# Playing Video Files with Multiple Video Streams

Multiple video streams refer to different video tracks contained within a single media file. These streams can vary in several ways:

• Different camera angles of the same scene
• Alternate versions with varying resolutions or bitrates
• Primary and secondary content (such as picture-in-picture)
• Different aspect ratios or formats of the same content
• Versions with or without special effects or graphics

Many popular container formats support multiple video streams, including:

• Matroska (MKV): Widely recognized for its flexibility and robust support for multiple streams
• MP4/MPEG-4: Common in both professional and consumer applications
• AVI: Although older, still widely used in some contexts
• WebM: Popular for web-based applications
• TS/MTS: Used in broadcast applications and consumer video cameras

Each format has its own characteristics and limitations regarding how it handles multiple video streams, but the TVFMediaPlayer component provides a unified approach to working with them.

The first step is to properly initialize the TVFMediaPlayer object. This involves creating the instance, configuring basic properties, and preparing it for playback:

// Define and create the MediaPlayer object
var 
  MediaPlayer1: TVFMediaPlayer;
begin
  MediaPlayer1 := TVFMediaPlayer.Create(Self);
  
  // Set container size and position if needed
  MediaPlayer1.Parent := Panel1; // Assuming Panel1 is your container
  MediaPlayer1.Align := alClient;
  
  // Configure initial state
  MediaPlayer1.DoubleBuffered := True;
  MediaPlayer1.AutoPlay := False; // We'll control playback explicitly

Next, we need to specify the media file and configure how it should be loaded:

  // Set the file name - use full path for reliability
  MediaPlayer1.FilenameOrURL := 'C:\Videos\multistream-video.mkv';
  
  // Enable audio playback (default DirectSound audio renderer will be used)
  MediaPlayer1.Audio_Play := True;
  
  // Configure audio settings if needed
  MediaPlayer1.Audio_Volume := 85; // Set volume to 85%
  
  // Set the source mode to DirectShow
  // Other options include SM_File_FFMPEG or SM_File_VLC
  MediaPlayer1.Source_Mode := SM_File_DS;

The key to working with multiple video streams is the Source_VideoStreamIndex property. This zero-based index allows you to select which video stream should be rendered:

  // Set video stream index to 1 (second stream, as index is zero-based)
  MediaPlayer1.Source_VideoStreamIndex := 1;
  
  // Start playback
  MediaPlayer1.Play();

The ability to play video files with multiple streams opens up numerous possibilities for creating rich, interactive multimedia experiences. The TVFMediaPlayer component provides a straightforward approach to implementing this functionality, with flexible options to suit different application requirements.

By following the techniques outlined in this guide, you can effectively incorporate multiple video stream support into your applications, enhancing user experience and expanding the capabilities of your multimedia projects.

Please get in touch with support if you need assistance with this functionality. Visit our GitHub page for additional code samples and implementation examples.