VideoPlayer and OnAudioFilterRead()

Unity Engine
,
1

Hi,

Is it possible to feed the audio output of the Video Player to the OnAudioFilterRead() method? Or are they not compatible?

I had already implemented some audio processing via the OnAudioFilterRead() method, which worked when I assigned an audio clip to the audio source and added my processing script.

Now, I am trying to apply the same processing to the audio output of a VideoPlayer object. The VideoPlayer’s audio output mode is set to “Audio Source”, "Controlled tracks" = 1, I enabled the toggle button for “track 0”, and assigned the audio source from my previous implementation to the VideoPlayer’s audio source field. the audio output of the video is routed correctly to the audio source and all the inspector properties are applied correctly (i.e. output mixer routing, volume and spatial blend), but my OnAudioFilterRead() method is receiving an empty buffer.

I also tried adding the audio processing script directly to the VideoPlayer and setting the output mode to “direct” but the OnAudioFilterRead() method is not even being called.

2

What version of Unity are you using? I just tried routing a video’s audio through an AudioSource on the latest build and filters and OAFR are working as expected.
Could you provide code examples and screenshots of you VideoPlayer component setup?

3

I am using Editor 2022.3.12f1

Here is my Video Player component
9809838--1408875--upload_2024-5-2_13-50-46.png
*A different script sets the video URL on Start()

And here is the script on my Audio Source

public class GBRSourceProcessing : MonoBehaviour
{
    [DllImport("audioplugin_gbr")]
    private static extern void ingestCh(float[] inBuffer, int bufferLength, int numchannels, string streamID);
    public string selectedStreamID;
    void OnAudioFilterRead(float[] data, int channels)
    {
        int bufferLength = data.Length / channels;
        ingestCh(data, bufferLength, channels, selectedStreamID);
    }
}
4

Upon closer inspection, this is what I found:
If I run the project with the GBRSourceProcessing script enabled and insert a break point on line 8 of the code above, data only contains 0s (even after a couple seconds of video playback).

On the other hand, if I disable the GBRSourceProcessing script, run the project and enable the script after running, data has the right values and my script works as expected :eyes:

5

Can you try to do the same kind of test, but without the DllImport and just checking the content of data?

  • Without the DLL, component enabled from the start, what’s in data?
  • Without the DLL, component enabled later at runtime, what’s in data?

If you see the same thing happening (all-zero data vs expected data) then could you please submit a bug report with a simplified version of you project isolating this? It could indicate an issue around VideoPlayer and OAFR’s early calls from the audio thread.

In the case where you get the expected behaviour in both cases without the DLL, then we’ll dig deeper in that direction. It would not be the first time that something goes wrong in such a scenario.

P.S.: my colleague from the desk besides suggests you check channels for 0 values, just in case!

6

Without the DLL I get the same behaviour and channels = 2 so I have sent a bug report, thanks for your help!

1 Like
7

Hi @restreao_iis

Can you send me the id you got for the bug you submitted? Thank you!

8

Case IN-75697
Internal ID UUM-72367

1 Like