Audio Support

Vulkan Media Player provides comprehensive audio playback capabilities synchronized with video. Learn how to work with audio tracks and integrate them into your Unreal Engine project.

Overview

Audio support in Vulkan Media Player includes:

• ✅ Synchronized audio/video playback
• ✅ Multiple audio track support
• ✅ Integration with Unreal's audio system
• ✅ Audio submix support
• ✅ Volume and mute controls

Basic Audio Setup

Enabling Audio Output

When creating a Media Player:

1. Right-click in Content Browser
2. Select Media → Media Player
3. In the dialog:
   • ✅ Check Audio output Sound Wave asset
4. Click OK

This creates a Sound Wave asset (e.g., MP_MyVideo_Audio) that routes audio through Unreal's audio engine.

Playing Audio

Audio automatically plays when video playback starts:

// C++ - Open media source (audio plays automatically)
MediaPlayer->OpenSource(MediaSource);
MediaPlayer->Play();

Blueprint:

• Use Open Source and Play nodes - audio plays automatically

Audio Control

Volume Control

// Set volume (0.0 = silent, 1.0 = full volume)
MediaPlayer->SetVolume(0.5f);

// Get current volume
float Volume = MediaPlayer->GetVolume();

// Fade in audio
float CurrentVolume = 0.0f;
// In Tick or Timer:
CurrentVolume = FMath::Clamp(CurrentVolume + DeltaTime * 0.5f, 0.0f, 1.0f);
MediaPlayer->SetVolume(CurrentVolume);

Blueprint:

• Use Set Volume node on Media Player reference
• Value range: 0.0 to 1.0

Mute/Unmute

// Mute audio
MediaPlayer->SetVolume(0.0f);

// Or use native mute if available
// Check IMediaPlayer interface implementation

Blueprint Alternative:

Set Volume → 0.0  // Mute
Set Volume → 1.0  // Unmute

Multiple Audio Tracks

Some media files contain multiple audio tracks (e.g., different languages).

Detecting Audio Tracks

// Get number of audio tracks
int32 NumAudioTracks = MediaPlayer->GetNumTracks(EMediaPlayerTrack::Audio);

// Get audio track information
for (int32 i = 0; i < NumAudioTracks; i++)
{
    FText DisplayName = MediaPlayer->GetTrackDisplayName(EMediaPlayerTrack::Audio, i);
    FString Language = MediaPlayer->GetTrackLanguage(EMediaPlayerTrack::Audio, i);
    
    UE_LOG(LogTemp, Log, TEXT("Audio Track %d: %s (%s)"), 
           i, *DisplayName.ToString(), *Language);
}

Selecting Audio Track

// Select specific audio track by index
MediaPlayer->SelectTrack(EMediaPlayerTrack::Audio, 1); // Select track 1

// Get currently selected track
int32 CurrentTrack = MediaPlayer->GetSelectedTrack(EMediaPlayerTrack::Audio);

Blueprint:

• Use Select Track node
• Type: Audio
• Index: track number (0-based)

Audio Synchronization

Check Audio/Video Sync

Vulkan Media Player automatically synchronizes audio with video. To verify:

// Get video playback time
FTimespan VideoTime = MediaPlayer->GetTime();

// Audio is automatically synchronized to this time

Handle Sync Issues

If audio drifts out of sync:

1. Check frame rate: Ensure video frame rate is consistent
2. Check codec: Some codecs have better sync support
3. Driver update: Update GPU drivers to latest version

Audio Output Routing

Using Sound Wave Asset

The Sound Wave asset created with Media Player automatically routes audio through Unreal's audio engine:

// Get the Sound Wave asset
USoundWave* SoundWave = MediaPlayer->GetAudioComponent()->Sound;

// Apply audio effects, attenuation, etc. through standard Unreal audio system

Spatial Audio

To enable 3D spatial audio:

1. Add a Media Sound Component to an Actor
2. Set the Media Player reference
3. Enable Spatialization in the component settings
4. Position the Actor in 3D space

// C++ - Create and configure Media Sound Component
UMediaSoundComponent* MediaSoundComponent = CreateDefaultSubobject<UMediaSoundComponent>(TEXT("MediaSound"));
MediaSoundComponent->SetMediaPlayer(MediaPlayer);
MediaSoundComponent->bIsUISound = false; // Enable spatialization

Audio Formats

Supported Audio Codecs

Codec	Support	Notes
AAC	✅ Recommended	Best compatibility
MP3	✅ Supported	Common format
Opus	⚠️ Limited	Container-dependent
Vorbis	⚠️ Limited	Mainly in WebM/OGG

Recommended Settings

For best compatibility:

• Codec: AAC
• Sample Rate: 48000 Hz
• Channels: Stereo (2 channels)
• Bitrate: 192 kbps or higher

Advanced Audio Features

Audio Submix Integration

Route media audio through Unreal's submix system:

// C++ - Route to specific submix
UMediaSoundComponent* MediaSound = GetMediaSoundComponent();
if (MediaSound)
{
    MediaSound->SoundSubmixObject = MySubmix;
}

Use Cases:

• Apply audio effects (reverb, EQ)
• Mix with game audio
• Master volume control
• Audio ducking

Audio Callbacks

Monitor audio state:

// Listen for audio track changes
MediaPlayer->OnTracksChanged.AddDynamic(this, &AMyActor::OnTracksChanged);

void AMyActor::OnTracksChanged()
{
    // Refresh audio track list
    UpdateAudioTrackUI();
}

Troubleshooting

No Audio Output

Check List:

1. ✅ "Audio output Sound Wave asset" was checked when creating Media Player
2. ✅ Volume is not 0 (check with GetVolume())
3. ✅ Audio track exists in media file
4. ✅ Media Player is playing (not paused)

Common Issues:

Issue: Audio plays in editor but not in packaged game

Solution:

• Ensure media files are included in package
• Check audio codec is supported on target platform

Issue: Audio is crackling or distorted

Solutions:

• Check source audio bitrate (should be 192kbps+)
• Update GPU/audio drivers
• Reduce other audio processing load

Issue: Audio/video out of sync

Solutions:

• Re-encode video with proper audio sync
• Use constant frame rate video
• Check system performance (CPU/GPU load)

Audio Track Selection Not Working

Possible Cause: Media file doesn't contain multiple tracks

Verify:

# Use ffprobe to check audio tracks
ffprobe -v error -show_entries stream=index,codec_type,codec_name -of json input.mp4

Examples

Simple Audio Control UI

Blueprint Example:

1. Volume Slider:

   • Add Slider widget (0.0 to 1.0)
   • On Value Changed → Set Volume (Media Player)

2. Mute Button:

   • On Clicked → Branch (Is Muted?)
     • True → Set Volume(1.0)
     • False → Set Volume(0.0)

3. Track Selector:

   • Populate ComboBox with track names
   • On Selection Changed → Select Track

Audio Fade In/Out

// Fade In (in Tick function)
void AMyActor::Tick(float DeltaTime)
{
    if (bFadingIn)
    {
        CurrentVolume = FMath::Clamp(CurrentVolume + DeltaTime * FadeSpeed, 0.0f, 1.0f);
        MediaPlayer->SetVolume(CurrentVolume);
        
        if (CurrentVolume >= 1.0f)
        {
            bFadingIn = false;
        }
    }
}

// Start fade
void AMyActor::FadeIn()
{
    CurrentVolume = 0.0f;
    bFadingIn = true;
    MediaPlayer->SetVolume(0.0f);
    MediaPlayer->Play();
}

Best Practices

1. Always check audio track availability before selecting
2. Test on target platform - codec support varies
3. Use AAC codec for best compatibility
4. Monitor volume levels - avoid clipping
5. Implement fade in/out for smooth transitions

Next Steps

• Optimize Performance for audio/video playback
• Learn about Video Playback features
• Join our Discord for audio tips

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Need help with audio? Our Discord community is here to help!