使用OpenCV类库，从视频中截取视频帧

一、用途

用于构建日志报告，报告中中某软件运行的截图，有问题时，日志与视频当时的帧对应。

二、代码实现

using System;
using System.Reflection;
using OpenCvSharp;
using OpenCvSharp.Extensions;namespace PicInVideo
{/// <summary>/// 视频帧截取工具类（支持指定时间点截取）/// </summary>public static class VideoFrameCaptureTool{/// <summary>/// 从视频中截取指定时间点的帧/// </summary>/// <param name="videoPath">视频文件路径（支持FFmpeg录制的MP4/MKV/AVI等格式）</param>/// <param name="outputImagePath">输出图片路径（含文件名，如：D:\frame.jpg）</param>/// <param name="videoStartTime">视频开始的绝对时间（格式：yyyy-MM-dd HH:mm:ss）</param>/// <param name="targetCaptureTime">要截取的绝对时间（格式：yyyy-MM-dd HH:mm:ss）</param>/// <returns>是否截取成功</returns>public static bool CaptureFrameByAbsoluteTime(string videoPath,string outputImagePath,string videoStartTime,string targetCaptureTime){// 验证输入参数if (!File.Exists(videoPath)){throw new Exception($"错误：视频文件不存在 - {videoPath}");}// 解析时间戳if (!DateTime.TryParseExact(videoStartTime, "yyyy-MM-dd HH:mm:ss",System.Globalization.CultureInfo.InvariantCulture,System.Globalization.DateTimeStyles.None, out DateTime startDt)){//Console.WriteLine($"错误：视频开始时间格式无效（应为 yyyy-MM-dd HH:mm:ss） - {videoStartTime}");return false;}if (!DateTime.TryParseExact(targetCaptureTime, "yyyy-MM-dd HH:mm:ss",System.Globalization.CultureInfo.InvariantCulture,System.Globalization.DateTimeStyles.None, out DateTime targetDt)){//Console.WriteLine($"错误：目标截取时间格式无效（应为 yyyy-MM-dd HH:mm:ss） - {targetCaptureTime}");return false;}// 计算目标时间相对于视频开始的偏移秒数TimeSpan timeOffset = targetDt - startDt;if (timeOffset.TotalSeconds < 0){//Console.WriteLine("错误：目标截取时间早于视频开始时间");return false;}// 调用核心截取方法（按相对时间偏移）return CaptureFrameByRelativeTime(videoPath, outputImagePath, timeOffset.TotalSeconds);}/// <summary>/// 从视频中截取指定相对时间点的帧（相对于视频开始）/// </summary>/// <param name="videoPath">视频文件路径</param>/// <param name="outputImagePath">输出图片路径</param>/// <param name="relativeSeconds">相对于视频开始的偏移秒数（如：10.5 表示第10.5秒）</param>/// <returns>是否截取成功</returns>public static bool CaptureFrameByRelativeTime(string videoPath,string outputImagePath,double relativeSeconds){// 验证参数if (!File.Exists(videoPath)){throw new Exception($"错误：视频文件不存在 - {videoPath}");}if (relativeSeconds < 0){return false;}// 创建输出目录（如果需要）string outputDir = Path.GetDirectoryName(outputImagePath);if (!string.IsNullOrEmpty(outputDir) && !Directory.Exists(outputDir)){Directory.CreateDirectory(outputDir);}// 打开视频并定位到目标帧using (var capture = new VideoCapture(videoPath)){if (!capture.IsOpened()){//Console.WriteLine($"错误：无法打开视频文件 - {videoPath}");return false;}// 获取视频关键信息double fps = capture.Fps;int totalFrames = (int)capture.FrameCount;double totalSeconds = totalFrames / fps; // 视频总时长（秒）//Console.WriteLine($"视频信息：帧率={fps:F2} FPS，总帧数={totalFrames}，总时长={totalSeconds:F2}秒");//Console.WriteLine($"目标截取时间：相对视频开始 {relativeSeconds:F2} 秒");// 检查目标时间是否超出视频时长if (relativeSeconds > totalSeconds + 0.1) // 允许0.1秒误差
                {//Console.WriteLine($"错误：目标时间超出视频时长（视频仅 {totalSeconds:F2} 秒）");return false;}// 计算目标帧序号（四舍五入取最近帧）int targetFrameIndex = (int)Math.Round(relativeSeconds * fps);targetFrameIndex = Math.Clamp(targetFrameIndex, 0, totalFrames - 1); // 确保不越界//Console.WriteLine($"定位到帧序号：{targetFrameIndex}");// 直接跳转到目标帧（高效，无需遍历所有帧）capture.PosFrames = targetFrameIndex;// 读取目标帧using (Mat frame = new Mat()){bool readSuccess = capture.Read(frame);if (!readSuccess){//Console.WriteLine("错误：读取目标帧失败");return false;}// 保存图片（支持JPG/PNG等格式，根据输出后缀自动识别）bool saveSuccess = Cv2.ImWrite(outputImagePath, frame);if (saveSuccess){//Console.WriteLine($"成功保存帧到：{outputImagePath}");return true;}else{//Console.WriteLine($"错误：保存图片失败 - {outputImagePath}");return false;}}}}/// <summary>/// 将视频前部截取成帧/// </summary>/// <param name="videoPath"></param>/// <param name="outputDir"></param>/// <param name="interval"></param>/// <param name="startDateTime"></param>public static void ExtractFramesWithTimestamp(string videoPath,string outputDir,int interval = 1,string startDateTime = null){// 创建输出目录if (!Directory.Exists(outputDir)){Directory.CreateDirectory(outputDir);}// 打开视频文件 using (var capture = new VideoCapture(videoPath)){if (!capture.IsOpened()){throw new Exception($"无法打开视频文件: {videoPath}");}// 获取视频属性double fps = capture.Fps;int totalFrames = (int)capture.FrameCount;//Console.WriteLine($"视频帧率: {fps:F2} FPS，总帧数: {totalFrames}");// 解析视频开始时间DateTime? startDt = null;if (!string.IsNullOrEmpty(startDateTime)){try{startDt = DateTime.ParseExact(startDateTime,"yyyy-MM-dd HH:mm:ss",System.Globalization.CultureInfo.InvariantCulture);//Console.WriteLine($"视频开始时间: {startDt}");
                    }catch (FormatException){throw new Exception("startDateTime格式错误（应为yyyy-MM-dd HH:mm:ss），将仅使用相对时间");}}int frameCount = 0;int savedCount = 0;Mat frame = new Mat();// 循环读取帧while (true){bool readSuccess = capture.Read(frame);if (!readSuccess) break; // 视频结束// 按间隔截取帧if (frameCount % interval == 0){// 计算相对时间（秒）double relativeTime = frameCount / fps;// 计算绝对时间string absoluteTimeStr = "";if (startDt.HasValue){DateTime absoluteTime = startDt.Value.AddSeconds(relativeTime);absoluteTimeStr = absoluteTime.ToString("yyyyMMdd_HHmmss_fff");}// 生成文件名string fileName;if (!string.IsNullOrEmpty(absoluteTimeStr)){fileName = $"{absoluteTimeStr}_frame_{frameCount:D6}.jpg";}else{fileName = $"t_{relativeTime:F3}_frame_{frameCount:D6}.jpg";}// 保存图片string savePath = Path.Combine(outputDir, fileName);Cv2.ImWrite(savePath, frame);savedCount++;//Console.WriteLine($"保存: {fileName} | 相对时间: {relativeTime:F3}秒");
                    }frameCount++;}frame.Release();}}}internal class Program{static void Main(string[] args){/*// 配置参数----从视频中每隔n帧截取帧string videoPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "test.mp4");// 视频文件路径string outputDir = "frames_with_timestamp"; // 输出目录int interval = 30;                          // 截取间隔（每30帧取一次）string videoStartTime = "2025-11-05 13:35:00"; // 视频开始时间（可选）// 调用截取函数VideoFrameCaptureTool.ExtractFramesWithTimestamp(videoPath,outputDir,interval,videoStartTime);*/// 配置参数string videoPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "test.mp4");  // FFmpeg录制的视频路径string outputImagePath = "captured_frame.jpg";  // 输出图片路径string videoStartTime = "2025-05-20 14:30:00";  // 视频开始的绝对时间string targetCaptureTime = "2025-05-20 14:30:15";// 要截取的绝对时间（视频开始后15秒）// 方式1：按绝对时间截取（推荐，与外部时间戳对应）bool result1 = VideoFrameCaptureTool.CaptureFrameByAbsoluteTime(videoPath, outputImagePath, videoStartTime, targetCaptureTime);}}}

依赖类库

OpenCvSharp4

OpenCvSharp4.Extensions

OpenCvSharp4.Windows