ASP.NET Core mvc 应用程序中的 FFMPEG 记录

Question

我正在使用 ASP.NET Core 和 ffmpeg 来录制实时视频流。当页面收到 get 请求时，流应该开始记录并使用 ffmpeg 保存到文件夹中。我想让它在访问 stop 端点时干净地关闭 ffmpeg 进程。

不幸的是，我无法在离开 Get 方法后将 'q' 发送到标准输入。使用 taskkill 需要使用 /F 使 ffmpeg 进程（不是 window）强制退出并且无法正确保存视频，从而导致文件损坏。

我尝试使用 Process.Kill()，但这也会导致文件损坏。另外，我尝试了 Process.CloseMainWindow() 的方法，但是只有当进程作为 window 启动时，我无法在我正在使用的服务器中作为 window 启动进程.

我已经将到目前为止的代码包含在下面，希望有人能引导我走上正确的道路。

using System;
...
using Microsoft.Extensions.Logging;

namespace MyApp.Controllers
{
    [Route("api/[controller]")]
    [Authorize]
    public class RecordingController : Controller
    {
        private readonly ApplicationDbContext _context;
        private readonly ILogger<HomeController> _logger;

        public RecordingController(ApplicationDbContext context, ILogger<HomeController> logger)
        {
            _context = context;
            _logger = logger;
        }

        [HttpGet]
        public async Task<ActionResult> Get()
        {

            // Define the os process
            var processStartInfo = new ProcessStartInfo()
            {
                // ffmpeg arguments
                Arguments = "-f mjpeg -i \"https://urlofstream.com/video.gci\" -r 5 \"wwwroot/video.mp4\"",
                FileName = "ffmpeg.exe",
                UseShellExecute = true
            };

            var p1 = Process.Start(processStartInfo);

            // p1.StandardInput.WriteLineAsync("q"); <-- This works here but not in the Stop method

            return Ok(p1.Id);
        }


        // GET: api/Recording/stop
        [HttpGet("stop/{pid}")]
        public ActionResult Stop(int pid)
        {
            Process processes = Process.GetProcessById(pid);
            processes.StandardInput.WriteLineAsync("q");     // Does not work, is not able to redirect input
            return Ok();
        }
    }
}

Answer 1

我已经找到了解决此问题的方法，希望对其他人有所帮助。解决方案是结合使用 Singleton 和 ConcurrentDictionary 并写入 StandardInput。您可以写入运行进程的标准输入的唯一方法是如果您仍然可以访问已启动的进程句柄，并且您无法从控制器内部访问它，因此您需要创建一个单例并将进程存储在 ConcurrentDictionary 中（这非常适合从多个线程更新）。

首先我创建了一个录音管理器class。 RecordingManager.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

namespace MyApp.Services
{
    public class RecordingManager
    {
        // Key int is the ProcessId. Value process is the running Process
        private static ConcurrentDictionary<int, Process> _processes = new ConcurrentDictionary<int, Process>();

        public Process Start()
        {
            // Define the os process
            var processStartInfo = new ProcessStartInfo()
            {
                // ffmpeg arguments
                Arguments = "-f mjpeg -i https://urlofstream.com/video.gci -r 5 wwwroot/video.mp4",
                FileName = "ffmpeg.exe",
                RedirectStandardInput = true, // Must be set to true
                UseShellExecute = false       // Must be set to false
            };

            Process p = Process.Start(processStartInfo);

            // Add the Process to the Dictionary with Key: Process ID and value as the running process
            _processes.TryAdd(p1.Id, p);

            return p;
        }

        private Process GetProcessByPid(int pid)
        {
            return _processes.FirstOrDefault(p => p.Key == pid).Value;
        }

        public void Stop(int pid)
        {
            Process p = GetProcessByPid(pid);

            // FFMPEG Expects a q written to the STDIN to stop the process
            p.StandardInput.WriteLine("q\n");
            _processes.TryRemove(pid, out p);

            // Free up resources
            p.Close()
        }
    }
}

接下来，我在 ConfigureServices 方法

中将单例添加到我的 startup.cs class

services.AddSingleton<RecordingManager>();

最后，我将单例添加到我的控制器构造函数并调用那里的方法。 RecordingController.cs

namespace MyApp.Controllers
{
    [Route("api/[controller]")]
    [Authorize]
    public class RecordingController : Controller
    {
        private readonly ApplicationDbContext _context;
        private readonly ILogger<HomeController> _logger;
        private readonly RecordingManager _recordingManager;

        public RecordingController(ApplicationDbContext context, ILogger<HomeController> logger, RecordingManager recordingManager)
        {
            _context = context;
            _logger = logger;
            _recordingManager = recordingManager;
        }

        [HttpGet]
        public async Task<ActionResult> Get()
        {
            Process p = _recordingManager.Start();
            return Ok(p.Id); // Wouldn't recommend simply returning an Ok Result here. Check for issues
        }


        // GET: api/Recording/stop
        [HttpGet("stop/{pid}")]
        public ActionResult Stop(int pid)
        {
            _recordingManager.Stop(pid);
            return Ok(); // Wouldn't recommend simply returning an Ok Result here. Check for issues
        }
    }
}

ASP.NET Core mvc 应用程序中的 FFMPEG 记录

FFMPEG recording in ASP.NET Core mvc application

asp.net

ffmpeg

recording

video-streaming

asp.net-core