ffmpeg系列：使用ffmpeg转换为RGB数据并缩放视频

来源：互联网发布：Linux 线程 sched_fifo 编辑：程序博客网时间：2024/05/16 16:11
main.cpp文件代码如下：
#include "myplayer.h"#include <QtWidgets/QApplication>#pragma comment(lib,"avformat.lib")#pragma comment(lib,"avutil.lib")#pragma comment(lib,"avcodec.lib")#pragma comment(lib,"swscale.lib")extern "C"{    #include <libavformat/avformat.h>    #include <libswscale/swscale.h>}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;SwsContext *cCtx = NULL;int outWidth = 640;int outHeight = 480;char *rgb = new char[outWidth * outHeight * 4];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]___");//打开ffmpeg格式转换和缩放器cCtx = sws_getCachedContext(cCtx, videoCtx->width, videoCtx->height, videoCtx->pix_fmt,outWidth, outHeight, AV_PIX_FMT_BGRA, SWS_BICUBIC,NULL, NULL, NULL);if (!cCtx){printf("sws_getCachedContext failed!\n");break;}uint8_t *data[AV_NUM_DATA_POINTERS] = {0};data[0] = (uint8_t *)rgb;int linesize[AV_NUM_DATA_POINTERS] = { 0 };linesize[0] = outWidth * 4;int h = sws_scale(cCtx, yuv->data, yuv->linesize, 0, videoCtx->height, data, linesize);if (h > 0){printf("(%d)", h);}printf("pts = %d 毫秒\n", pts);av_packet_unref(&pkt);}if (cCtx){sws_freeContext(cCtx);cCtx = NULL;}avformat_close_input(&ac);ac = NULL;QApplication a(argc, argv);MyPlayer w;w.show();return a.exec();}
运行结果如图：
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