C# 调用 FFmpeg 处理音视频

FFmpeg 开源、跨平台、体积小、功能强大，提供了录制、转换以及流化音视频的完整解决方案。

官网：https://www.ffmpeg.org/

百科：https://baike.baidu.com/item/ffmpeg/2665727?fr=aladdin

FFmpeg 应用非常广泛，可以用来播放本地视频甚至网络视频，查看音视频信息，还可以用于从视频中提取音频，转换音视频文件格式等等，本文主要介绍如何调用 FFmpeg 来查看音视频信息、从视频中提取音频、转换音视频格式等。

1. 调用FFmpeg

调用原理相当于打开控制台输入命令，只不过在程序中将命令参数进行组合封装，以下是启动代码：

        /// <summary>
        /// 初始化命令、参数，启动线程
        /// </summary>
        /// <param name="args"></param>
        /// <param name="finishiEvent"></param>
        public static void Start(string args, EventHandler finishiEvent)
        {
            LogHelper.LogInfoFormat("开始执行命令, 参数:{0}", args);
            FinishiEvent = finishiEvent;
            // ffmpeg.exe组件文件路径
            string ffmpegPath = FFmpegBinariesHelper.RegisterFFmpegBinaries();
            string cmdType = args.Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries)[0];
            ProcessStartInfo startInfo = new ProcessStartInfo(Path.Combine(ffmpegPath, cmdType));
            startInfo.WindowStyle = ProcessWindowStyle.Normal;
            startInfo.Arguments = args.Substring(cmdType.Length);
            startInfo.UseShellExecute = false;
            startInfo.CreateNoWindow = true;
            startInfo.RedirectStandardInput = true;
            startInfo.RedirectStandardOutput = true;
            startInfo.RedirectStandardError = true;// ffmpeg信息输出是error事件
            p.StartInfo = startInfo;
            p.OutputDataReceived += P_OutputDataReceived; // ffmpeg信息输出事件
            p.ErrorDataReceived += P_OutputDataReceived;
            Thread thread = new Thread(startffmpeg);
            thread.Start();
        }

运行界面：

2. 查看音视频信息

命令如下（注：pcm文件不适用以下命令）：

命令：ffprobe -print_format json -loglevel quiet -show_streams "您的文件"

示例：ffprobe -print_format json -loglevel quiet -show_streams "F:mp43.TF以及地图构建.mp4"

以下是输出的文件格式等信息：

{
    "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": "1046271/31388000",
            "codec_tag_string": "avc1",
            "codec_tag": "0x31637661",
            "width": 960,
            "height": 640,
            "coded_width": 960,
            "coded_height": 640,
            "has_b_frames": 0,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "3:2",
            "pix_fmt": "yuv420p",
            "level": 31,
            "chroma_location": "left",
            "refs": 1,
            "is_avc": "true",
            "nal_length_size": "4",
            "r_frame_rate": "15/1",
            "avg_frame_rate": "15694000/1046271",
            "time_base": "1/90000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 188328780,
            "duration": "2092.542000",
            "bit_rate": "358855",
            "bits_per_raw_sample": "8",
            "nb_frames": "31388",
            "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": {
                "creation_time": "2020-09-04T01:03:03.000000Z",
                "language": "und",
                "encoder": "JVT/AVC Coding"
            }
        },
        {
            "index": 1,
            "codec_name": "aac",
            "codec_long_name": "AAC (Advanced Audio Coding)",
            "profile": "LC",
            "codec_type": "audio",
            "codec_time_base": "1/48000",
            "codec_tag_string": "mp4a",
            "codec_tag": "0x6134706d",
            "sample_fmt": "fltp",
            "sample_rate": "48000",
            "channels": 1,
            "channel_layout": "mono",
            "bits_per_sample": 0,
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/48000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 100440014,
            "duration": "2092.500292",
            "bit_rate": "64000",
            "max_bit_rate": "66584",
            "nb_frames": "98086",
            "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": {
                "creation_time": "2020-09-04T01:03:03.000000Z",
                "language": "und"
            }
        }
    ]
}

 streams 输入信息，如果一个文件中有多个音频或视频，将以数组形式输出，常用参数有： codec_name 表示编码， codec_type 类型， sample_rate 采样率， channels 声道， duration 时长（秒）

 3.从视频中提取音频文件

命令：ffmpeg -i "您的视频文件路径" -vn -ar 采样率 "音频文件输出路径"

示例：ffmpeg -i "F:mp43.TF以及地图构建.mp4" -vn -ar 8000 "F:mp43.TF以及地图构建_201215172919_8k.m4a"

 以下是处理过程输出信息：

ffmpeg version git-2020-04-17-889ad93 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200328
  configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 42.102 / 56. 42.102
  libavcodec     58. 80.100 / 58. 80.100
  libavformat    58. 42.100 / 58. 42.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.101 /  7. 77.101
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'F:mp43.TF浠ュ強鍦板浘鏋勫缓.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    creation_time   : 2020-09-04T01:03:03.000000Z
  Duration: 00:34:52.54, start: 0.000000, bitrate: 425 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x640 [SAR 1:1 DAR 3:2], 358 kb/s, 15 fps, 15 tbr, 90k tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2020-09-04T01:03:03.000000Z
      encoder         : JVT/AVC Coding
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 64 kb/s (default)
    Metadata:
      creation_time   : 2020-09-04T01:03:03.000000Z
Stream mapping:
  Stream #0:1 -> #0:0 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[aac @ 042107c0] Too many bits 8832.000000 > 6144 per frame requested, clamping to max
Output #0, ipod, to 'F:mp43.TF浠ュ強鍦板浘鏋勫缓_201215172919_8k.m4a':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    encoder         : Lavf58.42.100
    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 48 kb/s (default)
    Metadata:
      creation_time   : 2020-09-04T01:03:03.000000Z
      encoder         : Lavc58.80.100 aac
size=     256kB time=00:01:42.40 bitrate=  20.5kbits/s speed= 204x    
size=     512kB time=00:03:28.64 bitrate=  20.1kbits/s speed= 208x    
size=     768kB time=00:05:12.19 bitrate=  20.2kbits/s speed= 208x    
size=    1280kB time=00:06:59.84 bitrate=  25.0kbits/s speed= 210x    
size=    1536kB time=00:08:38.52 bitrate=  24.3kbits/s speed= 207x    
size=    1792kB time=00:10:20.41 bitrate=  23.7kbits/s speed= 206x    
size=    2304kB time=00:12:11.77 bitrate=  25.8kbits/s speed= 209x    
size=    2560kB time=00:13:55.32 bitrate=  25.1kbits/s speed= 209x    
size=    2816kB time=00:15:40.41 bitrate=  24.5kbits/s speed= 209x    
size=    3072kB time=00:17:30.36 bitrate=  24.0kbits/s speed= 210x    
size=    3584kB time=00:19:17.12 bitrate=  25.4kbits/s speed= 210x    
size=    3840kB time=00:20:57.85 bitrate=  25.0kbits/s speed= 209x    
size=    4096kB time=00:22:44.73 bitrate=  24.6kbits/s speed= 210x    
size=    4608kB time=00:24:15.61 bitrate=  25.9kbits/s speed= 208x    
size=    4864kB time=00:25:52.63 bitrate=  25.7kbits/s speed= 207x    
size=    5120kB time=00:27:26.20 bitrate=  25.5kbits/s speed= 205x    
size=    5376kB time=00:29:04.38 bitrate=  25.2kbits/s speed= 205x    
size=    5632kB time=00:30:40.12 bitrate=  25.1kbits/s speed= 204x    
size=    6144kB time=00:32:20.47 bitrate=  25.9kbits/s speed= 204x    
size=    6400kB time=00:34:38.07 bitrate=  25.2kbits/s speed= 207x    
size=    6558kB time=00:34:52.54 bitrate=  25.7kbits/s speed= 209x    
video:0kB audio:6493kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.997352%
[aac @ 042107c0] Qavg: 65535.836

 4.转换音频格式：

命令：ffmpeg -i "源音频文件" -acodec pcm_s16le -f s16le -ar 目标音频采样率 "目标音频路径"

示例：ffmpeg -i "F:mp43.TF以及地图构建_201215172919_8k.m4a" -acodec pcm_s16le -f s16le -ar 8000 "F:mp43.TF以及地图构建_201215172919_8k_201215173520_8k.pcm"

处理过程输出信息：

ffmpeg version git-2020-04-17-889ad93 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200328
  configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 42.102 / 56. 42.102
  libavcodec     58. 80.100 / 58. 80.100
  libavformat    58. 42.100 / 58. 42.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.101 /  7. 77.101
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'F:mp43.TF浠ュ強鍦板浘鏋勫缓_201215172919_8k.m4a':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    encoder         : Lavf58.42.100
  Duration: 00:34:52.63, start: 0.000000, bitrate: 25 kb/s
    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 25 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, s16le, to 'F:mp43.TF浠ュ強鍦板浘鏋勫缓_201215172919_8k_201215173520_8k.pcm':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    encoder         : Lavf58.42.100
    Stream #0:0(und): Audio: pcm_s16le, 8000 Hz, mono, s16, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.80.100 pcm_s16le
size=   32696kB time=00:34:52.54 bitrate= 128.0kbits/s speed=8.63e+03x    
video:0kB audio:32696kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

5. 软件包下载（以上调用过程和参数已经封装处理，软件目的是调用百度音频识别API将视频中的音频转化为文字）

软件开源代码地址(项目集成文字识别、语音合成、语音识别)：https://gitee.com/bidev_admin/river-int-ai.git

运行软件包下载地址(.Net Framework 4.5)： https://pan.baidu.com/s/1z-WFDGHhEP8tqLqwp9I0Mw  提取码:  r3sk