iPhone XS users: Do you feel stuttering?

Notes: This problem occurs not only on my apps.

I feel stuttering when using my app, KQ MiniSynth at higher performance on my iPhone XS, iOS 12.1.4.

Sample rate: 48,000Hz
Polyphony: 20
Buffer size: 64
Patch: FM Piano

With the same condition, there is no problem on iPad mini 3.

I also found the CPU load which is shown by AUM on iPhone XS is higher than that on iPad mini 3 when using various synth apps.
(Strangely, the load decreases when I add 4th Audio Unit to AUM.)

The issue occurs when buffer size is 64 on AUM.
For example, when using Bram bos Phasemaker as a Audio Unit with AUM, it stutters on iPhone XS but there is no problem on iPad mini 3.

This phenomenon is similar to the issue which occurred on iPad Pro 2018.
But people reported it has been solved.
https://forum.audiob.us/discussion/29769/gen-3-ipad-pro-users-have-you-noticed-significant-cpu-spikes

Am I alone?

I reported this issue to Apple 12 days ago but no meaningful response has come yet.

Comments

  • Hi Kira,

    That's strange, I noticed after updating KQ Minisynth to 2.0.6, the CPU usage more than doubled on my Air 1 and Mini 2. I wanted to email you earlier, but was busy.

    The AUM CPU meter doesn't show which cores are active, so if the high-performance cores are off (light load), then the power-saving low-performance cores will be working harder, resulting in higher CPU metering. Once the high-performance cores kick in (by adding more plugins), the CPU meter will drop.

    As far as the stuttering, does it happen when the KQ Minisynth GUI is closed?

    I'm not a dev, hopefully one of the other helpful devs will help you.

  • edited March 18

    That's strange, I noticed after updating KQ Minisynth to 2.0.6, the CPU usage more than doubled on my Air 1 and Mini 2. I wanted to email you earlier, but was busy.

    I briefly compared between ver 1.8.5, 2.0.5, and 2.0.6. The CPU load made a little difference.
    It is another problem. Please contact me privately.

    I want to talk about iPhone XS or other devices which have A12 processor. On my iPad mini 3 and iPad Air 2, the focused issue does not appear.

    The AUM CPU meter doesn't show which cores are active, so if the high-performance cores are off (light load), then the power-saving low-performance cores will be working harder, resulting in higher CPU metering. Once the high-performance cores kick in (by adding more plugins), the CPU meter will drop.

    I think so, too.

    > As far as the stuttering, does it happen when the KQ Minisynth GUI is closed?
    No.
    Deleted

    The issue occurs when buffer size is 64 on AUM.
    For example, when using Bram bos Phasemaker as a Audio Unit.
    I added the above information to the main post.

  • edited March 19

    Has anyone with an iPhone XS experienced stuttering when using either @RyoutaKira KQ MiniSynth or @brambos Phasemaker inside @j_liljedahl AUM when using a 64 sample buffer?

    @RyoutaKira is the developer of both KQ MiniSynth and KQ Dixie.
    I don't own an iPhone XS but possibly another forum member does and can help test. :wink:

    • Did @RyoutaKira mention that it only occurs when KQ Minisynth's GUI is open? EDIT: happens when the GUI is open and closed.
    • Does it only occur when using the iPhone XS' speakers?
    • Does it only occur when using an external audio interface? Which one?
    • Could it be related to audio sample rate?
    • Is True Tone enabled? Does it matter?
    • Is ProMotion enabled? (touch refresh/sample rate at 60hz or 120hz?) Does it matter?
    • Did @RyoutaKira mention that it only occurs when KQ Minisynth's GUI is open?

    No.
    I'm not good at English, so I misunderstood it.
    It happens whether KQ MiniSynth is running or not.

  • edited March 18

    On various Audio Units with AUM when buffer size is 64 and sample rate is 48k, it occurs on iPhone XS.
    For example, iceGear Kronecker Synthesizer, Laplace Synthesizer.
    On iPad Air 2, these Audio Units woks without a problem. But iPad mini 3 has a less performance.

    Even when buffer size is 256, it stutters with a specific condition on iPhone XS, it does not on iPad mini 3.
    Add KQ MiniSynth Audio Unit with Accordion patch and 20 polyphony to AUM,
    add Yamaha FM Essential, and play KQ MiniSynth, then noise occurs.
    And, when adding 2 more FM Essential, noise stops.
    (It seems to be switched to high-performance core.)

    And, I made a test app and it also stutters when polyphony increases on iPhone XS.
    Sometimes it stutters with extremely low polyphony on iPhone XS.
    With the same polyphony, it doesn't happen on iPad mini 3 and iPad Air 2.

  • Sounds like a CPU throttle issue for sure. This is a reason why I really hesitate to upgrade my 7 Plus. Any similar issue report with XR?

  • For developers, I have uploaded my codes to Github.
    https://github.com/KKQ-KKQ/audiotest-ios

    Please test with this tool.

  • @RyoutaKira said:
    Notes: This problem occurs not only on my apps.

    I feel stuttering when using my app, KQ MiniSynth at higher performance on my iPhone XS, iOS 12.1.4.

    Sample rate: 48,000Hz
    Polyphony: 20
    Buffer size: 64
    Patch: FM Piano

    With the same condition, there is no problem on iPad mini 3.

    I also found the CPU load which is shown by AUM on iPhone XS is higher than that on iPad mini 3 when using various synth apps.
    (Strangely, the load decreases when I add 4th Audio Unit to AUM.)

    The issue occurs when buffer size is 64 on AUM.
    For example, when using Bram bos Phasemaker as a Audio Unit with AUM, it stutters on iPhone XS but there is no problem on iPad mini 3.

    This phenomenon is similar to the issue which occurred on iPad Pro 2018.
    But people reported it has been solved.
    https://forum.audiob.us/discussion/29769/gen-3-ipad-pro-users-have-you-noticed-significant-cpu-spikes

    Am I alone?

    I reported this issue to Apple 12 days ago but no meaningful response has come yet.

    Personally the latest iOS version has undone all the 'storage" efficiency built into the last version.

    In lieu of shelving unused apps I end up with apps having super inflated sizes.

    My investigation has found some redundancy in the cloud features for apps over the course of a multi device network.

  • @RUST( i )K Yeah, Since iOS 12.1.3, my presets stored in iCloud dissapear and re-appear occasionally. Noticed that it happens mostly with the Sugar Bytes apps, but I do use those the most. Haven't figured it out yet.

  • Apple products with the A12 Bionic:
    iPhone XR (3GB RAM)
    iPhone XS (4GB RAM)
    iPhone XS Max (4GB RAM)
    Announced today: iPad Mini 5th Generation (? RAM)
    Announced today: iPad Air 3rd Generation (Supposedly 3GB RAM)

    So possibly 5 Apple products may have this issue? I don't want to sound like an alarmist but all of these recent stuttering, spiking CPU issues reminds me of the unavoidable high DPC latency with many Windows laptops. Even though any Windows laptop with a quad or hex core Intel CPU may seem ideal for audio and video work, most are permanently crippled due to high DPC latency and other issues caused by the motherboard, chipset, and attached hardware and poor drivers. That's why many of the 'boutique' resellers like Xotic PC will test DPC latency and publish the results right along with the hardware specs. Audio and video pros nagged them enough.

    Has anyone with an A12X (2018 iPad Pros) experienced this stuttering issue when running a 'CPU-light' synth in AUM with 64 sample buffer? The A12X has 2 additional high-performance cores versus the A12.

  • Yes I have that problems. Ipad pro 2018. Just thought I have a fast tablet but it is quite embarrassing for Apple.

    Bm3 kb1 plus sunrizer and gets pops and even crashes sometimes of bm3 audio engine. Ios 12.1.4

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