ffmpeg编程查看视频文件信息

Bertha 。 2022-09-11 13:15 267阅读 0赞

# 效果如下 #

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5omL5pKV5Luj56CB5YWr55m-6YeM_size_20_color_FFFFFF_t_70_g_se_x_16]

# 执行效果打印日志 #

zh@zh-lpc:~/project/ffmpeg$ ./frmi  test.mp4
    open test.mp4 success.
    
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
      Metadata:
        major_brand     : isom
        minor_version   : 512
        compatible_brands: isomiso2avc1mp41
        title           : BigBuckBunny_115k.mov
        encoder         : Lavf58.76.100
      Duration: 00:05:52.96, bitrate: N/A
        Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 240x160, 87 kb/s, 23.88 fps, 24 tbr, 90k tbn (default)
        Metadata:
          handler_name    : VideoHandler
        Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 12000 Hz, 2 channels, 32 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
    zh@zh-lpc:~/project/ffmpeg$

# 简单分析 #

> 在真正实操之前，我们先来分析一下，我们正常使用C语言读取一个文件都需要哪些步骤：
> 
>  *  1、打开文件；
>  *  2、读取文件信息；
>  *  3、关闭文件。
> 
> 一般就是：open --> read --> close三步走。那么在ffmpeg中至少也需要这三步。

# Linux中原始读取文件的小实验 #

1、创建一个文件

zh@zh-lpc:~/project/unixapi$ echo  "aaaaa三生三世十里桃花123456" > info.txt

2、创建C语言编程文件

#include <stdio.h>
    #include <fcntl.h>
    
    #define BUFFSIZE 1024
    
    
    int main()
    { 
    
        int ret = 0;
        FILE *file;
        char buf[BUFFSIZE];
        char *fileName = "./info.txt";
    
        //open file
        file = fopen(fileName,"r");
    
        //read file
        fread(buf, BUFFSIZE+1, 1, file);
    
        printf("%s\n", buf);
    
        //close file
        fclose(file);
        
        return 0;
    }

3、编译

zh@zh-lpc:~/project/unixapi$ make unix_file
    cc     unix_file.c   -o unix_file
    zh@zh-lpc:~/project/unixapi$

4、执行

zh@zh-lpc:~/project/unixapi$ ./unix_file
    aaaaa三生三世十里桃花123456
    
    zh@zh-lpc:~/project/unixapi$

# ffmpeg读取视频文件信息—代码 #

ffmpeg\_read\_media\_info.c:

/** * use ffmpeg codeing read flow file info **/
    #include <stdio.h>
    #include <libavutil/log.h>
    #include <libavformat/avformat.h>
    
    int main(int argc, char *argv[])
    { 
        int ret = 0;
        const char* fileName = "";
        AVFormatContext *ac =  NULL;
        //set log level
        av_log_set_level(AV_LOG_INFO);
    
        //diff params = 2 is params != 2
        if(argc != 2)
        { 
            av_log(NULL,AV_LOG_WARNING,"params not enough. \n\n");
            return -1;
        }
    
        //file name 
        fileName = argv[1];
    
        //open video file
        ret = avformat_open_input(&ac,fileName,NULL,NULL);
    
        //diff open success or error
        if(ret < 0)
        { 
            av_log(NULL,AV_LOG_ERROR,"open %s error. \n\n",fileName);
            return -1;
        }else{ 
            av_log(NULL,AV_LOG_INFO,"open %s success. \n\n",fileName);
        }
    
        av_dump_format(ac,0,fileName,0);
    
        //close file flow
        avformat_close_input(&ac);
    
        return 0;    
    }

编译：

gcc -g -o frmi ffmpeg_read_media_info.c  -I/usr/local/ffmpeg/include -L/usr/local/ffmpeg/lib -lavformat -lavutil

执行

zh@zh-lpc:~/project/ffmpeg$ ls -l test.mp4
    -rwx------ 1 zh zh 5431627 9月  10 23:05 test.mp4
    zh@zh-lpc:~/project/ffmpeg$
    zh@zh-lpc:~/project/ffmpeg$ ls -l frmi
    -rwxrwxr-x 1 zh zh 65152 9月  16 22:00 frmi
    zh@zh-lpc:~/project/ffmpeg$
    zh@zh-lpc:~/project/ffmpeg$ ls -l ffmpeg_read_media_info.c
    -rwx------ 1 zh zh 955 9月  16 22:02 ffmpeg_read_media_info.c
    zh@zh-lpc:~/project/ffmpeg$
    zh@zh-lpc:~/project/ffmpeg$
    zh@zh-lpc:~/project/ffmpeg$ ./frmi test.mp4
    open test.mp4 success.
    
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
      Metadata:
        major_brand     : isom
        minor_version   : 512
        compatible_brands: isomiso2avc1mp41
        title           : BigBuckBunny_115k.mov
        encoder         : Lavf58.76.100
      Duration: 00:05:52.96, bitrate: N/A
        Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 240x160, 87 kb/s, 23.88 fps, 24 tbr, 90k tbn (default)
        Metadata:
          handler_name    : VideoHandler
        Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 12000 Hz, 2 channels, 32 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
    zh@zh-lpc:~/project/ffmpeg$

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