add lowLatency option

README.md

@@ -39,7 +39,10 @@ registerWith(options: {'platforms': ['windows', 'macos', 'linux']}); // only the
 
 To select [other decoders](https://github.com/wang-bin/mdk-sdk/wiki/Decoders), pass options like this
 ```dart
-registerWith(options: {'video.decoders': ['D3D11', 'NVDEC', 'FFmpeg']}); // windows
+registerWith(options: {
+    'video.decoders': ['D3D11', 'NVDEC', 'FFmpeg']
+    'lowLatency': 1, // optional for network streams
+    }); // windows
 ```
 
 ### Backend Player API

lib/fvp.dart

@@ -17,6 +17,8 @@ import 'src/video_player_mdk.dart'
 ///
 /// "maxWidth", "maxHeight": texture max size. if not set, video frame size is used. a small value can reduce memory cost, but may result in lower image quality.
 ///
+/// 'lowLatency': int. default is 0. reduce network stream latency. 1: for vod. 2: for live stream, may drop frames to ensure the latest content is displayed
+///
 /// "player": backend player properties of type Map<String, String>. See https://github.com/wang-bin/mdk-sdk/wiki/Player-APIs#void-setpropertyconst-stdstring-key-const-stdstring-value
 ///
 /// "global": backend global options of type Map<String, Object>. See https://github.com/wang-bin/mdk-sdk/wiki/Global-Options

lib/src/video_player_mdk.dart

@@ -94,6 +94,7 @@ class MdkVideoPlayerPlatform extends VideoPlayerPlatform {
   static int? _maxWidth;
   static int? _maxHeight;
   static bool? _fitMaxSize;
+  static int _lowLatency = 0;
   static int _seekFlags = mdk.SeekFlag.fromStart | mdk.SeekFlag.inCache;
   static List<String>? _decoders;
   static final _mdkLog = Logger('mdk');
@@ -118,6 +119,7 @@ class MdkVideoPlayerPlatform extends VideoPlayerPlatform {
       if ((options['fastSeek'] ?? false) as bool) {
         _seekFlags |= mdk.SeekFlag.keyFrame;
       }
+      _lowLatency = (options['lowLatency'] ?? 0) as int;
       _maxWidth = options["maxWidth"];
       _maxHeight = options["maxHeight"];
       _fitMaxSize = options["fitMaxSize"];
@@ -196,13 +198,23 @@ class MdkVideoPlayerPlatform extends VideoPlayerPlatform {
     player.setProperty("keep_open", "1");
     player.setProperty('avio.protocol_whitelist',
         'file,rtmp,http,https,tls,rtp,tcp,udp,crypto,httpproxy,data,concatf,concat,subfile');
+    player.setProperty('avformat.rtsp_transport', 'tcp');
     _playerOpts?.forEach((key, value) {
       player.setProperty(key, value);
     });
 
     if (_decoders != null) {
       player.videoDecoders = _decoders!;
     }
+    if (_lowLatency > 0) {
+      player.setProperty('avformat.fflags', '+nobuffer');
+      player.setProperty('avformat.fpsprobesize', '0');
+      if (_lowLatency > 1) {
+        player.setBufferRange(min: 0, max: 1000, drop: true);
+      } else {
+        player.setBufferRange(min: 0);
+      }
+    }
 
     if (dataSource.httpHeaders.isNotEmpty) {
       String headers = '';