Play MP4 in mobile without sound

Development Audio
, , , ,
1

Hi guys,

I recently deployed a level to mobile Android. The level includes some MP4 movies which are mapped as materials onto some meshes (flat screens in the level). However, for some reason, when I deploy my package to mobile the sound of the MP4 is played even though I have chosen not to have a media sound file and do not have a sound cue in my level of that movie. I’ve also not selected a sound wave in my Media asset so there’s no reason why it should play the sound of the MP4. When I do a mobile (or regular) preview in the editor, the moview plays without sound, as I expected. When I deploy to the Android mobile, the sound is playing. How can I prevent this? Anyone has experience with mobile development? Thanks in advance.

2

Android always plays media audio via the OS sound mixer at the moment. The MediaSoundWave is completely ignored on Android as the Android Media API doesn’t have a way to extract the audio data yet.

You should be able to disable the audio by setting the selected audio track to INDEX_NONE (or -1).

3

Okay, that clarifies things. Thanks a lot for your help.

4

Hi gmpreussner,

I tried what you proposed by adding a Set Audio Track index node and set index to -1 (or INDEX_NONE which is converted to -1) with target being a variable of type Media Sound Wave (which defaults the sound wave of the movie).

139619-screen+index.png
139619-screen+index.png857×383 38.4 KB

This is added right after the Open Source node. Unfortunately, the sound is still playing when I launch it on smartphone. Am I doing something wrong and/or is there anything I can do else (apart from removing the sound from the MP4 upfront which doesn’t seem to be a real future-proof solution).

Thanks for your help.

5

Open sets the audio track to 0 and only valid indices for audio track >= 0 are passed to the player. You could make this change in AndroidMediaTracks.cpp to FAndroidMediaTracks::SelectTrack:

case EMediaTrackType::Audio:
	if (TrackIndex == INDEX_NONE)
	{
		JavaMediaPlayer->SetAudioEnabled(false);
		SelectedAudioTrack = TrackIndex;

		return true;
	}

	if (AudioTracks.IsValidIndex(TrackIndex))
	{
		if (!JavaMediaPlayer->SelectTrack(AudioTracks[TrackIndex].Index))
		{
			return false;
		}

		JavaMediaPlayer->SetAudioEnabled(true);
		SelectedAudioTrack = TrackIndex;
		InitializeAudioSink();

		return true;
	}
	break;

This should let -1 disable audio as expected.

6

I’ve fixed this for 4.17 (UE-45570).

7

Thanks for the workaround. I removed the sound from the mp4 upfront since I had to fix it urgently but hopefully your solution could still help someone else. I do hope they fix this problem though.