FFmpeg中拉取rtsp视频流并缩放显示测试代码

我会带着你远行 2021-12-09 22:27 558阅读 0赞

之前在[https://blog.csdn.net/fengbingchun/article/details/92198857][https_blog.csdn.net_fengbingchun_article_details_92198857]中给出过仅拉取rtsp视频流的测试代码，这里在此代码的基础上进行扩充，包括设置使用多线程进行解码，使用sws\_scale函数进行图像格式转换和缩放，并通过OpenCV进行显示，测试代码如下：

#include "funset.hpp"
    #include <iostream>
    
    #ifdef __cplusplus
    extern "C" {
    #endif
    
    #include <libavformat/avformat.h>
    #include <libswscale/swscale.h>
    #include <libavutil/imgutils.h>
    
    #ifdef __cplusplus
    }
    #endif
    
    #include <opencv2/opencv.hpp>
    #include "common.hpp"
    
    int test_ffmpeg_rtsp_client_decode_show()
    {
    	const char* url = "rtsp://184.72.239.149/vod/mp4://BigBuckBunny_115k.mov";
    	AVFormatContext* format_ctx = avformat_alloc_context();
    	int ret = avformat_open_input(&format_ctx, url, nullptr, nullptr);
    	if (ret != 0) {
    		fprintf(stderr, "fail to open url: %s, return value: %d\n", url, ret);
    		return -1;
    	}
    
    	ret = avformat_find_stream_info(format_ctx, nullptr);
    	if (ret < 0) {
    		fprintf(stderr, "fail to get stream information: %d\n", ret);
    		return -1;
    	}
    
    	int video_stream_index = -1, audio_stream_index = -1;
    	for (unsigned int i = 0; i < format_ctx->nb_streams; ++i) {
    		const AVStream* stream = format_ctx->streams[i];
    		if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
    			video_stream_index = i;
    			fprintf(stdout, "type of the encoded data: %d, dimensions of the video frame in pixels: width: %d, height: %d, pixel format: %d\n",
    				stream->codecpar->codec_id, stream->codecpar->width, stream->codecpar->height, stream->codecpar->format);
    		} else if (stream->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
    			audio_stream_index = i;
    			fprintf(stdout, "audio sample format: %d\n", stream->codecpar->format);
    		}
    	}
    
    	if (video_stream_index == -1) {
    		fprintf(stderr, "no video stream\n");
    		return -1;
    	}
    
    	if (audio_stream_index == -1) {
    		fprintf(stderr, "no audio stream\n");
    	}
    
    	AVCodecParameters* codecpar = format_ctx->streams[video_stream_index]->codecpar;
    	const AVCodec* codec = avcodec_find_decoder(codecpar->codec_id);
    	if (!codec) {
    		fprintf(stderr, "fail to avcodec_find_decoder\n");
    		return -1;
    	}
    
    	AVCodecContext* codec_ctx = avcodec_alloc_context3(codec);
    	if (!codec_ctx) {
    		fprintf(stderr, "fail to avcodec_alloc_context3\n");
    		return -1;
    	}
    
    	codec_ctx->pix_fmt = AVPixelFormat(codecpar->format);
    	codec_ctx->height = codecpar->height;
    	codec_ctx->width = codecpar->width;
    	codec_ctx->thread_count = 16;
    	ret = avcodec_open2(codec_ctx, codec, nullptr);
    	if (ret != 0) {
    		fprintf(stderr, "fail to avcodec_open2: %d\n", ret);
    		return -1;
    	}
    
    	const int width_new = 640, height_new = 480;
    	AVFrame* frame = av_frame_alloc();
    	AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
    	SwsContext* sws_ctx = sws_getContext(codec_ctx->width, codec_ctx->height, codec_ctx->pix_fmt, width_new, height_new, AV_PIX_FMT_BGR24, SWS_BICUBIC, nullptr, nullptr, nullptr);
    	if (!frame || !packet || !sws_ctx) {
    		fprintf(stderr, "fail to alloc\n");
    		return -1;
    	}
    
    	uint8_t* bgr_data[4];
    	int bgr_linesize[4];
    	av_image_alloc(bgr_data, bgr_linesize, width_new, height_new, AV_PIX_FMT_BGR24, 1);
    	cv::Mat mat(height_new, width_new, CV_8UC3);
    	const char* winname = "rtst video";
    	cv::namedWindow(winname);
    	long long time_begin, time_end;
    
    	while (1) {
    		//time_begin = Timer::getNowTime();
    		ret = av_read_frame(format_ctx, packet);
    		//time_end = Timer::getNowTime();
    		//fprintf(stdout, "av_read_frame cost time: %lldms\n", time_end - time_begin);
    		if (ret >= 0 && packet->stream_index == video_stream_index && packet->size > 0) {
    			//time_begin = Timer::getNowTime();
    			ret = avcodec_send_packet(codec_ctx, packet);
    			//time_end = Timer::getNowTime();
    			//fprintf(stdout, "avcodec_send_packet cost time: %lldms\n", time_end - time_begin);
    			if (ret < 0) {
    				fprintf(stderr, "##### fail to avcodec_send_packet: %d\n", ret);
    				av_packet_unref(packet);
    				continue;
    			}
    
    			//time_begin = Timer::getNowTime();
    			ret = avcodec_receive_frame(codec_ctx, frame);
    			//time_end = Timer::getNowTime();
    			//fprintf(stdout, "avcodec_receive_frame cost time: %lldms\n", time_end - time_begin);
    			if (ret < 0) {
    				fprintf(stderr, "##### fail to avcodec_receive_frame: %d\n", ret);
    				av_packet_unref(packet);
    				continue;
    			}
    
    			//time_begin = Timer::getNowTime();
    			sws_scale(sws_ctx, frame->data, frame->linesize, 0, codec_ctx->height, bgr_data, bgr_linesize);
    			//time_end = Timer::getNowTime();
    			//fprintf(stdout, "sws_scale cost time: %lldms\n", time_end - time_begin);
    			mat.data = bgr_data[0];
    			cv::imshow(winname, mat);
    		} else if (ret < 0 || packet->size <= 0) {
    			fprintf(stderr, "##### fail to av_read_frame: %d, packet size: %d\n", ret, packet->size);
    			continue;
    		}
    
    		av_packet_unref(packet);
    
    		int key = cv::waitKey(10);
    		if (key == 27) break;
    	}
    
    	cv::destroyWindow(winname);
    	av_frame_free(&frame);
    	sws_freeContext(sws_ctx);
    	avformat_close_input(&format_ctx);
    	av_freep(packet);
    	av_freep(&bgr_data[0]);
    
    	fprintf(stdout, "test finish\n");
    	return 0;
    }

执行结果如下：拉取到的rtsp视频流，编码类型为H264,像素格式为YUV420P，原始大小为240x160，通过sws\_scale将像素格式转换为bgr24并缩放到640x480显示。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlbmdiaW5nY2h1bg_size_16_color_FFFFFF_t_70][]

**GitHub**：[https://github.com/fengbingchun/OpenCV\_Test][https_github.com_fengbingchun_OpenCV_Test]

[https_blog.csdn.net_fengbingchun_article_details_92198857]: https://blog.csdn.net/fengbingchun/article/details/92198857
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlbmdiaW5nY2h1bg_size_16_color_FFFFFF_t_70]: /images/20211209/095ed4c53ff64090a57937bba69fbb7a.png
[https_github.com_fengbingchun_OpenCV_Test]: https://github.com/fengbingchun/OpenCV_Test