ffmpeg系列之两种视频解码方式

方式一：

#include "myplayer.h"
#include 
#pragma comment(lib,"avformat.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avcodec.lib")
extern "C"{
#include 
}
static double r2d(AVRational r){
	return r.num == 0 || r.den == 0 ? 0. : (double)r.num / (double)r.den;
}
int main(int argc, char *argv[])
{
	av_register_all();
	char *path = "test.mp4";
	AVFormatContext *ac = NULL;
	int re = avformat_open_input(&ac, path, 0, 0);
	
	if (re != 0){//打开文件失败
		char buf[1024] = { 0 };
		av_strerror(re, buf, sizeof(buf));
		printf("file %s open failed because of : %s", path, buf);
		getchar();
		return -1;
	}
	
	int totalSec = ac->duration / AV_TIME_BASE;
	printf("指定的视频文件有 %d分%d秒\n", totalSec / 60, totalSec % 60);

	int videoStream = 0;
	AVCodecContext *videoCtx = NULL;
	for (int i = 0; i < ac->nb_streams; i++)
	{
		AVCodecContext *enc = ac->streams[i]->codec;
		
		if (enc->codec_type == AVMEDIA_TYPE_VIDEO){
			videoStream = i;
			videoCtx = enc;
			AVCodec *codec = avcodec_find_decoder(enc->codec_id);
			if (!codec){
				printf("无法解码此视频文件\n");
				return -1;
			}
			int err = avcodec_open2(enc, codec, NULL);
			if (err != 0){
				char buf[1024] = { 0 };
				av_strerror(err, buf, sizeof(buf));
				printf(buf);
				return -2;
			}
			printf("\n");
			printf("成功打开视频编码流\n");
		}
	}
	AVFrame *yuv = av_frame_alloc();
	for (;;){
		AVPacket pkt;
		re = av_read_frame(ac, &pkt);
		if (re != 0){
			break;
		}
		if (pkt.stream_index != videoStream)
		{
			av_packet_unref(&pkt);
			continue;
		}
		int pts = pkt.pts * r2d(ac->streams[pkt.stream_index]->time_base) * 1000;//得到帧的毫秒值

		//=============================================================================
		int got_picture = 0;
		int re = avcodec_decode_video2(videoCtx,yuv,&got_picture,&pkt);
		if (got_picture){
			printf("[%d]___", re);
		}
		//=============================================================================

		printf("pts = %d 毫秒\n", pts);
		av_packet_unref(&pkt);
	}
	

	avformat_close_input(&ac);

	QApplication a(argc, argv);
	MyPlayer w;
	w.show();
	return a.exec();
}

运行结果：

第二种方式：

#include "myplayer.h"
#include 
#pragma comment(lib,"avformat.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avcodec.lib")
extern "C"{
#include 
}
static double r2d(AVRational r){
	return r.num == 0 || r.den == 0 ? 0. : (double)r.num / (double)r.den;
}
int main(int argc, char *argv[])
{
	av_register_all();
	char *path = "test.mp4";
	AVFormatContext *ac = NULL;
	int re = avformat_open_input(&ac, path, 0, 0);
	
	if (re != 0){//打开文件失败
		char buf[1024] = { 0 };
		av_strerror(re, buf, sizeof(buf));
		printf("file %s open failed because of : %s", path, buf);
		getchar();
		return -1;
	}
	
	int totalSec = ac->duration / AV_TIME_BASE;
	printf("指定的视频文件有 %d分%d秒\n", totalSec / 60, totalSec % 60);

	int videoStream = 0;
	AVCodecContext *videoCtx = NULL;
	for (int i = 0; i < ac->nb_streams; i++)
	{
		AVCodecContext *enc = ac->streams[i]->codec;
		
		if (enc->codec_type == AVMEDIA_TYPE_VIDEO){
			videoStream = i;
			videoCtx = enc;
			AVCodec *codec = avcodec_find_decoder(enc->codec_id);
			if (!codec){
				printf("无法解码此视频文件\n");
				return -1;
			}
			int err = avcodec_open2(enc, codec, NULL);
			if (err != 0){
				char buf[1024] = { 0 };
				av_strerror(err, buf, sizeof(buf));
				printf(buf);
				return -2;
			}
			printf("\n");
			printf("成功打开视频编码流\n");
		}
	}
	AVFrame *yuv = av_frame_alloc();
	for (;;){
		AVPacket pkt;
		re = av_read_frame(ac, &pkt);
		if (re != 0){
			break;
		}
		if (pkt.stream_index != videoStream)
		{
			av_packet_unref(&pkt);
			continue;
		}
		int pts = pkt.pts * r2d(ac->streams[pkt.stream_index]->time_base) * 1000;//得到帧的毫秒值

		//=============================================================================
		int re = avcodec_send_packet(videoCtx,&pkt);
		if (re != 0){
			av_packet_unref(&pkt);
			continue;
		}
		re = avcodec_receive_frame(videoCtx,yuv);
		if (re != 0){
			av_packet_unref(&pkt);
			continue;
		}
		printf("[D]___");
		//=============================================================================

		printf("pts = %d 毫秒\n", pts);
		av_packet_unref(&pkt);
	}
	

	avformat_close_input(&ac);

	QApplication a(argc, argv);
	MyPlayer w;
	w.show();
	return a.exec();
}

运行结果：