c#提取视频缩略图问题

2012-02-13 09:24:43 938 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

C# 结合 FFmpeg 实现视频转码与格式转换摘要：本文介绍了在C#中集成FFmpeg实现视频处理的两种主要方法。通过Process类可直接调用FFmpeg命令行工具，完成格式转换、视频剪辑等操作；也可使用Xabe.FFmpeg封装库简化开发。文章详细讲解了基础命令使用、常见转码任务示例，并提供了进阶优化建议和错误排查方法。这种集成方案适用于构建视频转码平台、自动化处理系统等场景，既保留了FFmpeg的强大功能，又发挥了C#的开发效率优势。（150字）阅读详情

想做个东西，主要就是想提取视频文件的缩略图，使其显示在网页上，分不多望见谅

...全文

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切换为时间正序

哈哈gogo 2014-05-03

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我来看看这是怎么回事

porschev 2012-02-13

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[Quote=引用 3 楼 nonocast 的回复:]

第一帧很可能是黑屏，然后抽样计算一下，黑屏的话跳一下再截
[/Quote]

这个那我那方法里没有，一般都偷懒，取了个八秒以后的一帧

nonocast 2012-02-13

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第一帧很可能是黑屏，然后抽样计算一下，黑屏的话跳一下再截

porschev 2012-02-13

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我把项目中用的ffmepg的类给你吧。。自己看



using System;

using System.Collections.Generic;

using System.Text;

using System.ComponentModel;

using System.Runtime.CompilerServices;

using System.IO;

using System.Web;

namespace AUV5.Common

{

    public class FormatConverter

    {

        //FFmpeg配置信息

        private string ffmpegpath = "/FFmpeg/ffmpeg.exe";//FFmpeg的服务器路径

        private string imgsize = "400*300";     //视频截图大小

        private string videosize = "480*360"; //视频大小

        #region 也可将信息添加到配置文件中

        //public static string ffmpegpath = ConfigurationManager.AppSettings["ffmpeg"];

        //public static string imgsize = ConfigurationManager.AppSettings["imgsize"];

        //public static string videosize = ConfigurationManager.AppSettings["videoize"];

        #endregion



        private string destVideo = "";



        /// <summary>

        /// 视频路径

        /// </summary>

        public string DestVideo

        {

            get { return destVideo; }

            set { destVideo = value; }

        }

        private string destImage = "";



        /// <summary>

        /// 图片路径

        /// </summary>

        public string DestImage

        {

            get { return destImage; }

            set { destImage = value; }

        }



        /// <summary>

        /// 视频长度

        /// </summary>

        public string VideoLength { get; set; }



        //文件类型

        public enum VideoType

        {

            [Description(".avi")]

            AVI,

            [Description(".mov")]

            MOV,

            [Description(".mpg")]

            MPG,

            [Description(".mp4")]

            MP4,

            [Description(".flv")]

            FLV

        }

        /// <summary>

        /// 返回枚举类型的描述信息

        /// </summary>

        /// <param name="myEnum"></param>

        /// <returns></returns>

        private string GetDiscription(System.Enum myEnum)

        {



            System.Reflection.FieldInfo fieldInfo = myEnum.GetType().GetField(myEnum.ToString());

            object[] attrs = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), true);

            if (attrs != null && attrs.Length > 0)

            {

                DescriptionAttribute desc = attrs[0] as DescriptionAttribute;

                if (desc != null)

                {

                    return desc.Description.ToLower();

                }

            }

            return myEnum.ToString();

        }

        //将GetDesCription定义为扩展方法,需.net3.5

        //public static string Description(this Enum myEnum)

        //{

        //    return GetDiscription(myEnum);

        //}



        //构造函数

        //创建目录

        public FormatConverter()

        {

        }



        #region 使用FFmpeg进行格式转换



        /// <summary>

        /// 运行格式转换

        /// </summary>

        /// <param name="sourceFile">要转换文件绝对路径</param>

        /// <param name="destPath">转换结果存储的相对路径</param>

        /// <param name="videotype">要转换成的文件类型</param>

        /// <param name="createImage">是否生成截图</param>

        /// <returns>

        /// 执行成功返回空，否则返回错误信息

        /// </returns>

        public string Convert(string sourceFile, string destPath,string uniquename, VideoType videotype, bool createImage,bool getDuration)

        {

            //取得ffmpeg.exe的物理路径

            string ffmpeg = System.Web.HttpContext.Current.Server.MapPath(ffmpegpath);

            if (!File.Exists(ffmpeg))

            {

                return "找不到格式转换程序！";

            }

            if (!File.Exists(sourceFile))

            {

                return "找不到源文件！";

            }

            //string uniquename = FileHelper.GetUniqueFileName();

            string filename = uniquename + GetDiscription(videotype);

            string destFile = HttpContext.Current.Server.MapPath(destPath + filename);

            //if (Path.GetExtension(sourceFile).ToLower() != GetDiscription(videotype).ToLower())

            //{

            System.Diagnostics.ProcessStartInfo FilestartInfo = new System.Diagnostics.ProcessStartInfo(ffmpeg);

            FilestartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;

            /*ffmpeg参数说明

             * -i 1.avi   输入文件

             * -ab/-ac <比特率> 设定声音比特率，前面-ac设为立体声时要以一半比特率来设置，比如192kbps的就设成96，转换 

                均默认比特率都较小，要听到较高品质声音的话建议设到160kbps（80）以上

             * -ar <采样率> 设定声音采样率，PSP只认24000

             * -b <比特率> 指定压缩比特率，似乎ffmpeg是自动VBR的，指定了就大概是平均比特率，比如768，1500这样的   --加了以后转换不正常

             * -r 29.97 桢速率（可以改，确认非标准桢率会导致音画不同步，所以只能设定为15或者29.97）

             * s 320x240 指定分辨率

             * 最后的路径为目标文件

             */

            FilestartInfo.Arguments = " -i " + sourceFile + " -ab 80 -ar 22050 -r 29.97 -s " + videosize + " " + destFile;

            //FilestartInfo.Arguments = "-y -i " + sourceFile + " -s 320x240 -vcodec h264 -qscale 4  -ar 24000 -f psp -muxvb 768 " + destFile;

            try

            {

                //转换

                System.Diagnostics.Process.Start(FilestartInfo);

                destVideo = destPath + filename;

            }

            catch

            {

                return "格式转换失败！";

            }

            //}

            //格式不需要转换则直接复制文件到目录

            //else

            //{

            //    File.Copy(sourceFile, destFile,true);

            //    destVideo = destPath + filename;

            //}

            //提取视频长度

            if (getDuration)

            {

                VideoLength = GetVideoDuration(ffmpeg, sourceFile);

            }

            //提取图片

            if (createImage)

            {

                //定义进程

                System.Diagnostics.ProcessStartInfo ImgstartInfo = new System.Diagnostics.ProcessStartInfo(ffmpeg);



                //截大图

                string imgpath = destPath + uniquename + ".jpg";// FileHelper.GetUniqueFileName(".jpg");

                ConvertImage(sourceFile, imgpath, imgsize, ImgstartInfo);



                //截小图

                imgpath = destPath + uniquename + "_thumb.jpg";

                DestImage = ConvertImage(sourceFile, imgpath, "80*80", ImgstartInfo);



            }

            return "";

        }



        private string ConvertImage(string sourceFile, string imgpath, string imgsize, System.Diagnostics.ProcessStartInfo ImgstartInfo)

        {

            ImgstartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;

            /*参数设置

             * -y（覆盖输出文件，即如果生成的文件（flv_img）已经存在的话，不经提示就覆盖掉了）

             * -i 1.avi 输入文件

             * -f image2 指定输出格式

             * -ss 8 后跟的单位为秒，从指定时间点开始转换任务

             * -vframes

             * -s 指定分辨率

             */

            //duration: 00:00:00.00

            string[] time = VideoLength.Split(':');

            int seconds = int.Parse(time[0]) * 60 * 60 + int.Parse(time[1]) * 60 + int.Parse(time[2]);

            int ss = seconds > 5 ? 5 : seconds - 1;

            ImgstartInfo.Arguments = " -i " + sourceFile + " -y -f image2 -ss " + ss.ToString() + " -vframes 1 -s " + imgsize + " " + HttpContext.Current.Server.MapPath(imgpath);

            try

            {

                System.Diagnostics.Process.Start(ImgstartInfo);

                return imgpath;

            }

            catch

            {

                return "";

            }

        }





        private string GetVideoDuration(string ffmpegfile, string sourceFile)

        {

            using (System.Diagnostics.Process ffmpeg = new System.Diagnostics.Process())

            {

                String duration;  // soon will hold our video's duration in the form "HH:MM:SS.UU"

                String result;  // temp variable holding a string representation of our video's duration

                StreamReader errorreader;  // StringWriter to hold output from ffmpeg



                // we want to execute the process without opening a shell

                ffmpeg.StartInfo.UseShellExecute = false;

                //ffmpeg.StartInfo.ErrorDialog = false;

                ffmpeg.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;

                // redirect StandardError so we can parse it

                // for some reason the output comes through over StandardError

                ffmpeg.StartInfo.RedirectStandardError = true;



                // set the file name of our process, including the full path

                // (as well as quotes, as if you were calling it from the command-line)

                ffmpeg.StartInfo.FileName = ffmpegfile;



                // set the command-line arguments of our process, including full paths of any files

                // (as well as quotes, as if you were passing these arguments on the command-line)

                ffmpeg.StartInfo.Arguments = "-i " + sourceFile;



                // start the process

                ffmpeg.Start();



                // now that the process is started, we can redirect output to the StreamReader we defined

                errorreader = ffmpeg.StandardError;



                // wait until ffmpeg comes back

                ffmpeg.WaitForExit();



                // read the output from ffmpeg, which for some reason is found in Process.StandardError

                result = errorreader.ReadToEnd();



                // a little convoluded, this string manipulation...

                // working from the inside out, it:

                // takes a substring of result, starting from the end of the "Duration: " label contained within,

                // (execute "ffmpeg.exe -i somevideofile" on the command-line to verify for yourself that it is there)

                // and going the full length of the timestamp



                duration = result.Substring(result.IndexOf("Duration: ") + ("Duration: ").Length, ("00:00:00").Length);

                return duration;

            }

        }



        #endregion



    }

}

nonocast 2012-02-13

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ffmepg

c#提取视频缩略图问题

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