FFmpeg之ffprobe

   本文章内容局限于本人当前知识水平，如果有不当的地方或者更好的方法，欢迎大家批评指正。谢谢。 

FFmpeg是一套可以用来记录、转换数字音频、视频，并能将其转化为流的开源计算机程序。

其中目前我最常用的是ffmpeg，简直说是一个视频/图像领域十分强大的工具，值得CV处理领域的人深入学习。
再说ffprobe，最近正在做视频的手工特征提取，在提取比特率的时候遇到了意想不到的困难，查看一个视频的比特率十分简单，直接ffmpeg -i xxx.mp4就可以查看一个视频几乎所有的信息，当然opencv也可以查看视频的某一些信息，但是没有比特率，甚至你右击视频的属性也能可能到比特率。问题是，加上我需要处理数量十分庞大的视频，目前而前言我没有发现什么比较好的处理方法。经过一下午的思考（疯狂百度，疯狂Debug），找到了比较好的方案，在这里和大家分享一下，就用了ffporbe，ffprobe可以从多媒体流中收集信息，并且以人类和机器可读的方式进行输出，或者打印。
在使用之前需要先安装ffmpeg，具体安装方法可以找度娘，安装相对来说十分简单。我只讲一下自己暂时用到的，我这里在python中调用cmd，执行ffprobe命令，并且将cmd执行命令的结果以json的形式写出到文件。
代码如下：

 cmd = 'ffprobe -v quiet'                ' -print_format json'                ' -show_format '                '-show_streams '                'D:/DATA/{}.mp4 >>'                ' D:/DATA/{}_json.txt'.format(file_name,file_name)  os.popen(cmd)  #subprocess.call(cmd) 

这里要注意一下，不能用subprocess.call来执行cmd命令，因为最后会写不出文件，用os.popen()则能正常写出，原因未知。写出文件的json格式如下（我全部贴出来了，大家只需要找自己用的到的参数即可，具体参数含义大家自行百度）：

{     "streams": [         {             "index": 0,             "codec_name": "h264",             "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",             "profile": "High",             "codec_type": "video",             "codec_time_base": "1201/72000",             "codec_tag_string": "avc1",             "codec_tag": "0x31637661",             "width": 1920,             "height": 1080,             "coded_width": 1920,             "coded_height": 1088,             "closed_captions": 0,             "has_b_frames": 0,             "pix_fmt": "yuv420p",             "level": 41,             "color_range": "tv",             "color_space": "bt709",             "color_transfer": "bt709",             "color_primaries": "bt709",             "chroma_location": "left",             "refs": 1,             "is_avc": "true",             "nal_length_size": "4",             "r_frame_rate": "30000/1001",             "avg_frame_rate": "36000/1201",             "time_base": "1/19200",             "start_pts": 0,             "start_time": "0.000000",             "duration_ts": 192160,             "duration": "10.008333",             "bit_rate": "16753618",             "bits_per_raw_sample": "8",             "nb_frames": "300",             "disposition": {                 "default": 1,                 "dub": 0,                 "original": 0,                 "comment": 0,                 "lyrics": 0,                 "karaoke": 0,                 "forced": 0,                 "hearing_impaired": 0,                 "visual_impaired": 0,                 "clean_effects": 0,                 "attached_pic": 0,                 "timed_thumbnails": 0             },             "tags": {                 "language": "und",                 "handler_name": "VideoHandler"             }         },         {             "index": 1,             "codec_name": "aac",             "codec_long_name": "AAC (Advanced Audio Coding)",             "profile": "LC",             "codec_type": "audio",             "codec_time_base": "1/44100",             "codec_tag_string": "mp4a",             "codec_tag": "0x6134706d",             "sample_fmt": "fltp",             "sample_rate": "44100",             "channels": 1,             "channel_layout": "mono",             "bits_per_sample": 0,             "r_frame_rate": "0/0",             "avg_frame_rate": "0/0",             "time_base": "1/44100",             "start_pts": 0,             "start_time": "0.000000",             "duration_ts": 441344,             "duration": "10.007800",             "bit_rate": "62856",             "max_bit_rate": "63469",             "nb_frames": "431",             "disposition": {                 "default": 1,                 "dub": 0,                 "original": 0,                 "comment": 0,                 "lyrics": 0,                 "karaoke": 0,                 "forced": 0,                 "hearing_impaired": 0,                 "visual_impaired": 0,                 "clean_effects": 0,                 "attached_pic": 0,                 "timed_thumbnails": 0             },             "tags": {                 "language": "und",                 "handler_name": "SoundHandler"             }         }     ],     "format": {         "filename": "D:/DATA/A007.mp4",         "nb_streams": 2,         "nb_programs": 0,         "format_name": "mov,mp4,m4a,3gp,3g2,mj2",         "format_long_name": "QuickTime / MOV",         "start_time": "0.000000",         "duration": "10.009000",         "size": "21047968",         "bit_rate": "16823233",         "probe_score": 100,         "tags": {             "major_brand": "isom",             "minor_version": "512",             "compatible_brands": "isomiso2avc1mp41",             "encoder": "Lavf57.58.102"         }     } } {     "streams": [         {             "index": 0,             "codec_name": "h264",             "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",             "profile": "High",             "codec_type": "video",             "codec_time_base": "1201/72000",             "codec_tag_string": "avc1",             "codec_tag": "0x31637661",             "width": 1920,             "height": 1080,             "coded_width": 1920,             "coded_height": 1088,             "closed_captions": 0,             "has_b_frames": 0,             "pix_fmt": "yuv420p",             "level": 41,             "color_range": "tv",             "color_space": "bt709",             "color_transfer": "bt709",             "color_primaries": "bt709",             "chroma_location": "left",             "refs": 1,             "is_avc": "true",             "nal_length_size": "4",             "r_frame_rate": "30000/1001",             "avg_frame_rate": "36000/1201",             "time_base": "1/19200",             "start_pts": 0,             "start_time": "0.000000",             "duration_ts": 192160,             "duration": "10.008333",             "bit_rate": "16753618",             "bits_per_raw_sample": "8",             "nb_frames": "300",             "disposition": {                 "default": 1,                 "dub": 0,                 "original": 0,                 "comment": 0,                 "lyrics": 0,                 "karaoke": 0,                 "forced": 0,                 "hearing_impaired": 0,                 "visual_impaired": 0,                 "clean_effects": 0,                 "attached_pic": 0,                 "timed_thumbnails": 0             },             "tags": {                 "language": "und",                 "handler_name": "VideoHandler"             }         },         {             "index": 1,             "codec_name": "aac",             "codec_long_name": "AAC (Advanced Audio Coding)",             "profile": "LC",             "codec_type": "audio",             "codec_time_base": "1/44100",             "codec_tag_string": "mp4a",             "codec_tag": "0x6134706d",             "sample_fmt": "fltp",             "sample_rate": "44100",             "channels": 1,             "channel_layout": "mono",             "bits_per_sample": 0,             "r_frame_rate": "0/0",             "avg_frame_rate": "0/0",             "time_base": "1/44100",             "start_pts": 0,             "start_time": "0.000000",             "duration_ts": 441344,             "duration": "10.007800",             "bit_rate": "62856",             "max_bit_rate": "63469",             "nb_frames": "431",             "disposition": {                 "default": 1,                 "dub": 0,                 "original": 0,                 "comment": 0,                 "lyrics": 0,                 "karaoke": 0,                 "forced": 0,                 "hearing_impaired": 0,                 "visual_impaired": 0,                 "clean_effects": 0,                 "attached_pic": 0,                 "timed_thumbnails": 0             },             "tags": {                 "language": "und",                 "handler_name": "SoundHandler"             }         }     ],     "format": {         "filename": "D:/DATA/A007.mp4",         "nb_streams": 2,         "nb_programs": 0,         "format_name": "mov,mp4,m4a,3gp,3g2,mj2",         "format_long_name": "QuickTime / MOV",         "start_time": "0.000000",         "duration": "10.009000",         "size": "21047968",         "bit_rate": "16823233",         "probe_score": 100,         "tags": {             "major_brand": "isom",             "minor_version": "512",             "compatible_brands": "isomiso2avc1mp41",             "encoder": "Lavf57.58.102"         }     } } 

差点忘记说了，因为出发点是批量处理对嘛，可以用opencv读取视频序列，for循环一下然后将写出的json格式的文件再读入，查找自己需要的视频参数。