ASP.NET Web Forms Video Player with HLS in C¶

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How it works¶

A browser cannot host a native video player, so the SDK does not run in the browser at all. It runs inside the ASP.NET process on the server: a MediaBlocksPipeline reads the source, encodes it to H.264 and AAC and writes an HLS playlist with its segments into a folder under the web site. IIS serves those files as static content. The HlsPlayer server control renders an HTML5 <video> element that plays the playlist with hls.js; Safari plays HLS natively.

graph LR
    Source["Source: file, URL, RTSP or device"] --> H264EncoderBlock
    Source --> AACEncoderBlock
    H264EncoderBlock --> HLSSinkBlock
    AACEncoderBlock --> HLSSinkBlock
    HLSSinkBlock --> IIS["IIS static files (.m3u8 + .ts)"]
    IIS --> Browser["Browser: HTML5 video + hls.js"]

The control builds and manages this pipeline for you through HlsStreamManager. You only place the control on the page and set its Source.

Requirements¶

An ASP.NET Web Forms Web Application project targeting .NET Framework 4.7.2.
A 64-bit application pool (the SDK native libraries are x64). For IIS Express, use the 64-bit C:\Program Files\IIS Express\iisexpress.exe.
The NuGet packages and the output folder settings below. The redist packages copy the native libraries to bin\x64 only when the output goes straight to bin\.

<PropertyGroup>
  <TargetFramework>net472</TargetFramework>
  <OutputPath>bin\</OutputPath>
  <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
  <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
  <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
</PropertyGroup>

<ItemGroup>
  <Reference Include="System.Web" />
  <PackageReference Include="VisioForge.DotNet.Core.UI.WebForms" Version="2026.10.2" />
  <PackageReference Include="VisioForge.DotNet.Core" Version="2026.10.2" />
  <PackageReference Include="VisioForge.CrossPlatform.Core.Windows.x64" Version="2026.9.11" />
  <PackageReference Include="VisioForge.CrossPlatform.Libav.Windows.x64.UPX" Version="2026.9.11" />
</ItemGroup>

web.config¶

Three items are mandatory:

shadowCopyBinAssemblies="false". The SDK loads its native libraries from the x64 folder next to VisioForge.Core.dll. ASP.NET normally shadow-copies the bin assemblies to Temporary ASP.NET Files, where that folder does not exist, and the natives are not found.
The .m3u8 MIME type. IIS and IIS Express do not serve .m3u8 files without it.
Binding redirects. A web application reads them from web.config only. The build generates the <dependentAssembly> entries into bin\<YourAssembly>.dll.config; after the first build, copy them from there into web.config.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.7.2" />
    <httpRuntime targetFramework="4.7.2" />
    <!-- The SDK loads its native libraries from bin\x64; shadow copying would hide that folder. -->
    <hostingEnvironment shadowCopyBinAssemblies="false" />
  </system.web>
  <system.webServer>
    <staticContent>
      <remove fileExtension=".m3u8" />
      <mimeMap fileExtension=".m3u8" mimeType="application/vnd.apple.mpegurl" />
    </staticContent>
  </system.webServer>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <!-- Paste the <dependentAssembly> entries from bin\<YourAssembly>.dll.config here. -->
    </assemblyBinding>
  </runtime>
</configuration>

Add the player to a page¶

The page must be asynchronous, because the control starts the stream in a page async task. Register the control's namespace and place it on the page:

<%@ Page Language="C#" Async="true" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="MyWebApp.Default" %>
<%@ Register TagPrefix="vf" Namespace="VisioForge.Core.UI.WebForms" Assembly="VisioForge.Core.UI.WebForms" %>

<vf:HlsPlayer ID="player" runat="server" Width="960px" Height="540px" Source="~/Media/sample.mp4" />

On the first request for a source, the control starts its pipeline, waits for the first playlist and renders the video element. Later requests for the same source reuse the running stream.

Source forms¶

`Source` value	What is played
`C:\Videos\clip.mp4` or `~/Media/clip.mp4`	A local file; a `~/` path is resolved under the web site
`https://example.com/clip.mp4`	A file or stream over HTTP or HTTPS
`rtsp://192.168.1.21:554/stream`	An IP camera; set `Login` and `Password` for its credentials
`device://<camera name>`	A capture device by name, or the first camera for `device://`; add `AudioSource="device://<microphone name>"` for sound

Other control properties:

Property	Default	Purpose
`OutputFolder`	`~/hls`	Folder under the site where the playlist and segments are written, one subfolder per source
`AutoPlay`	`false`	Start playback when the page loads
`Muted`	`false`	Start muted (browsers usually allow autoplay only when muted)
`HlsJsUrl`	`https://cdn.jsdelivr.net/npm/hls.js@1`	Where the page loads hls.js from
`PlaylistUrl`	(read-only)	The playlist URL, set once the stream has started

If the stream cannot start, the control renders the error message in a <p class="vf-hls-error"> element instead of the video.

Choose the source in code-behind¶

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using VisioForge.Core.UI.WebForms;

namespace MyWebApp
{
    public partial class Default : Page
    {
        protected TextBox edSource;
        protected TextBox edLogin;
        protected TextBox edPassword;
        protected HlsPlayer player;

        protected void btPlay_Click(object sender, EventArgs e)
        {
            // The stream starts when the page renders.
            player.Source = edSource.Text.Trim();
            player.Login = edLogin.Text;
            player.Password = edPassword.Text;
        }

        protected void btStop_Click(object sender, EventArgs e)
        {
            // Stops the stream for every viewer of this source and clears Source.
            player.Stop();
        }
    }
}

HlsStreamManager.Stop(source) and HlsStreamManager.StopAll() are the lower-level API behind Stop(): they stop a stream by its resolved source, or every stream, without a control.

Licensing and shutdown¶

Set the license certificate once in Application_Start; every pipeline started afterwards uses it. Without it the SDK runs in trial mode. Stop all streams and release the SDK in Application_End:

using System;
using System.IO;
using System.Web;
using VisioForge.Core.UI.WebForms;

namespace MyWebApp
{
    public class Global : HttpApplication
    {
        protected void Application_Start(object sender, EventArgs e)
        {
            // Your license certificate file, kept outside the public site content.
            HlsStreamManager.LicenseCertificate =
                File.ReadAllBytes(Server.MapPath("~/App_Data/license.vfcert"));
        }

        protected void Application_End(object sender, EventArgs e)
        {
            HlsStreamManager.StopAll();
        }
    }
}

Notes for production¶

Streams are shared and run until stopped. Every viewer of the same source watches the same pipeline. A live stream (a camera or RTSP source) keeps running after its viewers leave, until Stop() on the control, HlsStreamManager.Stop(source) or HlsStreamManager.StopAll() is called; a file stream also ends when the file does.
The first request sets the stream. Streams are shared per Source, so the AudioSource, Login and Password of the first request apply to every later viewer of that source.
A file plays in real time and starts over on the next request. A file or HTTP source is streamed from its beginning at real-time pace, so the live playlist keeps up with its viewers. The control requests its stream on every page request while Source is set, so after the file has ended, the next postback of that page plays it again from the beginning; call Stop() or clear Source to end it. A stream that fails with a pipeline error is dropped the same way; the next request for that Source starts it again, and the error is written to the server trace.
Write access. The application pool identity needs write access to the HLS output folder (~/hls by default).
Capture devices under IIS. Whether an IIS worker process can open a camera or microphone depends on the server's session and service configuration. On servers, prefer file and RTSP sources.
No CDN access. On an intranet server without internet access, host hls.js on the site and point HlsJsUrl at its URL, for example HlsJsUrl="/Scripts/hls.min.js".

Samples¶

HLS Media Web Forms - plays a file, an HTTP URL or an RTSP camera entered on the page.
HLS Webcam Web Forms - streams a webcam and a microphone picked from the server's device lists.