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VLC_SDK编程指南
VLC 是一款自由、开源的跨平台多媒体播放器及框架，可播放大多数多媒体文件，以及 DVD、音频 CD、VCD 及各类流媒体协议。它可以支持目前市面上大多数的视频解码，除了Real。
VLC的SDK使用C语言写成，它的解码库部分的基础是FFMpeg，FFMpeg也是一套可以用来记录、转换数字音频、视频，并能将其转化为流的开源计算机程序。
VLC的SDK是在其客户端的安装文件根目录下，下载完VLC的客户端，并安装后，在其根目录下可以找到，例如
客户端安装在C:\Program Files\VideoLAN\VLC。因为我们是使用C#语言来调用其SDK，所以只需使用到其plugins文件夹和libvlc.dll、libvlccore.dll两个文件。
libvlc.dll和libvlccore.dll是其两个核心的动态链接库。libvlc对外提供了c语言的接口；libvlccore是VLC 媒体播放器管理线程，VLC 媒体播放器的运行核称之为libvlccore；vlc把编解码和格式解析的支持设计成了插件的形式，所以还必须要带上vlc的plugins目录里的插件。
把libvlc.dll和libvlccore.dll和plugins文件夹放在” bin/Debug”下。
由于两个动态链接库是用C语言写的。所以还要用C#封装一下非托管方法。例如：
// 创建一个libvlc实例，它是引用计数的
[DllImport("libvlc", CallingConvention = CallingConvention.StdCall, ExactSpelling = true)]
[SuppressUnmanagedCodeSecurity]
private static extern IntPtr libvlc_new(int argc, IntPtr argv);
需要引用下面两个命名空间：
using System.Runtime.InteropServices;
using System.Security;
还有一种是声明式封装引用，值得借鉴。
[AttributeUsage(AttributeTargets.Delegate, AllowMultiple = false)]
internal sealed class LibVlcFunctionAttribute : Attribute
{
public string FunctionName { get; private set; }
public LibVlcFunctionAttribute(string functionName)
{
FunctionName = functionName;
}
}
[DllImport("kernel32", SetLastError = true)]
public static extern IntPtr LoadLibrary(string lpFileName);
例如：
var libVlcDllPath = Path.Combine(dynamicLinkLibrariesPath.FullName, "libvlc.dll");//获取libvlc的路径
if (!File.Exists(libVlcDllPath))
throw new FileNotFoundException();
myLibVlcDllHandle = Win32Interops.LoadLibrary(libVlcDllPath);//获取libvlc的指针
if (myLibVlcDllHandle == IntPtr.Zero)
throw new Win32Exception(Marshal.GetLastWin32Error());
根据自定义特性名称（实际为libvlc方法名称）获取libvlc非托管方法
[DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);// hModule为LoadLibrary 方法获取的libvlc的指针，lpProcName为方法名称
例如：
internal T GetInteropDelegate<T>()
{
string vlcFunctionName = null;
try
{
var attrs = typeof(T).GetCustomAttributes(typeof(LibVlcFunctionAttribute), false);
if (attrs.Length == 0)
throw new Exception("Could not find the LibVlcFunctionAttribute.");
var attr = (LibVlcFunctionAttribute)attrs[0];
vlcFunctionName = attr.FunctionName;
procAddress = Win32Interops.GetProcAddress(myLibVlcCoreDllHandle, attr.FunctionName);//获取非托管函数的指针
if (procAddress == IntPtr.Zero)
throw new Win32Exception();
}
var delegateForFunctionPointer = Marshal.GetDelegateForFunctionPointer(procAddress, typeof(T));// 因为定义了自定义特性的属性为委托，所以需将非托管函数指针转换为委托
return (T)Convert.ChangeType(delegateForFunctionPointer, typeof(T), null);
}
catch (Win32Exception e)
{
throw new MissingMethodException(String.Format("The address of the function ‘{0}‘ does not exist in libvlc library.", vlcFunctionName), e);
}
}
释放指针
[DllImport("kernel32", SetLastError = true)]
public static extern bool FreeLibrary(IntPtr hModule);
例如：
if (myLibVlcDllHandle != IntPtr.Zero)
{
Win32Interops.FreeLibrary(myLibVlcDllHandle);
myLibVlcDllHandle = IntPtr.Zero;
}// myLibVlcDllHandle为LoadLibrary获取的指针
例如：定义libvlc中获取版本信息方法” libvlc_get_version”。
[LibVlcFunction("libvlc_get_version")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate IntPtr GetVersion();
public void GetVersion ()
{
return GetInteropDelegate<GetVersion>().Invoke().ToStringAnsi();
}
// 创建一个libvlc实例，它是引用计数的
private static extern IntPtr libvlc_new(int argc, IntPtr argv);
// 释放libvlc实例
public static extern void libvlc_release(IntPtr libvlc_instance);
//获取版本号
public static extern String libvlc_get_version();
// 从视频来源(例如Url)构建一个libvlc_meida
private static extern IntPtr libvlc_media_new_location(IntPtr libvlc_instance, IntPtr path);
// 从本地文件路径构建一个libvlc_media
private static extern IntPtr libvlc_media_new_path(IntPtr libvlc_instance, IntPtr path);
//释放media
public static extern void libvlc_media_release(IntPtr libvlc_media_inst);
// 创建libvlc_media_player(播放核心)
public static extern IntPtr libvlc_media_player_new(IntPtr libvlc_instance);
// 将视频(libvlc_media)绑定到播放器上
public static extern void libvlc_media_player_set_media(IntPtr libvlc_media_player, IntPtr libvlc_media);
// 设置图像输出的窗口
public static extern void libvlc_media_player_set_hwnd(IntPtr libvlc_mediaplayer, Int32 drawable);
//播放
public static extern void libvlc_media_player_play(IntPtr libvlc_mediaplayer);
//暂停
public static extern void libvlc_media_player_pause(IntPtr libvlc_mediaplayer);
//停止
public static extern void libvlc_media_player_stop(IntPtr libvlc_mediaplayer);
// 解析视频资源的媒体信息(如时长等)
public static extern void libvlc_media_parse(IntPtr libvlc_media);
// 返回视频的时长(必须先调用libvlc_media_parse之后，该函数才会生效)
public static extern Int64 libvlc_media_get_duration(IntPtr libvlc_media);
// 当前播放的时间
public static extern Int64 libvlc_media_player_get_time(IntPtr libvlc_mediaplayer);
// 设置播放位置(拖动)
public static extern void libvlc_media_player_set_time(IntPtr libvlc_mediaplayer, Int64 time);
//释放meidiaPlayer
public static extern void libvlc_media_player_release(IntPtr libvlc_mediaplayer);
方法具体含义请参看其c语言的封装库具体内容。
播放本地文件
libvlc_new=>libvlc_media_player_new=>libvlc_media_player_set_hwnd=>libvlc_media_new_path=>libvlc_media_parse=>libvlc_media_player_set_media=>libvlc_media_release=>libvlc_media_player_play=>libvlc_media_player_stop=>libvlc_media_player_release=>libvlc_media_release=>libvlc_release
播放URL
libvlc_new=>libvlc_media_player_new=>libvlc_media_player_set_hwnd=>libvlc_media_new_location=>libvlc_media_parse=>libvlc_media_player_set_media=>libvlc_media_release=>libvlc_media_player_play=>libvlc_media_player_stop=>libvlc_media_player_release=>libvlc_media_release=>libvlc_release
开启硬件加速命令为：avcodec-hw=any
方法为：libvlc_media_add_option (IntPtr mediaInstance, IntPtr mrl)；
var handle = GCHandle.Alloc(Encoding.UTF8.GetBytes(option), GCHandleType.Pinned);//option为命令
//两个参数的获取
mrl= handle.AddrOfPinnedObject();
mediaInstance= libvlc_new(null);
Vlc.DotNet是一个对VLC封装的C#开源架构。使用Vlc.DotNet框架可以播放本地文件和URL网络视频。在研究过程中，目前还为发现关于解码方面的封装应用。
Vlc.DotNet框架包含5个DLL，如下
|
名称 |
版本号 |
|
Vlc.DotNet.Core.dll |
2014.10.15.0 |
|
Vlc.DotNet.Core.Interops.dll |
2014.10.15.0 |
|
Vlc.DotNet.Forms.dll |
2014.10.15.0 |
|
Vlc.DotNet.Silverlight.dll |
2014.10.15.0 |
|
Vlc.DotNet.Wpf.dll |
2014.10.15.0 |
根据你做的程序是用什么写的来添加不同的引用，例如：你使用WPF来做的程序就选择Vlc.DotNet.Wpf.dll、Vlc.DotNet.Forms.dll、Vlc.DotNet.Core.dll、Vlc.DotNet.Core.Interops.dll添加到项目中并引用。
把libvlc.dll和libvlccore.dll和plugins文件夹放在” bin/Debug”下。
具体示例可以参见Vlc.DotNet自带的demo，简要说明如下：
xmlns:wpf="clr-namespace:Vlc.DotNet.Wpf;assembly=Vlc.DotNet.Wpf"
<wpf:VlcControl Grid.Row="0" Grid.Column="0" x:Name="myControl1"/>
myControl1.VlcLibDirectoryNeeded += OnVlcControlNeedsLibDirectory;
private void OnVlcControlNeedsLibDirectory(object sender, Forms.VlcLibDirectoryNeededEventArgs e)
{
var currentAssembly = Assembly.GetEntryAssembly();
var currentDirectory = new FileInfo(currentAssembly.Location).DirectoryName;
if (currentDirectory == null)
return;
e.VlcLibDirectory = new DirectoryInfo(Path.Combine(currentDirectory, @"VLC\"));
}
播放本地文件
myControl1.MediaPlayer.Play(new FileInfo(Environment.CurrentDirectory + @"\video\wow" + i + @".mp4"), null);
播放URI文件
myControl1..MediaPlayer.Play
(new Uri("rtsp://192.168.1.181"),new string[] { "avcodec-hw=any" });//开启硬件加速
myControl1.MediaPlayer.Stop();
其他功能可参见开源框架源码。
VLC客户端可以作为流媒体转发服务端。如下图所以操作：
显示的方式使用HTML5Video标签，Html5的Video标签只支持三种视频格式，OGG，WebM，MP4，经过测试，video标签只能播放VLC转发的OGG格式视频。
建立一个html文件：
<html>
<head>
<title>HTTP Live Streaming Player</title>
</head>
<body>
<video id="vplayer"
height="300"
width="400"
controls="controls"
src="http://192.168.1.5:8880/ttl" />
</body>
</html>
也可转发本地视频文件流。
上图用客户端实现的功能，可以用SDK实现。
其C语言库为libvlc_vlm.h。在这个文件中包含了“推流器”广播和点播的控制功能。
我把在c#中封装的实现推流器功能核心SDK方法归纳如下：
//添加广播
[LibVlcFunction("libvlc_vlm_add_broadcast")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate int VlmAddBroadcast(IntPtr libvlc_instance, IntPtr name, IntPtr input, IntPtr output, int optionNumber, string[] options, bool isEnabled, bool isLoop);
//播放广播
[LibVlcFunction("libvlc_vlm_play_media")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate int PlayVlmMedia(IntPtr libvlcInstance, IntPtr broadcastName);
//关闭广播
[LibVlcFunction("libvlc_vlm_stop_media")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate int StopVlmMedia(IntPtr libvlcInstance, IntPtr broadcastName);
//删除广播
[LibVlcFunction("libvlc_vlm_del_media")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate void VlmDelMedia(IntPtr libvlcInstance,IntPtr mediaName);
//释放广播示例
[LibVlcFunction("libvlc_vlm_release")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
internal delegate void ReleaseVlm(IntPtr libvlcInstance);
在赋值参数时需要注意自定义广播名称、视频源地址和目标地址的字符串转换为指针时需要做如下操作：
var handleName = GCHandle.Alloc(Encoding.UTF8.GetBytes(name), GCHandleType.Pinned);//广播名称
var handleInput = GCHandle.Alloc(Encoding.UTF8.GetBytes(input), GCHandleType.Pinned);//视频源
var handleOutput = GCHandle.Alloc(Encoding.UTF8.GetBytes(output), GCHandleType.Pinned);//目标
具体实现方式如下：
//播放广播
public bool PlayVlmMedia(string broadcastName, string input, string output, int optionNumber, string[] options, bool isEnabled, bool isLoop)
{
bool result = false;
if (_manager.AddVlmBroadcast(broadcastName, input, output, optionNumber, options, isEnabled, isLoop))//添加广播地址
result = _manager.PlayVlmMedia(broadcastName);//播放
return result;
}
//停止播放广播
public bool StopVlmMedia(string broadcastName)
{
return _manager.StopVlmMedia(broadcastName);
}
传入参数：
String mediaName = "IPCTest";//广播名称
String url = "rtsp://192.168.1.181";//源地址//string sout = "#transcode{vcodec=h264,vb=800,scale=1,acodec=mpga,ab=128,channels=2,samplerate=44100}:http{mux=ts,dst=:7777/}";//转码目标格式H264格式
string sout = "#transcode{vcodec=theo,vb=1600,scale=1,acodec=vorb,ab=128,channels=2,samplerate=44100}:http{mux=ogg,dst=:8880/ttl}";//转码格式为ogg，端口号为8880，标识为ttl
string[] options = {"screen-top=0",
"screen-left=0",
"screen-width=640",
"screen-height=480",
"screen-fps=10"};//码流参数
_vlcControl.PlayVlmMedia(mediaName, url, sout, 5, options, true, false);//转码后广播
实现实时流回调的流程与普通播放方式相同，唯一区别在于，普通播放方式需要指定播放窗体，实时流回调不需指定播放窗体，只需在回调方法中获取视频流数据然后用自定义方式显示出来。具体操作如下：
首先封装三个委托方法：
//锁定一个图片缓冲区
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]//声明对c语言的约束
public delegate IntPtr VideoLockCB(IntPtr opaque, IntPtr planes);
//解锁一个图片缓冲区
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void VideoUnlockCB(IntPtr opaque, IntPtr picture, IntPtr planes);
//显示图片
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void VideoDisplayCB(IntPtr opaque, IntPtr picture);
其次封装两个方法：
//设置解码后视频格式
[LibVlcFunction("libvlc_video_set_format")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void VideoSetFormat(IntPtr mediaPlayerInstance, IntPtr chroma, UInt32 width, UInt32 height, UInt32 pitch);
//设置实时流视频解析回调
[LibVlcFunction("libvlc_video_set_callbacks")]
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void VideoSetCallBacks(IntPtr mediaPlayInstance, VideoLockCB lockCB, VideoUnlockCB unlockCB, VideoDisplayCB displayCB, IntPtr opaque);
具体调用过程如下：
IntPtr vlcInstance=libvlc_new();//
IntPtr mediaPlayerInstance=libvlc_media_player_new(vlcInstance);
创建实例常用两种方式，一种是根据本地文件路径。
IntPtr mediaInstance= libvlc_media_new_path(vlcInstance,"本地文件地址");
一种是根据网络地址
IntPtr mediaInstance= libvlc_media_new_location(vlcInstance,"网络地址");
经实例运行验证，不是用此方法普通方式和回调方式的视频流也可以播放。
libvlc_media_parse(mediaInstance);
libvlc_media_player_set_media(mediaPlayerInstance, mediaInstance);
libvlc_media_release(IntPtr libvlc_media_inst);
VideoSetFormat(_mediaPlayer, "RV32", width, height, pitch);//RGBA 颜色不对，YUYV显示错误，I420程序跳出
预先设置的变量
private const int _width = 1920;
private const int _height = 1080;
private const int _pixelBytes = 4;
private const int _pitch = _width * _pixelBytes;
private IntPtr _buff = IntPtr.Zero;
初始化三个委托
private VideoLockCB _videoLockCB;
private VideoUnlockCB _videoUnlockCB;
private VideoDisplayCB _videoDisplayCB;
if (_videoLockCB == null)
_videoLockCB = new VideoLockCB(VideoLockCallBack);
if (_videoUnlockCB == null)
_videoUnlockCB = new VideoUnlockCB(VideoUnlockCallBack);
if (_videoDisplayCB == null)
_videoDisplayCB = new VideoDisplayCB(VideoDiplayCallBack);
设置回调
VideoSetCallBacks(_mediaPlayer, lockCB, unlockCB, displayCB, IntPtr.Zero);
使用回调前前先定义一个线程锁。
bool obj = false;
private void Lock()
{
obj = true;
}
private void Unlock()
{
obj = false;
}
private bool Islock()
{
return obj;
}
锁定一个图片缓冲区时先锁定，然后初始化这个缓冲区。
private IntPtr VideoLockCallBack(IntPtr opaque, IntPtr planes)
{
Lock();
_buff = Marshal.AllocHGlobal(_pitch * _height);
Marshal.WriteIntPtr(planes, _buff);//初始化
return IntPtr.Zero;
}
显示图片的委托中进行的处理，我选择了解析为Bitmap，然后显示在pictureBox上。
if (Islock())
{
if (DateTime.Now.Subtract(_start).TotalSeconds > 2)
{
using (Bitmap bmp = new Bitmap(_width, _height, PixelFormat.Format32bppPArgb))
{
Rectangle rect = new Rectangle(0, 0, _width, _height);
BitmapData bp = bmp.LockBits(rect, ImageLockMode.WriteOnly, bmp.PixelFormat);
CopyMemory(bp.Scan0, _buff, (uint)(_height * _pitch));
bmp.UnlockBits(bp);
//bmp.Save("c:\\vlc.bmp");
Bitmap bitmap = (Bitmap)bmp.Clone();
if (this.pictureBox1.Image != null)
this.pictureBox1.Image.Dispose();
this.pictureBox1.Image = bitmap;
}
}
}
此委托中用到了一个winapi函数
[DllImport("kernel32.dll", EntryPoint = "RtlMoveMemory")]
private static extern void CopyMemory(IntPtr Destination, IntPtr Source, uint Length);
解锁图片缓冲区
private void VideoUnlockCallBack(IntPtr opaque, IntPtr picture, IntPtr planes)
{
Marshal.FreeHGlobal(_buff);//释放缓冲区
Unlock();
}
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原文地址：http://www.cnblogs.com/smartsensor/p/4343769.html
