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• I have a log file with RTP packets : now what ?

  9 mai 2012, par Brannon

  I have a log file with RTP packets coming off of a black box device. I also have a corresponding SDP file (RTSP DESCRIBE) for that. I need to convert this file into some kind of playable video file. Can I pass these two files to FFMpeg or VLC or something else and have it mux that data into something playable ?

  As an alternate plan, I can loop through the individual packets in code and do something with each packet. However, it seems that there are existing libraries for parsing this data. And it seems to do it by hand would be asking for a large project. Is there some kind of video file format that is a pretty raw mix of SDP and RTP ? Thanks for your time.

  Is there a way for FFmpeg or VLC to open an SDP file and then get their input packets through STDIN ?

  I generally use C#, but I could use C if necessary.

  Update 1 : Here is my unworking code. I'm trying to get some kind of output to play with ffplay, but I haven't had any luck yet. It gives me invalid data errors. It does go over all the data correctly as far as I can tell. My output is nearly as big as my input (at about 4MB).

      public class RtpPacket2
  
      {
  
          public byte VersionPXCC;
  
          public byte MPT;
  
          public ushort Sequence; // length?
  
          public uint Timestamp;
  
          public uint Ssrc;
  
          public int Version { get { return VersionPXCC >> 6; } }
  
          public bool Padding { get { return (VersionPXCC & 32) > 0; } }
  
          public bool Extension { get { return (VersionPXCC & 16) > 0; } }
  
          public int CsrcCount { get { return VersionPXCC & 0xf; } } // ItemCount
  
          public bool Marker { get { return (MPT & 0x80) > 0; } }
  
          public int PayloadType { get { return MPT & 0x7f; } } // PacketType
  
      }
  
  
  
  
  
      static void Main(string[] args)
  
      {
  
          if (args.Length != 2)
  
          {
  
              Console.WriteLine("Usage: <input rtp="rtp" file="file" /> <output 3gp="3gp" file="file">");
  
              return;
  
          }
  
          var inputFile = args[0];
  
          var outputFile = args[1];
  
          if(File.Exists(outputFile)) File.Delete(outputFile);
  
  
  
          // FROM the SDP : fmtp 96 profile-level-id=4D0014;packetization-mode=0
  
          var sps = Convert.FromBase64String("Z0LAHoiLUFge0IAAA4QAAK/IAQ=="); //      BitConverter.ToString(sps)  "67-42-C0-1E-88-8B-50-58-1E-D0-80-00-03-84-00-00-AF-C8-01"  string
  
          var pps = Convert.FromBase64String("aM44gA=="); //      BitConverter.ToString(pps)  "68-CE-38-80"   string
  
          var sep = new byte[] { 00, 00, 01 };
  
  
  
          var packet = new RtpPacket2();
  
          bool firstFrame = true;
  
          using (var input = File.OpenRead(inputFile))
  
          using (var reader = new BinaryReader(input))
  
          using (var output = File.OpenWrite(outputFile))
  
          {
  
              //output.Write(header, 0, header.Length);
  
              output.Write(sep, 0, sep.Length);
  
              output.Write(sps, 0, sps.Length);
  
              output.Write(sep, 0, sep.Length);
  
              output.Write(pps, 0, pps.Length);
  
              output.Write(sep, 0, sep.Length);
  
              while (input.Position &lt; input.Length)
  
              {
  
                  var size = reader.ReadInt16();
  
                  packet.VersionPXCC = reader.ReadByte();
  
                  packet.MPT = reader.ReadByte();
  
                  packet.Sequence = reader.ReadUInt16();
  
                  packet.Timestamp = reader.ReadUInt32();
  
                  packet.Ssrc = reader.ReadUInt32();
  
                  if (packet.PayloadType == 96)
  
                  {
  
                      if (packet.CsrcCount > 0 || packet.Extension) throw new NotImplementedException();
  
  
  
                      var header0 = reader.ReadByte();
  
                      var header1 = reader.ReadByte();
  
  
  
                      var fragmentType = header0 &amp; 0x1F; // should be 28 for video
  
                      if(fragmentType != 28) // 28 for video?
  
                      {
  
                          input.Position += size - 14;
  
                          continue;
  
                      }
  
                      var nalUnit = header0 &amp; ~0x1F;
  
                      var nalType = header1 &amp; 0x1F;
  
                      var start = (header1 &amp; 0x80) > 0;
  
                      var end = (header1 &amp; 0x40) > 0;
  
  
  
                      if(firstFrame)
  
                      {
  
                          output.Write(sep, 0, sep.Length);
  
                          output.WriteByte((byte)(nalUnit | fragmentType));
  
                          firstFrame = false;
  
                      }
  
  
  
                      for (int i = 0; i &lt; size - 14; i++)
  
                          output.WriteByte(reader.ReadByte());
  
                      if (packet.Marker)
  
                          firstFrame = true;
  
                  }
  
                  else input.Position += size - 12;
  
              }
  
          }
  
      }
  
  </output>

• Wrapping a H264 stream into a mkv container manually

  12 juin 2012, par stackVidec

  I have a stream set up that I can play in applications like VLC using the sdp handler created.

  The stream is already encoded into h264 and I now basically have a raw h264 video being streamed in.

  I've been using live 555 + openRSTP to play the stream and it writes it to a file without a container. They have outputs for file types like mov and mp4 where (looking through the code) they seem to manually write the header information of the container and then throw the video blocks into it using an abstraction of the frames being sent in and iterating through them.

  I would like to do this but write it to an mkv. Since I already have the blocks of video encoded, I would assume that I would just have to write the rest of the mkv information (header and other meta data in line with the mkv specification), but I can't find anything anywhere pertaining to that.

  I realize I can use ffmpeg for this but it would really suite the needs of my application to avoid using ffmpeg.

  Any relevant help would be greatly appreciated.

• How to make your plugin configurable – Introducing the Piwik Platform

  18 septembre 2014, par Thomas Steur — Development

  This is the next post of our blog series where we introduce the capabilities of the Piwik platform (our previous post was How to add new pages and menu items to Piwik). This time you will learn how to define settings for your plugin. For this tutorial you will need to have basic knowledge of PHP.

  What can I do with settings ?

  The Settings API offers you a simple way to make your plugin configurable within the Admin interface of Piwik without having to deal with HTML, JavaScript, CSS or CSRF tokens. There are many things you can do with settings, for instance let users configure :

  • connection infos to a third party system such as a WordPress installation.
  • select a metric to be displayed in your widget
  • select a refresh interval for your widget
  • which menu items, reports or widgets should be displayed
  • and much more

  Getting started

  In this series of posts, we assume that you have already set up your development environment. If not, visit the Piwik Developer Zone where you’ll find the tutorial Setting up Piwik.

  To summarize the things you have to do to get setup :

  • Install Piwik (for instance via git).
  • Activate the developer mode : ./console development:enable --full.
  • Generate a plugin : ./console generate:plugin --name="MySettingsPlugin". There should now be a folder plugins/MySettingsPlugin.
  • And activate the created plugin under Settings => Plugins.

  Let’s start creating settings

  We start by using the Piwik Console to create a settings template :

  ./console generate:settings

  The command will ask you to enter the name of the plugin the settings should belong to. I will simply use the above chosen plugin name “MySettingsPlugin”. There should now be a file plugins/MySettingsPlugin/Settings.php which contains already some examples to get you started easily. To see the settings in action go to Settings => Plugin settings in your Piwik installation.

  

  Adding one or more settings

  Settings are added in the init() method of the settings class by calling the method addSetting() and passing an instance of a UserSetting or SystemSetting object. How to create a setting is explained in the next chapter.

  Customising a setting

  To create a setting you have to define a name along some options. For instance which input field should be displayed, what type of value you expect, a validator and more. Depending on the input field we might automatically validate the values for you. For example if you define available values for a select field then we make sure to validate and store only a valid value which provides good security out of the box.

  For a list of possible properties have a look at the SystemSetting and UserSetting API reference.

  class Settings extends \Piwik\Plugin\Settings
  
  {
  
      public $refreshInterval;
  
  
  
      protected function init()
  
      {
  
          $this->setIntroduction('Here you can specify the settings for this plugin.');
  
  
  
          $this->createRefreshIntervalSetting();
  
      }
  
  
  
      private function createRefreshIntervalSetting()
  
      {
  
          $this->refreshInterval = new UserSetting('refreshInterval', 'Refresh Interval');
  
          $this->refreshInterval->type = static::TYPE_INT;
  
          $this->refreshInterval->uiControlType = static::CONTROL_TEXT;
  
          $this->refreshInterval->uiControlAttributes = array('size' => 3);
  
          $this->refreshInterval->description = 'How often the value should be updated';
  
          $this->refreshInterval->inlineHelp = 'Enter a number which is >= 15';
  
          $this->refreshInterval->defaultValue = '30';
  
          $this->refreshInterval->validate = function ($value, $setting) {
  
              if ($value < 15) {
  
                  throw new \Exception('Value is invalid');
  
              }
  
          };
  
  
  
          $this->addSetting($this->refreshInterval);
  
      }
  
  }

  In this example you can see some of those properties. Here we create a setting named “refreshInterval” with the display name “Refresh Interval”. We want the setting value to be an integer and the user should enter this value in a text input field having the size 3. There is a description, an inline help and a default value of 30. The validate function makes sure to accept only integers that are at least 15, otherwise an error in the UI will be shown.

  

  You do not always have to specify a PHP type and a uiControlType. For instance if you specify a PHP type boolean we automatically display a checkbox by default. Similarly if you specify to display a checkbox we assume that you want a boolean value.

  Accessing settings values

  You can access the value of a setting in a widget, in a controller, in a report or anywhere you want. To access the value create an instance of your settings class and get the value like this :

  $settings = new Settings();
  
  $interval = $settings->refreshInterval->getValue()

  Type of settings

  The Piwik platform differentiates between UserSetting and SystemSetting. User settings can be configured by any logged in user and each user can configure the setting independently. The Piwik platform makes sure that settings are stored per user and that a user cannot see another users configuration.

  A system setting applies to all of your users. It can be configured only by a user who has super user access. By default, the value can be read only by a super user as well but often you want to have it readable by anyone or at least by logged in users. If you set a setting readable the value will still be only displayed to super users but you will always be able to access the value in the background.

  Imagine you are building a widget that fetches data from a third party system where you need to configure an API URL and token. While no regular user should see the value of both settings, the value should still be readable by any logged in user. Otherwise when logged in users cannot read the setting value then the data cannot be fetched in the background when this user wants to see the content of the widget. Solve this by making the setting readable by the current user :

  $setting->readableByCurrentUser = !Piwik::isUserIsAnonymous();

  Publishing your Plugin on the Marketplace

  In case you want to share your settings or your plugin with other Piwik users you can do this by pushing your plugin to a public GitHub repository and creating a tag. Easy as that. Read more about how to distribute a plugin.

  Advanced features

  Isn’t it easy to create settings for plugins ? We never even created a file ! The Settings API already offers many possibilities but it might not yet be as flexible as your use case requires. So let us know in case you are missing something and we hope to add this feature at some point in the future.
  
  If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to send it to us.