FFmpeg学习：复用器的使用（录制摄像头和麦克风数据，输出mkv文件）

介绍

本文在上一篇复用器的使用基础上，将输入文件改为摄像头和麦克风

• 目前只是单线程

代码如下：

点击查看代码

#include <iostream>
#define __STDC_CONSTANT_MACROS //它允许C++程序使用C99标准中指定的 stdint.h 宏，而这些宏不在C++标准中。 
//诸如 UINT8_MAX ， INT64_MIN 和 INT32_C () 之类的宏可能已在C++应用程序中以其他方式定义

extern "C" {

#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/mathematics.h"
#include "libavutil/pixdesc.h"
#include "libavutil/imgutils.h"
#include "libavutil/dict.h"
#include "libavutil/parseutils.h"
#include "libavutil/samplefmt.h"
#include "libavutil/avassert.h"
#include "libavutil/time.h"
#include "libavformat/avformat.h"
#include "libavdevice/avdevice.h"
#include "libswscale/swscale.h"
#include "libavutil/opt.h"
#include "libavcodec/avfft.h"
#include "libswresample/swresample.h"

#define SDL_MAIN_HANDLED
#include "SDL.h"
#include "SDL_main.h"
#include "SDL_video.h"
#include "SDL_thread.h"
#if CONFIG_AVFILTER
# include "libavfilter/avfilter.h"
# include "libavfilter/buffersink.h"
# include "libavfilter/buffersrc.h"
#endif
}

#include <string>
int main()
{
	AVOutputFormat* OFormat = NULL;
	AVFormatContext* pvFormatCtx = NULL;//保存视频数据
	AVFormatContext* paFormatCtx = NULL;//保存音频数据
	AVFormatContext* poFormatCtx = NULL;//输出数据上下文
	int videoindex = -1, audioindex = -1;
	int videoindex_out = -1, audioindex_out = -1;
	int64_t frame_index = 0;
	int64_t cur_pts_v = 0, cur_pts_a = 0;
	const char* out_filename = "shuchu.mkv";//输出文件 "rtp://127.0.0.1:1234";//
	const char* audio_filename = "audio.mp3";//输出文件
	const char* video_filename = "video.h264";//输出文件
	AVPacket* pkt;
	int ret, i;

	pvFormatCtx = avformat_alloc_context();
	paFormatCtx = avformat_alloc_context();
	//poFormatCtx = avformat_alloc_context();
	//设备初始化
	avdevice_register_all();
	//网络初始化
	avformat_network_init();

	//打开摄像头——视频流	
	AVInputFormat* ifmt = av_find_input_format("dshow");
	AVDictionary* opt_v = NULL;
	av_dict_set(&opt_v, "rtbufsize", "100*1280*720", 0);//设置循环缓冲区大小
	av_dict_set(&opt_v, "video_size", "1280x720", 0);
	av_dict_set(&opt_v, "framerate", "30", 0);
	av_dict_set(&opt_v, "vcodec", "libx264", 0);//指定视频编码格式
	av_dict_set(&opt_v, "reuse", "1", 0);
	if (avformat_open_input(&pvFormatCtx, "video=Integrated Camera", ifmt, &opt_v) != 0) {
//	if (avformat_open_input(&pvFormatCtx, video_filename, NULL, NULL) != 0) {
		printf("Couldn't open video input stream.\n");
		return -1;
	}

	if (avformat_find_stream_info(pvFormatCtx, NULL) < 0)
	{
		printf("Couldn't find stream information.\n");
		return -1;
	}

	//打开麦克风——音频流
	AVDictionary* opt_a = NULL;
	av_dict_set(&opt_a, "acodec", "libfdk_aac",0);//指定音频编码格式
	//av_dict_set(&opt_v, "rtbufsize", "30*16*44100", 0);//设置循环缓冲区大小
	const char* audio_name = u8"audio=麦克风阵列 (英特尔® 智音技术)";//u8"audio=麦克风 (2- Realtek(R) Audio)";
	if (avformat_open_input(&paFormatCtx, audio_name, ifmt, &opt_a) != 0) {
//	if (avformat_open_input(&paFormatCtx, audio_filename, NULL, NULL) != 0) {
		printf("Couldn't open audio input stream.\n");
		return -1;
	}
	if (avformat_find_stream_info(paFormatCtx, NULL) < 0)
	{
		printf("Couldn't find stream information.\n");
		return -1;
	}
	
	//开始输出 rtp_mpegts(rtp支持的格式) mpegts(UDP支持的格式) flv(rtmp支持的格式)
	avformat_alloc_output_context2(&poFormatCtx, NULL, "rtp_mpegts", out_filename);//初始化输出文件
	if (!poFormatCtx) {
		printf("Could not create output context\n");
		return -1;
	}
	OFormat = poFormatCtx->oformat;

	//给输出添加视频流
	for (i = 0; i < pvFormatCtx->nb_streams; i++) {
		//Create output AVStream according to input AVStream
		if (pvFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
			/*
			* 步骤：
			* 1、首先根据视频流创建新的输出流（要添加初始化编码器）
			* 2、将原视频流的编码器上下文 复制 给输出流
			*/
			AVStream* in_stream = pvFormatCtx->streams[i];
			AVCodec* in_codec = avcodec_find_decoder(in_stream->codecpar->codec_id);
			AVStream* out_stream = avformat_new_stream(poFormatCtx, in_codec);
			videoindex = i;
			if (!out_stream) {
				printf("Failed allocating output stream\n");
				return -1;
			}
			videoindex_out = out_stream->index;
			//Copy the settings of AVCodecContext
			AVCodecContext* codec_ctx = avcodec_alloc_context3(in_codec);
			ret = avcodec_parameters_to_context(codec_ctx,in_stream->codecpar);
			if (ret < 0) {
				printf("Failed to copy in_stream codecpar to codec context\n");
				return -1;
			}
			codec_ctx->codec_tag = 0;
			if (poFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
				codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

			ret = avcodec_parameters_from_context(out_stream->codecpar, codec_ctx);
			if (ret < 0) {
				printf("Failed to copy codec context to out_stream codecpar context\n");
				return -1;
			}
		}
	}

	//给输出添加音频流
	for (i = 0; i < paFormatCtx->nb_streams; i++) {
		//Create output AVStream according to input AVStream
		if (paFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
			AVStream* in_stream = paFormatCtx->streams[i];
			AVCodec* in_codec = avcodec_find_decoder(in_stream->codecpar->codec_id);
			AVStream* out_stream = avformat_new_stream(poFormatCtx, in_codec);
			audioindex = i;
			if (!out_stream) {
				printf("Failed allocating output stream\n");
				return -1;
			}

			//av_copy_packet();
			audioindex_out = out_stream->index;
			//Copy the settings of AVCodecContext
			AVCodecContext* codec_ctx = avcodec_alloc_context3(in_codec);
			ret = avcodec_parameters_to_context(codec_ctx, in_stream->codecpar);
			if (ret < 0) {
				printf("Failed to copy in_stream codecpar to codec context\n");
				return -1;
			}
			codec_ctx->codec_tag = 0;
			if (poFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
				codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

			ret = avcodec_parameters_from_context(out_stream->codecpar, codec_ctx);
			if (ret < 0) {
				printf("Failed to copy codec context to out_stream codecpar context\n");
				return -1;
			}
		}
	}
	printf("==========Output Information==========\n");
	av_dump_format(poFormatCtx, 0, out_filename, 1);
	printf("======================================\n");
	//Open output file
	if (!(OFormat->flags & AVFMT_NOFILE)) {
		AVDictionary* dic = NULL;
		//av_dict_set(&dic, "vcodec", "copy", 0);//指定视频编码格式
		//av_dict_set(&dic, "pkt_size", "1316", 0);	//Maximum UDP packet size
		//av_dict_set(&dic, "fifo_size", "18800", 0);
		//av_dict_set(&dic, "buffer_size", "1000000", 0);
		//av_dict_set(&dic, "bitrate", "11000000", 0);
		//av_dict_set(&dic, "buffer_size", "1000000", 0);//1316
		//av_dict_set(&dic, "reuse", "1", 0);
		if (avio_open2(&poFormatCtx->pb, out_filename, AVIO_FLAG_WRITE, NULL, &dic) < 0) {
			printf("Could not open url '%s'", out_filename);
			return -1;
		}
	}
	//配置参数
	//av_opt_set(poFormatCtx->priv_data, "muxrate", "11000000", 0);
	//av_opt_set(poFormatCtx->priv_data, "MpegTSWrite", "1", 0);
	//av_opt_set(poFormatCtx->priv_data, "pes_payload_size", "300", 0);

	//Write file header	
	if (avformat_write_header(poFormatCtx, NULL) < 0) {
		printf("Error occurred when opening output file\n");
		return -1;
	}

	//开始写文件
	int64_t last_pts = -1;
	//start_time = av_gettime();

	AVPacket* pkta=NULL, * pktv=nullptr;
	while (1) {
		
		if (pktv == NULL) {
			pktv = av_packet_alloc();
			if (av_read_frame(pvFormatCtx, pktv) >= 0) {
				if (pktv->pts == AV_NOPTS_VALUE) {
					//Write PTS
					AVRational time_base1 = pvFormatCtx->streams[videoindex]->time_base;
					//Duration between 2 frames (us)
					int64_t calc_duration = (double)AV_TIME_BASE / av_q2d(pvFormatCtx->streams[videoindex]->r_frame_rate);
					//Parameters
					//pkt->pts = (double)(frame_index * calc_duration) / (double)(av_q2d(time_base1) * AV_TIME_BASE);
					pktv->pts = (double)((cur_pts_v+1) * calc_duration) / (double)(av_q2d(time_base1) * AV_TIME_BASE);
					pktv->dts = pktv->pts;
					pktv->duration = (double)calc_duration / (double)(av_q2d(time_base1) * AV_TIME_BASE);
				}
				cur_pts_v = pktv->pts;
			}
			else {
				av_packet_free(&pktv);
				break;
			}
		}
		if (pkta == NULL) {
			pkta = av_packet_alloc();
			if (av_read_frame(paFormatCtx, pkta) >= 0) {
				cur_pts_a = pkta->pts;
			}
			else {
				av_packet_free(&pkt);
				break;
			}
		}
		AVFormatContext* ifmt_ctx;
		int stream_index = 0;
		AVStream* in_stream, * out_stream;
		if (av_compare_ts(cur_pts_v, pvFormatCtx->streams[videoindex]->time_base, cur_pts_a, paFormatCtx->streams[audioindex]->time_base) <= 0) {
			ifmt_ctx = pvFormatCtx;
			stream_index = videoindex_out;

			in_stream = ifmt_ctx->streams[pktv->stream_index];
			out_stream = poFormatCtx->streams[stream_index];
			av_packet_rescale_ts(pktv,in_stream->time_base,out_stream->time_base);

			//
			if (last_pts >= pktv->pts) {
				pktv->pts = last_pts + 1;
				pktv->dts = last_pts + 1;
			}
			last_pts = pktv->pts;
			pktv->pos = -1;
			pktv->stream_index = stream_index;
			
			printf("frame_index: %lld Packet. in_video_pts: %lld Packet. size:%5d. pts:%lld\n", frame_index,cur_pts_v, pktv->size, pktv->pts);
			//Write
			if (av_interleaved_write_frame(poFormatCtx, pktv) < 0) {
				printf("Error muxing packet\n");
				break;
			}
			av_packet_free(&pktv);
			frame_index++;
		}
		else {
			ifmt_ctx = paFormatCtx;
			stream_index = audioindex_out;

			in_stream = ifmt_ctx->streams[pkta->stream_index];
			out_stream = poFormatCtx->streams[stream_index];
			av_packet_rescale_ts(pkta, in_stream->time_base, out_stream->time_base);

			if (last_pts >= pkta->pts) {
				pkta->pts = last_pts + 1;
				pkta->dts = last_pts + 1;
				
			}
			last_pts = pkta->pts;
			pkta->pos = -1;
			pkta->stream_index = stream_index;

			printf("frame_index: %lld Packet. in_audio_pts: %lld Packet. size:%5d. pts:%lld\n", frame_index, cur_pts_a, pkta->size, pkta->pts);
			//Write
			if (av_interleaved_write_frame(poFormatCtx, pkta) < 0) {
				printf("Error muxing packet\n");
				break;
			}
			av_packet_free(&pkta);
			frame_index++;
		}

		if (frame_index > 300) {
			break;
		}
	}
	//av_packet_free(&pkt);
	//Write file trailer
	av_write_trailer(poFormatCtx);

	avformat_close_input(&pvFormatCtx);
	avformat_close_input(&paFormatCtx);
	/* close output */
	if (poFormatCtx && !(OFormat->flags & AVFMT_NOFILE))
		avio_close(poFormatCtx->pb);
	avformat_free_context(poFormatCtx);
	if (ret < 0 && ret != AVERROR_EOF) {
		printf("Error occurred.\n");
		return -1;
	}
	
	return 0;
}

存在问题

已解决问题

【问题一：avformat_write_header时报错】

Could not find tag for codec pcm_s16le in stream #1, codec not currently supported in container 

解决方法：将输出的文件格式由mp4改为mkv；

【问题二：时间戳对不上】
自带播放器解码有问题，推荐使用 VLC。