# CreateStream has too big latency ( ~ 1 second )

**URL:** <https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623>\
**Category:** Unity\
**Tags:** unity, csharp\
**Created:** [February 24, 2025, 10:53am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623 "2025-02-24T10:53:49Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![xanaramus](https://avatars.discourse-cdn.com/v4/letter/x/b19c9b/32.png) [@xanaramus](https://qa.fmod.com/u/xanaramus)\
**Post date:** [February 24, 2025, 10:53am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/1 "2025-02-24T10:53:49Z")

</div>

FMOD Version: 2.02.19  
Unity Version: 2022.3.55f1  
Platform: Editor/Desktop

Goal: Is to use [Dissonance](https://placeholder-software.co.uk/dissonance/docs/index.html)  
with fmod programmer instrument instead of bus.

Additional information: Dissonance has paid asset to implement fmod playback with bus, and it works perfectly without latency. My implementation works, but has latency.

Issue: using `coreSystem.createStream` creates latency ~ 1 second, which exists even if you listen to yourself offline. Note even i remove programmer event, latency still exists.

Notes: I wont post code for AudioGenerator class as its a part of paid asset, but if needed i can upload it privately or the whole project.

```auto
        private AudioGenerator _generator;
        private int _sampleRate;
        private GCHandle _handle;
        private Sound _sound;
        private FMODSoundService _audioService;
        
        public Sound Sound => _sound;
        
        public override float Amplitude => _generator?.Amplitude ?? 0;

        protected override void OnEnable()
        {
            UnityEngine.Debug.Log("OnEnable");
            base.OnEnable();
            
            //Create Audio Generator
            _generator = new AudioGenerator(this);
            _handle = GCHandle.Alloc(_generator);
            
            var coreSystem = RuntimeManager.CoreSystem;
            coreSystem.getSoftwareFormat(out _sampleRate, out _, out _);
        
            var exitInfo = new CREATESOUNDEXINFO
            {
                numchannels = 1,
                format = SOUND_FORMAT.PCMFLOAT,
                defaultfrequency = _sampleRate,
                pcmreadcallback = SoundReadCallback,
                userdata = (IntPtr)_handle,
                cbsize = Marshal.SizeOf(typeof(CREATESOUNDEXINFO)),
                length = (uint)(_sampleRate * sizeof(float))
            };

            
            var res = coreSystem.createStream(string.Empty, MODE.OPENUSER | MODE.LOOP_NORMAL, ref exitInfo, out _sound);
            _sound.setUserData((IntPtr)_handle);
            UnityEngine.Debug.Log($"after userdata set sound: {_sound.handle.ToString("X")}");
            _sound.getUserData(out var testData);
            UnityEngine.Debug.Log($"after userdata set data: {testData.ToString("X")}");
            
            if(Check(res, "Failed to create FMOD sound") == false)
                return;
            
            //Play Sound
            coreSystem.getMasterChannelGroup(out var masterChannel);
            res = coreSystem.playSound(_sound, masterChannel, false, out var channel);
            UnityEngine.Debug.Log($"played sound {res.ToString()}");
            
            if(Check(res, "Failed to play FMOD sound") == false)
                return;
        }
  
        [AOT.MonoPInvokeCallback(typeof(SOUND_PCMREAD_CALLBACK))]
        private static RESULT SoundReadCallback(IntPtr sound, IntPtr data, uint datalen)
        {
            var soundDummy = new Sound(sound);
            soundDummy.getUserData(out var userdata);
            
            var length = datalen / sizeof(float);

            if (userdata == IntPtr.Zero)
            {
                FloatMemClear(data, length);
                return RESULT.OK;
            }

            // Extract a data source from the GC handle and copy the data into the DSP output buffer
            var ud = GCHandle.FromIntPtr(userdata);
            var audioGenerator = (AudioGenerator)ud.Target;

            // If the target is null clear the buffer to silence and early exit.
            if (audioGenerator != null)
            {
                return audioGenerator.GetAudio(data, length, 1);
            }

            FloatMemClear(data, length);
            return RESULT.OK;
        }

        private static bool Check(RESULT result, string message, bool err = false)
        {
            if (result == RESULT.OK)
                return true;

            const string fmt = "{0}. FMOD Result: {1}";
            if (err)
                Log.Error(fmt, message, result);
            else
                Log.Warn(fmt, message, result);

            return false;

        }

        private static void FloatMemClear(IntPtr buffer, uint length)
        {
            unsafe
            {
                var ptr = (float*)buffer.ToPointer();
                FloatMemClear(ptr, length);
            }
        }

        private static unsafe void FloatMemClear(float* buffer, uint length)
        {
            for (var i = 0; i < length; i++)
                buffer[i] = 0;
        }

```

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<div class="post-metadata">

**Author:** ![xanaramus](https://avatars.discourse-cdn.com/v4/letter/x/b19c9b/32.png) [@xanaramus](https://qa.fmod.com/u/xanaramus)\
**Post date:** [March 5, 2025, 9:12am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/2 "2025-03-05T09:12:28Z")

</div>

bump

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<div class="post-metadata">

**Author:** ![Leah\_FMOD](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/leah_fmod/32/3685_2.png) [@Leah\_FMOD](https://qa.fmod.com/u/Leah_FMOD)\
**Post date:** [March 6, 2025, 2:45am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/3 "2025-03-06T02:45:46Z")

</div>

Apologies for the delayed response.

After testing your code, edited to load a large float PCM file upfront and then stream it using `PCMREAD_CALLBACK`, I unfortunately haven’t been able to reproduce the latency you’re describing, which makes me think that the issue has to do with how `AudioGenerator` is handling its sample data.

That said, I’d recommend trying a few things on the FMOD side of things:

- Check that you haven’t set [`defaultDecodeBufferSize`](https://www.fmod.com/docs/2.02/api/core-api-system.html#fmod_advancedsettings_defaultdecodebuffersize) in the Core System’s Advanced settings to a value above the default, which could increase latency
- See whether creating a regular sound instead of a stream makes any difference - since you’re using `OPENUSER` and `PCMREAD_CALLBACK`, the functional difference between a stream and `OPENUSER` is somewhat negligible
- Try using `PCMREAD_CALLBACK` to stream a file from a buffer or from disk instead of `AudioGenerator` to see whether you can still reproduce the issue

Otherwise, could I get you to upload a stripped-down version of your project in which you can still reproduce the issue to your [FMOD User Profile](https://www.fmod.com/profile#uploads) for me to take a closer look at?

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<div class="post-metadata">

**Author:** ![xanaramus](https://avatars.discourse-cdn.com/v4/letter/x/b19c9b/32.png) [@xanaramus](https://qa.fmod.com/u/xanaramus)\
**Post date:** [March 10, 2025, 5:02pm UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/4 "2025-03-10T17:02:20Z")

</div>

@Leah_FMOD

Thanks for response!)

I have uploaded DissonanceFMODSoundIssue project to my profile.  
You should be able to reproduce issue by playing Offline scene.  
FMODEventPlaybackPrefab is implementation with sound which has ~1sec delay.  
FMODPlaybackPrefab is implementation with bus and has nearly no latency.  
Scripts are also in same folder.

I also have not changed any default settings for fmod, thanks!

 ![image](https://canada1.discourse-cdn.com/flex036/uploads/fmod/original/2X/e/ef8f997c758143b3cba36177012ce39e3c33e184.png)

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<div class="post-metadata">

**Author:** ![Leah\_FMOD](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/leah_fmod/32/3685_2.png) [@Leah\_FMOD](https://qa.fmod.com/u/Leah_FMOD)\
**Post date:** [March 18, 2025, 4:17am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/5 "2025-03-18T04:17:39Z")

</div>

Thanks for uploading your project!

The reason for the difference in latency is that Dissonance’s implementation uses a custom DSP, while yours uses a custom read callback. The DSP’s buffer size is the determined by the core system’s [DSP buffer size](https://www.fmod.com/docs/2.02/api/core-api-system.html#system_setdspbuffersize), which by default is 1024 samples. On the other hand, a custom read callback’s buffer size is determined by [`CREATESOUNDEXINFO.decodebuffersize`](https://www.fmod.com/docs/2.02/api/core-api-system.html#fmod_createsoundexinfo_decodebuffersize), which by default matches the [default decode buffer size set for the system](https://www.fmod.com/docs/2.02/api/core-api-system.html#fmod_advancedsettings_defaultdecodebuffersize). The system’s default decode buffer size is 400ms - at a sample rate of 48kHz this is 19200 samples, meaning it incurs 18.75x more latency than the DSP implementation.

The easiest fix is to specify a lower `decodebuffersize` in the sound’s `CREATESOUNDEXINFO`. If you specify a size matching the system’s DSP buffer size, you should observe latency roughly equivalent to the DSP implementation. You can grab the DSP buffer size with [`RuntimeManager.CoreSystem.getDSPBufferSize()`](https://www.fmod.com/docs/2.02/api/core-api-system.html#system_getdspbuffersize).

---

<div class="post-metadata">

**Author:** ![xanaramus](https://avatars.discourse-cdn.com/v4/letter/x/b19c9b/32.png) [@xanaramus](https://qa.fmod.com/u/xanaramus)\
**Post date:** [March 18, 2025, 2:11pm UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/6 "2025-03-18T14:11:35Z")

</div>

Lol it works like a charm

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<div class="post-metadata">

**Author:** ![Leah\_FMOD](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/leah_fmod/32/3685_2.png) [@Leah\_FMOD](https://qa.fmod.com/u/Leah_FMOD)\
**Post date:** [March 19, 2025, 1:45am UTC](https://qa.fmod.com/t/createstream-has-too-big-latency-1-second/22623/7 "2025-03-19T01:45:56Z")

</div>

Happy to hear!