二、mp4转wmv项目讲解
2019-05-23 本文已影响0人
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本文用到的函数:
| 序号 | 函数名 | 参数 | 注释 |
|---|---|---|---|
| 1 | av_register_all | void av_register_all(void) | 注册所有的封装器和解封器 |
| 2 | avformat_open_input | int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options) | 创建一个输入的上下文环境 |
| 3 | avformat_alloc_output_context2 | int avformat_alloc_output_context2(AVFormatContext **ctx, AVOutputFormat *oformat,const char *format_name, const char *filename); | 创建一个输出的上下文环境 |
| 4 | avformat_new_stream | AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c) | 在指定上下文中插入一个Stream成员 |
| 5 | avcodec_parameters_copy | int avcodec_parameters_copy(AVCodecParameters *dst, const AVCodecParameters *src) | copyAVCodec的上下文 |
| 6 | avio_open | int avio_open(AVIOContext **s, const char *url, int flags) | 打开FFmpeg的输入输出文件 |
| 7 | avformat_write_header | int avformat_write_header(AVFormatContext *s, AVDictionary **options) | 写视频文件头 |
| 8 | av_read_frame | int av_read_frame(AVFormatContext *s, AVPacket *pkt) | 读入指定上下文的一帧 |
| 9 | av_rescale_q_rnd | int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,enum AVRounding rnd) | 换算比例 |
| 10 | av_write_frame | int av_write_frame(AVFormatContext *s, AVPacket *pkt) | 向指定上下文写入一帧 |
| 11 | av_packet_unref | void av_packet_unref(AVPacket *pkt) | 释放AVPacket内存 |
| 12 | av_write_trailer | int av_write_trailer(AVFormatContext *s) | 写视频文件尾 |
| 13 | avio_close | int avio_close(AVIOContext *s) | 关闭FFmpeg的输入输出文件 |
0001.jpg
#include <iostream>
extern "C" {
#include<libavformat/avformat.h>
#include<libavcodec/avcodec.h>
}
#pragma comment(lib,"avformat.lib")
#pragma comment(lib,"avcodec.lib")
#pragma comment(lib,"avutil.lib")
using namespace std;
int main()
{
char infile[] = "2.mp4";
char outfile[] = "output.mov";
av_register_all();//注册所有的封装器和解封器
AVFormatContext* inputFormatCtx = NULL;
avformat_open_input(&inputFormatCtx, infile, NULL, NULL);
if (!inputFormatCtx) {
printf("open file fail!\n");
return -1;
}
AVFormatContext* outputFormatCtx = NULL;
avformat_alloc_output_context2(&outputFormatCtx, NULL, NULL, outfile);
if (!outputFormatCtx){
printf("create OutputCtx fail!\n");
return -2;
}
AVStream *videoStream = avformat_new_stream(outputFormatCtx, NULL);
AVStream *audioStream= avformat_new_stream(outputFormatCtx, NULL);
avcodec_parameters_copy(videoStream->codecpar, inputFormatCtx->streams[0]->codecpar);
avcodec_parameters_copy(audioStream->codecpar, inputFormatCtx->streams[0]->codecpar);
videoStream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
audioStream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
av_dump_format(inputFormatCtx, 0, infile, 0);
printf("============================================");
av_dump_format(outputFormatCtx, 0, outfile, 1);
int ret=avio_open(&outputFormatCtx->pb, outfile, AVIO_FLAG_WRITE);
if (ret < 0) {
printf("avio open failed!\n");
return -3;
}
avformat_write_header(outputFormatCtx, NULL);
if (ret < 0)
{
printf("write header failed!\n");
}
AVPacket pkt;
int i = 0;
for (;;)
{
ret=av_read_frame(inputFormatCtx, &pkt);
if (ret < 0) {
break;
}
pkt.pts=av_rescale_q_rnd(pkt.pts,
inputFormatCtx->streams[pkt.stream_index]->time_base,
outputFormatCtx->streams[pkt.stream_index]->time_base,
(AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
pkt.dts=av_rescale_q_rnd(pkt.dts,
inputFormatCtx->streams[pkt.stream_index]->time_base,
outputFormatCtx->streams[pkt.stream_index]->time_base,
(AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
pkt.pos = -1;
pkt.duration= av_rescale_q_rnd(pkt.duration,
inputFormatCtx->streams[pkt.stream_index]->time_base,
outputFormatCtx->streams[pkt.stream_index]->time_base,
(AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
av_write_frame(outputFormatCtx, &pkt);
av_packet_unref(&pkt);
cout <<".";
}
cout << "\n=========================" << endl;
av_write_trailer(outputFormatCtx);
avio_close(outputFormatCtx->pb);
}
