-go is a Go for the . It to into their Go , such as and audio and video files, media , and and . -go a and API, it for Go to the of .

本质上-go是对命令行工具的封装，最终功能的实现都是通过在go里执行命令行工具来实现。

我们来看个例子。

在go代码中调用命令行工具。

// 包装ffprobe工具
// Probe Run ffprobe on the specified file and return a JSON representation of the output.
func Probe(fileName string, kwargs ...KwArgs) (string, error) {
	return ProbeWithTimeout(fileName, 0, MergeKwArgs(kwargs))
}
// 为命令行执行ffprobe增加timeout
func ProbeWithTimeout(fileName string, timeOut time.Duration, kwargs KwArgs) (string, error) {
	args := KwArgs{
		"show_format":  "",
		"show_streams": "",
		"of":           "json",
	}
	return ProbeWithTimeoutExec(fileName, timeOut, MergeKwArgs([]KwArgs{args, kwargs}))
}
// 生成ffprobe命令行执行用到的参数
func ProbeWithTimeoutExec(fileName string, timeOut time.Duration, kwargs KwArgs) (string, error) {
	args := ConvertKwargsToCmdLineArgs(kwargs)
	args = append(args, fileName)
	ctx := context.Background()
    // 将超时转换为context控制
	if timeOut > 0 {
		var cancel func()
		ctx, cancel = context.WithTimeout(context.Background(), timeOut)
		defer cancel()
	}
	cmd := exec.CommandContext(ctx, "ffprobe", args...)
	buf := bytes.NewBuffer(nil)
	stdErrBuf := bytes.NewBuffer(nil)
	cmd.Stdout = buf
	cmd.Stderr = stdErrBuf
	for _, option := range GlobalCommandOptions {
		option(cmd)
	}
    // 运行命令行的命令
    // 实际运行的是: ffprobe -of json -show_format -show_streams ${fileName}
	err := cmd.Run()
	if err != nil {
		return "", fmt.Errorf("[%s] %w", string(stdErrBuf.Bytes()), err)
	}
	return string(buf.Bytes()), nil
}

输出示例：

 "streams": [
                {
                    "index": 0,
                    "codec_name": "h264",
                    "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
                    "profile": "Main",
                    "codec_type": "video",
                    "codec_tag_string": "avc1",
                    "codec_tag": "0x31637661",
                    "width": 320,
                    "height": 240,
                    "coded_width": 320,
                    "coded_height": 240,
                    "closed_captions": 0,
                    "film_grain": 0,
                    "has_b_frames": 0,
                    "sample_aspect_ratio": "1:1",
                    "display_aspect_ratio": "4:3",
                    "pix_fmt": "yuv420p",
                    "level": 13,
                    "chroma_location": "left",
                    "field_order": "progressive",
                    "refs": 1,
                    "is_avc": "true",
                    "nal_length_size": "4",
                    "id": "0x1",
                    "r_frame_rate": "30000/1001",
                    "avg_frame_rate": "30000/1001",
                    "time_base": "1/90000",
                    "start_pts": 0,
                    "start_time": "0.000000",
                    "duration_ts": 627627,
                    "duration": "6.973633",
                    "bit_rate": "251413",
                    "bits_per_raw_sample": "8",
                    "nb_frames": "209",
                    "extradata_size": 37,
                    "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,
                        "captions": 0,
                        "descriptions": 0,
                        "metadata": 0,
                        "dependent": 0,
                        "still_image": 0
                    },
                    "tags": {
                        "language": "und",
                        "handler_name": "VideoHandler",
                        "vendor_id": "[0][0][0][0]"
                    }
                },
                {
                    "index": 1,
                    "codec_name": "aac",
                    "codec_long_name": "AAC (Advanced Audio Coding)",
                    "profile": "LC",
                    "codec_type": "audio",
                    "codec_tag_string": "mp4a",
                    "codec_tag": "0x6134706d",
                    "sample_fmt": "fltp",
                    "sample_rate": "44100",
                    "channels": 2,
                    "channel_layout": "stereo",
                    "bits_per_sample": 0,
                    "initial_padding": 0,
                    "id": "0x2",
                    "r_frame_rate": "0/0",
                    "avg_frame_rate": "0/0",
                    "time_base": "1/44100",
                    "start_pts": 0,
                    "start_time": "0.000000",
                    "duration_ts": 310272,
                    "duration": "7.035646",
                    "bit_rate": "125587",
                    "nb_frames": "303",
                    "extradata_size": 2,
                    "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,
                        "captions": 0,
                        "descriptions": 0,
                        "metadata": 0,
                        "dependent": 0,
                        "still_image": 0
                    },
                    "tags": {
                        "language": "und",
                        "handler_name": "SoundHandler",
                        "vendor_id": "[0][0][0][0]"
                    }
                }
            ],
            "format": {
                "filename": "./examples/sample_data/in1.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": "7.035646",
                "size": "336833",
                "bit_rate": "383001",
                "probe_score": 100,
                "tags": {
                    "major_brand": "isom",
                    "minor_version": "512",
                    "compatible_brands": "isomiso2avc1mp41",
                    "encoder": "Lavf57.71.100"
                }
            }
        }