=-1,videoindex_out=-1; int audioindex_a=-1,audioindex_out=-1; int frame_index=0; int64_t cur_pts_v=0,cur_pts_a=0; //const char *in_filename_v = "cuc_ieschool.ts";//Input file URL const char *in_filename_v = "cuc_ieschool.h264"; //const char *in_filename_a = "cuc_ieschool.mp3"; //const char *in_filename_a = "gowest.m4a"; //const char *in_filename_a = "gowest.aac"; const char *in_filename_a = "huoyuanjia.mp3"; const char *out_filename = "cuc_ieschool.mp4";//Output file URL av_register_all(); //Input if ((ret = avformat_open_input(&ifmt_ctx_v, in_filename_v, 0, 0)) < 0) { printf( "Could not open input file."); goto end; } if ((ret = avformat_find_stream_info(ifmt_ctx_v, 0)) < 0) { printf( "Failed to retrieve input stream information"); goto end; } if ((ret = avformat_open_input(&ifmt_ctx_a, in_filename_a, 0, 0)) < 0) { printf( "Could not open input file."); goto end; } if ((ret = avformat_find_stream_info(ifmt_ctx_a, 0)) < 0) { printf( "Failed to retrieve input stream information"); goto end; } printf("===========Input Information==========\n"); av_dump_format(ifmt_ctx_v, 0, in_filename_v, 0); av_dump_format(ifmt_ctx_a, 0, in_filename_a, 0); printf("======================================\n"); //Output avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename); if (!ofmt_ctx) { printf( "Could not create output context\n"); ret = AVERROR_UNKNOWN; goto end; } ofmt = ofmt_ctx->oformat; for (i = 0; i < ifmt_ctx_v->nb_streams; i++) { //Create output AVStream according to input AVStream if(ifmt_ctx_v->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){ AVStream *in_stream = ifmt_ctx_v->streams[i]; AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec); videoindex_v=i; if (!out_stream) { printf( "Failed allocating output stream\n"); ret = AVERROR_UNKNOWN; goto end; } videoindex_out=out_stream->index; //Copy the settings of AVCodecContext if (avcodec_copy_context(out_stream->codec, in_stream->codec) < 0) { printf( "Failed to copy context from input to output stream codec context\n"); goto end; } out_stream->codec->codec_tag = 0; if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER; break; } } for (i = 0; i < ifmt_ctx_a->nb_streams; i++) { //Create output AVStream according to input AVStream if(ifmt_ctx_a->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){ AVStream *in_stream = ifmt_ctx_a->streams[i]; AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec); audioindex_a=i; if (!out_stream) { printf( "Failed allocating output stream\n"); ret = AVERROR_UNKNOWN; goto end; } audioindex_out=out_stream->index; //Copy the settings of AVCodecContext if (avcodec_copy_context(out_stream->codec, in_stream->codec) < 0) { printf( "Failed to copy context from input to output stream codec context\n"); goto end; } out_stream->codec->codec_tag = 0; if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER; break; } } printf("==========Output Information==========\n"); av_dump_format(ofmt_ctx, 0, out_filename, 1); printf("======================================\n"); //Open output file if (!(ofmt->flags & AVFMT_NOFILE)) { if (avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE) < 0) { printf( "Could not open output file '%s'", out_filename); goto end; } } //Write file header if (avformat_write_header(ofmt_ctx, NULL) < 0) { printf( "Error occurred when opening output file\n"); goto end; } //FIX#if USE_H264BSF AVBitStreamFilterContext* h264bsfc = av_bitstream_filter_init("h264_mp4toannexb"); #endif#if USE_AACBSF AVBitStreamFilterContext* aacbsfc = av_bitstream_filter_init("aac_adtstoasc"); #endif while (1) { AVFormatContext *ifmt_ctx; int stream_index=0; AVStream *in_stream, *out_stream; //Get an AVPacket if(av_compare_ts(cur_pts_v,ifmt_ctx_v->streams[videoindex_v]->time_base,cur_pts_a,ifmt_ctx_a->streams[audioindex_a]->time_base) <= 0){ ifmt_ctx=ifmt_ctx_v; stream_index=videoindex_out; if(av_read_frame(ifmt_ctx, &pkt) >= 0){ do{ in_stream = ifmt_ctx->streams[pkt.stream_index]; out_stream = ofmt_ctx->streams[stream_index]; if(pkt.stream_index==videoindex_v){ //FIX:No PTS (Example: Raw H.264) //Simple Write PTS if(pkt.pts==AV_NOPTS_VALUE){ //Write PTS AVRational time_base1=in_stream->time_base; //Duration between 2 frames (us) int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate); //Parameters pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE); pkt.dts=pkt.pts; pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE); frame_index++; } cur_pts_v=pkt.pts; break; } }while(av_read_frame(ifmt_ctx, &pkt) >= 0); }else{ break; } }else{ ifmt_ctx=ifmt_ctx_a; stream_index=audioindex_out; if(av_read_frame(ifmt_ctx, &pkt) >= 0){ do{ in_stream = ifmt_ctx->streams[pkt.stream_index]; out_stream = ofmt_ctx->streams[stream_index]; if(pkt.stream_index==audioindex_a){ //FIX:No PTS //Simple Write PTS if(pkt.pts==AV_NOPTS_VALUE){ //Write PTS AVRational time_base1=in_stream->time_base; //Duration between 2 frames (us) int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate); //Parameters pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE); pkt.dts=pkt.pts; pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE); frame_index++; } cur_pts_a=pkt.pts; break; } }while(av_read_frame(ifmt_ctx, &pkt) >= 0); }else{ break; } } //FIX:Bitstream Filter#if USE_H264BSF av_bitstream_filter_filter(h264bsfc, in_stream->codec, NULL, &pkt.data, &pkt.size, pkt.data, pkt.size, 0);#endif#if USE_AACBSF av_bitstream_filter_filter(aacbsfc, out_stream->codec, NULL, &pkt.data, &pkt.size, pkt.data, pkt.size, 0);#endif //Convert PTS/DTS pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX)); pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX)); pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base); pkt.pos = -1; pkt.stream_index=stream_index; printf("Write 1 Packet. size:%5d\tpts:%lld\n",pkt.size,pkt.pts); //Write if (av_interleaved_write_frame(ofmt_ctx, &pkt) < 0) { printf( "Error muxing packet\n"); break; } av_free_packet(&pkt); } //Write file trailer av_write_trailer(ofmt_ctx);#if USE_H264BSF av_bitstream_filter_close(h264bsfc);#endif#if USE_AACBSF av_bitstream_filter_close(aacbsfc);#endifend: avformat_close_input(&ifmt_ctx_v); avformat_close_input(&ifmt_ctx_a); /* close output */ if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE)) avio_close(ofmt_ctx->pb); avformat_free_context(ofmt_ctx); if (ret < 0 && ret != AVERROR_EOF) { printf( "Error occurred.\n"); return -1; } return 0;}
結果
輸入檔案為:視訊:cuc_ieschool.ts音訊:huoyuanjia.mp3
輸出檔案為:cuc_ieschool.mp4輸出的檔案視訊為“cuc_ieschool”,配合“霍元甲”的音訊。下載
simplest ffmpeg format
專案主頁
CSDN下載:工程中包含4個例子:
simplest_ffmpeg_demuxer_simple:視音訊分離器(簡化版)。
simplest_ffmpeg_demuxer:視音訊分離器。
simplest_ffmpeg_muxer:視音訊複用器。
simplest_ffmpeg_remuxer:封裝格式轉換器。
更新-1.1==================================================
修復了以下問題:
(1)Release版本下的執行問題
(2)simplest_ffmpeg_muxer封裝H.264裸流的時候丟失聲音的錯誤
關於simplest_ffmpeg_muxer封裝H.264裸流的時候丟失聲音的問題目前已經解決。根源在於H.264裸流沒有PTS,因此必須手動寫入PTS。寫入PTS的程式碼在在舊版本中已經包含:
//FIX:No PTS//Simple Write PTSif(pkt.pts==AV_NOPTS_VALUE){ //Write PTS AVRational time_base1=in_stream->time_base; //Duration between 2 frames (us) int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate); //Parameters pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE); pkt.dts=pkt.pts; pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE); frame_index++;}
但是舊版本中這段程式碼的位置放錯了,應該放在av_read_frame()之後,cur_pts_a/cur_pts_v賦值之前。換句話說,也就說要把這段程式碼“前移”。修改後問題解決。CSDN下載地址:
更新-1.2 (2015.2.13)=========================================
這次考慮到了跨平臺的要求,調整了原始碼。經過這次調整之後,原始碼可以在以下平臺編譯通過:
VC++:開啟sln檔案即可編譯,無需配置。
cl.exe:開啟compile_cl.bat即可命令列下使用cl.exe進行編譯,注意可能需要按照VC的安裝路徑調整腳本里面的引數。編譯命令如下。
::VS2010 Environmentcall "D:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"::[email protected] INCLUDE=include;%INCLUDE%::[email protected] LIB=lib;%LIB%::compile and linkcl simplest_ffmpeg_muxer.cpp /link avcodec.lib avformat.lib avutil.lib ^avdevice.lib avfilter.lib postproc.lib swresample.lib swscale.lib /OPT:NOREF
MinGW:MinGW命令列下執行compile_mingw.sh即可使用MinGW的g++進行編譯。編譯命令如下。
g++ simplest_ffmpeg_muxer.cpp -g -o simplest_ffmpeg_muxer.exe \-I /usr/local/include -L /usr/local/lib -lavformat -lavcodec -lavutil
GCC:Linux或者MacOS命令列下執行compile_gcc.sh即可使用GCC進行編譯。編譯命令如下。
gcc simplest_ffmpeg_muxer.cpp -g -o simplest_ffmpeg_muxer.out -I /usr/local/include -L /usr/local/lib \-lavformat -lavcodec -lavutil
PS:相關的編譯命令已經儲存到了工程資料夾中CSDN下載地址:http://download.csdn.net/detail/leixiaohua1020/8445303SourceForge上已經更新。