如何使用vlcj从指定分钟位置开始流式传输视频？

Hey there! I see you've already got your vlcj environment set up correctly with working initialization code. To make your video start streaming from a specific minute position, here's a straightforward way to adjust your code:

First, let's recap your existing working initialization code (I'll fill in the truncated parts for context):

import uk.co.caprica.vlcj.binding.LibVlc;
import uk.co.caprica.vlcj.binding.RuntimeUtil;
import uk.co.caprica.vlcj.player.MediaPlayer;
import uk.co.caprica.vlcj.player.MediaPlayerFactory;
import uk.co.caprica.vlcj.player.embedded.EmbeddedMediaPlayer;
import uk.co.caprica.vlcj.runtime.LibXUtil;
import java.io.File;
import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;

public class VlcStreamer {
    public static void main(String[] args) throws Exception {
        // Set VLC plugin path and load native libraries
        System.setProperty("VLC_PLUGIN_PATH", "C:\\Program Files\\VideoLAN\\VLC\\plugins");
        File vlcInstallPath = new File("C:\\Program Files\\VideoLAN\\VLC");
        NativeLibrary.addSearchPath(RuntimeUtil.getLibVlcLibraryName(), vlcInstallPath.getAbsolutePath());
        Native.loadLibrary(RuntimeUtil.getLibVlcLibraryName(), LibVlc.class);
        LibXUtil.initialise();

        // Create media player factory and player
        MediaPlayerFactory mediaPlayerFactory = new MediaPlayerFactory();
        EmbeddedMediaPlayer mediaPlayer = mediaPlayerFactory.newEmbeddedMediaPlayer();

        // Your existing code to set up streaming (e.g., render surface, stream options)
        // ...
    }
}

Now, to add the functionality to start from a specific minute, follow these steps:

• Calculate target time in milliseconds: vlcj uses milliseconds for time positioning, so convert your desired minute mark to ms. For example, starting at 5 minutes would be 5 * 60 * 1000 = 300000 ms.
• Wait for media to be ready before seeking: Seeking immediately after loading media might fail because the media hasn't finished parsing. Use a media event listener to trigger the seek once the media is prepared.

Here's the modified code with this functionality included:

import uk.co.caprica.vlcj.binding.LibVlc;
import uk.co.caprica.vlcj.binding.RuntimeUtil;
import uk.co.caprica.vlcj.player.MediaPlayer;
import uk.co.caprica.vlcj.player.MediaPlayerFactory;
import uk.co.caprica.vlcj.player.embedded.EmbeddedMediaPlayer;
import uk.co.caprica.vlcj.runtime.LibXUtil;
import uk.co.caprica.vlcj.player.MediaEventListener;
import uk.co.caprica.vlcj.player.MediaEventAdapter;
import java.io.File;
import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;

public class VlcStreamer {
    // Define your target start minute here
    private static final int START_MINUTE = 5;

    public static void main(String[] args) throws Exception {
        // VLC initialization (same as your original code)
        System.setProperty("VLC_PLUGIN_PATH", "C:\\Program Files\\VideoLAN\\VLC\\plugins");
        File vlcInstallPath = new File("C:\\Program Files\\VideoLAN\\VLC");
        NativeLibrary.addSearchPath(RuntimeUtil.getLibVlcLibraryName(), vlcInstallPath.getAbsolutePath());
        Native.loadLibrary(RuntimeUtil.getLibVlcLibraryName(), LibVlc.class);
        LibXUtil.initialise();

        MediaPlayerFactory mediaPlayerFactory = new MediaPlayerFactory();
        EmbeddedMediaPlayer mediaPlayer = mediaPlayerFactory.newEmbeddedMediaPlayer();

        // Add a media event listener to handle media preparation
        MediaEventListener mediaEventListener = new MediaEventAdapter() {
            @Override
            public void mediaParsedChanged(MediaPlayer mediaPlayer, boolean newStatus) {
                if (newStatus) {
                    // Convert minutes to milliseconds
                    long startTimeMs = START_MINUTE * 60 * 1000;
                    // Set the playback start position
                    mediaPlayer.setTime(startTimeMs);
                    // Start playing
                    mediaPlayer.play();
                }
            }
        };
        mediaPlayer.addMediaEventListener(mediaEventListener);

        // Replace with your video file path or stream URL
        String mediaPath = "path/to/your/video.mp4";
        // Load the media (this triggers the mediaParsedChanged event when ready)
        mediaPlayer.prepareMedia(mediaPath);

        // Keep the application running (adjust as needed for your use case)
        Thread.currentThread().join();
    }
}

Key Notes: #

• prepareMedia vs playMedia: Using prepareMedia lets us wait for the media to be parsed before seeking, which ensures the seek operation works reliably.
• setTime() vs setPosition(): setTime() uses absolute milliseconds, perfect for specifying a minute mark. If you wanted a percentage of the video instead, use setPosition() (values from 0.0 to 1.0).
• Error handling: You can add checks to ensure startTimeMs doesn't exceed the video's total duration—use mediaPlayer.getLength() after the media is parsed to get the total runtime.

内容的提问来源于stack exchange，提问作者Kev