Author Topic: Measuring Guitar FX Audio / MIDI / iPad Latency - How?  (Read 2828 times)

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Offline Ringleader

Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« on: June 28, 2013, 08:03:16 AM »
Does anyone know how to measure audio latency on an iPad? Is there an app or combination of apps that will do this?

I used to use the Zoom G3 as my amp/cab/effects direct rig, but I've recently discovered that using my Zoom G3's amp sims (no cab) into Ampkit's cab sims (no amp) sounds waaaayyy better. The downside is that I am now noticing a bit of latency. I am curious how many ms of latency there is in the entire audio path from guitar input to monitor output. I would like to be able to measure the latency with various different methods of getting audio in and out of the iPad to compare them. Anyone know of a relatively easy way to do this?
« Last Edit: August 04, 2016, 10:52:09 PM by Elantric »

Offline Elantric

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #1 on: June 28, 2013, 08:39:23 AM »
1 ) I use a separate stereo audio recorder. I like the Zoom H4N, or an old Iphone4 with Fostex AR4i Audio interface and an IOS audio recording app like Refire or White recorder.


2 ) Left channel is Audio output from a headstock mounted piezo clip on pickup typically sold as an accessory for Peterson Strobe tuners. This provides immediate response from your guitar.

Peterson TP-3 Tuning Pickup
http://www.amazon.com/Peterson-TP-3-Tuning-Pickup/dp/B000NKKHVE/ref=sr_1_2?ie=UTF8&qid=1418052095&sr=8-2&keywords=peterson+tuner+clip





 Left Channel audio will be used as the Master timing reference.

3 ) Right channel is output audio from your "unit under test"

4 ) After making the 1 minute recording of your playing, load resulting Stereo Wave file in WaveLab or Soundforge and zoom in and look at the Left Channel. Use this Left Channel audio (from the headstock piezo pickup) as a reference to measure the Right Channel's  "unit under test" millisecond(s) offset delay. 
This is your latency.
The above strategy can be employed to measure any latency of any DSP guitar gadget or full rig.


** Note if you want higher accuracy  - replace the stereo audio recorder from step #1 with a dual trace storage oscilloscope

« Last Edit: June 21, 2017, 01:55:54 PM by Elantric »

Offline Ringleader

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #2 on: June 28, 2013, 09:19:37 AM »
Thanks Elantric. Interesting idea about using the clip on piezo - I wouldn't have ever thought to do that. I'll give what you suggested a try.
« Last Edit: December 08, 2014, 09:25:19 AM by Elantric »

Offline jassy

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #3 on: June 29, 2013, 05:31:56 PM »
And the resulting latency was?
I have curiosity about what latency can be achieved with the Ipad.
Anyone measured it?
« Last Edit: December 08, 2014, 09:25:48 AM by Elantric »

Offline Elantric

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #4 on: January 03, 2014, 07:21:44 PM »
Quote
And the resulting (iPad Audio ) latency was?

It Really depends on the IOS App, and what hardware version iPad and IOS version too.

For example with Positive Grid's "Bias" amp sim, and "ultra low latency" enabled, my iRig Pro running 24 bits @ 44.1kHz on my iPad Air running IOS 7.0.4 achieves around 8-10 milliseconds latency.

Quote
I use a separate stereo audio recorder. I like the Zoom H4N, or an old Iphone4 with Fostex AR4i Audio interface and an IOS audio recording app like refire or white recorder.

Left channel is Audio output from a headstock mounted piezo clip on pickup typically sold as an accessory for Peterson Strobe tuners. This provides immediate response from your guitar. This audio will be used as the Master timing reference.

Right channel is output audio from your "unit under test" (iPad Air running Bias)

After making the 1 minute recording of your playing, load resulting Stereo Wave file in WaveLab or Soundforge and zoom in and look at the Left Channel. Use this audio from the headstock piezo pickup as a reference to measure the millesecond(s) offset of the delayed "unit under test" processed Right Channel.  This is your latency.

The above strategy can be employed to measure any latency of any DSP guitar gadget or full rig.
« Last Edit: March 08, 2017, 01:15:04 PM by admsustainiac »

Offline Elantric

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #5 on: December 31, 2014, 05:45:22 PM »
A few of us are using and IOS app called "AUD-1" to accurately measure latency of IOS Audio Interfaces

http://www.aud1.com/
Assistive Listening Software

AUD-1 is a mobile app designed to intelligently modulate the loudness of the sonic environment for the hearing-impaired user. Enhancements in both comfort and clarity are achieved using research-driven signal processing. AUD-1 pushes the boundaries of assistive listening software, giving the user fine-grained, yet intuitive control over the sound shaping options.

screenshot   The app processes sound received by the microphone in real-time, then delivers the processed sound via headphones. Advanced connectivity options allow the user to customize the solution to their needs by optionally combining various audio hardware. The BioAid research algorithm forms the core of AUD-1’s processing strategy. AUD-1 is the evolution of mobile-platform assistive listening software, providing numerous advanced features that were requested for inclusion by users of the original BioAid app. No other assistive listening software currently provides either the depth of user control, or the sophistication of the sonic processing.
AUD-1 features:

Dual BioAid algorithm technology, allowing settings for each ear to be adjusted independently.
Advanced connectivity options, allowing use of high quality audio peripherals to improve sound quality.
Stereo linkage technology to preserve spatial cues when the app is used with stereo input hardware.
Fine grain control over the dynamic range of the processed sound.
High optimization for extremely low processing delay.
Automatic storage of preferred settings, even if the device runs out of power.
Adjustable input and output gain controls to fully utilize the dynamic range of the device.
Detection of accidental removal of headphones, preventing annoying feedback in public places.








« Last Edit: December 31, 2014, 06:09:07 PM by Elantric »

Offline admsustainiac

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #6 on: March 04, 2016, 01:33:12 PM »
https://www.usb-audio.com/latenc-o-meter/
Ploytec Latenc-o-meter

Latency Tester / Delay Meter


Pricing: Latenc-o-meter EUR 199.00 including shipment.


Here you can order the Ploytec Latenc-o-meter, a unique tool for finding the truth about latency.

The unit generates a "click" signal on its analog output (the red cinch connector) and waits until it returns on the input (the black cinch connector).

In the meantime it samples that input on its A/D converter running at 100kHz samplerate in order to get this amazing accuracy: The measurement range goes from 0.01ms to 999.99ms!

The red button switches it on while pressed, new clicks are generated every few seconds. It runs from a 9V battery which is easy to replace (but should last for ages depending on your application).

We use it for our development of external USB soundcards and drivers, but there's tons of further applications including checking your studio setup, testing digital audio equipment and last not least VoIP.

Pricing: EUR 199.00 including shipment. If you order from a non-European Union country there might be additional taxes charged by your national customs.

In the EU, you have the legal right to cancel your order (and return the unit) anytime within 14 days after ordering.

Estimated delivery time: Typically we ship on the day you order, max. 3 days. Your credit card will be charged on the day we ship the unit.


Offline Elantric

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #7 on: August 04, 2016, 10:53:23 PM »
https://expressiveelectronicsformusicians.com/our-products/midi-latency-analyser









MLA - MIDI Latency Analyser V2
Version-2 of this free software is vastly more capable than version-1. It still fulfills its original function of computing the average round-trip latency of synth audio when dubbing a MIDI'd synth to an audio track, but now it can also isolate timing problems to reveal the various causes, whether they be:
the transmitted MIDI clock or note data,
slow or jittery synth response, or,
slave devices bad at synchronising to MIDI clock.
Recorded synth is late compared to its MIDI track
Lagging audio
Free Downloads

Windows Version 2.1.1



Intel Mac Version 2.1.1


Software screen-shot
MLA screen
Using the software
Features numbered in the above screen-shot
This is the Show Help button. Click on this followed immediately by an on-screen control to bring up the help text for that control.

This button appears after MIDI bytes have been decoded from the loaded recording. Click on this to save a new wave-file containing blips that highlight the clocks, active-sensing and note data. You can then import the file into your DAW for viewing alongside the source MIDI track that produced it, and any other analysis waves you are interested in. Figures 1, 2 & 3 illustrate an example. Figure 1 shows how to prepare the MIDI track that will provide the notes for testing your system. Figure 2 labels the various parts of a blip-wave and includes a legend to explain the meanings of the blips. Figure 3 details the exact positioning of the blips relative to the recorded signals.

Up to four histograms will appear after the loaded recording has been analysed. The Synth's Own Jitter Distribution will appear only if both MIDI note data and synth audio tracks are analysed. The numbers indicate the dividing boundary between the outlier columns and the main columns.

Up to four Save As Wave buttons will appear after the loaded recording has been analysed, one for each Jitter Distribution histogram and its associated milli-seconds RMS text-box. The waves reveal whether the latency variation that resulted in the RMS value and the histogram shape was a high-frequency random jitter or whether it was a cyclic drifting of tempo. When the wave is above centre the notes or clocks are rushing earlier than average, and when the wave is below centre they are dragging later than average.

You can choose the horizontal scale of the histograms from this pull-down menu. It has no effect on the amplitude of the jitter waves produced when the buttons labeled "4" are clicked. When set to "Normalised individually" as shown in the screenshot, the outlier boundary numbers on the histogram scales reveal the size of the worst errors.

When you do a round-trip analysis to determin the number of samples offset to enter into your DAW's latency compensation setting, you should record synth attacks to a mono wave-file at the same sample-rate as your music session.

This is the status bar, and it will occasionally show information about what the software is currenly doing.

Capturing the MIDI signal
If all you want is to compensate for Synth Round-trip Latency, or to measure tempo, then you do not need to capture the MIDI signal. (You can simply record mono files of synth attacks just as you did with version-1, but now at any tempo.) However, in order to analyse extra information besides tempo and Synth Round-trip Latency, it will be necessary to record the MIDI signal's waveform as audio. A special adaptor is required to do this. Here is the schematic so that you may build the adaptor.
Getting started
First, it is important to understand where the MLA software fits within the scheme of things. To help illustrate this, here is a concept diagram, which essentially is a map. Your studio may not have all the physical and abstract things illustrated in the diagram, but don't worry: just as a road-map shows you places that you could visit if you chose to, this concept diagram reveals what options are available to you as you plan your "analysis journey."

Version-1 of this software has a fast algorithm to extract synth attacks from a recording, but it reported spurious attack errors when it encountered sluggish and bumpy envelopes. The recommended work-around for that problem was to slam the audio hard past 0 dBFS. Also, version-1 was restricted to one specific tempo.

The new algorithm used in version-2 is a lot slower at its job, but it works at any tempo, and is now able to accurately detect the very onset of a note's attack, even when it is a bit sluggish and bumpy. The ironic thing is that slamming too far above 0 dBFS now makes its job harder instead of easier. It is recommended that you record synth audio and MIDI signals at a peak level of between -1 dBFS and -5 dBFS.

Any time that the MIDI waveform is recorded, it is vital that the recording be done at 96,000 samples per second.

The cause of latency and jitter
A computer has to share its time among many tasks such as processing its mouse and keyboard data, updating the screen, performing DSP, sending MIDI, writing audio to its hard-drive, etc. Synths and samplers also have computer processes being executed inside them. Moving between the various software processes takes a tiny bit of time, so sometimes the MIDI ports are left waiting to be emptied and filled.
Two MIDI ports that sometimes have to wait
Latency cause
Referring to the illustration above, we cannot do much about processes at B. Unless a synth manufacturer provides a firmware update for your instrument that changes how its internal computer talks to its MIDI ports, you are stuck with whatever latency and jitter it has. The news is better concerning software processes at A, though. You can try different drivers, different interfaces, and you can disable unnecessary software that could be running in the background.


Offline Elantric

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #9 on: March 07, 2017, 12:27:42 PM »
Here's  a couple apps for for determining Audio  Latency  in MS Windows   / OSX


Quote
RTL UTILITY
RTL Utility is a tool for measuring the Round Trip Latency of your DAW and audio interface. The utility has been developed for the Low Latency Performance test at dawbench.com.

Balanced jack
Loopback patching is required
 

When your DAW sends data to your audio interface for playback, it doesn’t send a continuous stream of data one bit at a time. What it does is fill up a section of RAM called a buffer and sends that in one message when it is ready. Before sending the next message it has to fill the buffer again. This wait time introduces a latency, or delay, between something happening in your DAW and when you actually hear it.

When you are recording, the audio interface buffers and sends data to your DAW in a similar fashion. This introduces latency into your recordings.

If you send a signal from your DAW, out through the audio interface and back in via a loopback patch, then there will be a round trip latency which is the sum of the output and input delays. This is the RTL.
http://www.oblique-audio.com/free/rtlutility


---
Quote

History :.
            
This project has been a work in progress since around the start of August 2005, I decided to develop a suite of test sessions that were not based on the typical Dyno Run / CPU readout style of benchmarks that have been the norm previously.

The Project has evolved over the years to now include dedicated benchmark sessions for Nuendo / Cubase , SONAR and Protools as well as the DAWbench DSP Universal benchmark , which also includes Reaper , StudioOne, and Logic as well as the applications listed previous.

    
The tests and ongoing threads have definitely uncovered a large number of variables that can be explored , we have learned a great deal in the process , and I have no doubt that the collective and ongoing discussion can be a benefit to all.

The Project was also featured in an article in Sound On Sound in July 2006 Here , and has been featured in many subsequent articles relating to DAW performance.



    
I have configured a dedicated forum for not only the existing test sessions, but all of the future benchmarks that are currently in development.

If you can contribute in any way, please feel free to contact me via email, or register and post in the forum.

Vin Curigliano
AAVIM Technology

 
http://www.dawbench.com/benchmarks.htm


and determine your bottlenecks with this

Quote
The DPC Latency Checker tool
If any kernel-mode device driver in your Windows system is implemented improperly and causes excessive latencies of Deferred Procedure Calls (DPCs) then drop-outs will probably occur when you use real-time audio or video streaming applications. For an explanation of this effect see Background information below.
 
The DPC Latency Checker tool determines the maximum DPC latency that occurs on your Windows system and thus enables you to check the real-time capabilities of your computer. DPC Latency Checker works independently of any external hardware. Using this tool may be helpful in the following situations:
You experience interruptions (drop-outs) in a flow of data processed in real-time, for example an audio stream, video stream or a sequence of measuring data, and you want to find out the reason for this problem.
You want to verify that your Windows system is configured properly so that it is capable of handling real-time data transfer before you install the corresponding streaming application.
You want to check if a particular computer system is suitable for streaming applications, for example before you buy this system.
For more information on the Deferred Procedure Call mechanism and how an excessive DPC latency will affect a streaming application see Background information below.
http://www.thesycon.de/eng/latency_check.shtml



https://www.gearslutz.com/board/11591001-post771.html


« Last Edit: March 08, 2017, 01:19:03 PM by admsustainiac »

Offline admsustainiac

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #10 on: June 02, 2017, 05:27:35 PM »
http://superpowered.com/latency
iOS and Android Audio Latency Test App
Measure the performance of any mobile device immediately with the Superpowered Mobile Audio Latency Test App for Android and iOS.
Low round-trip audio latency is a strong indicator of how well any mobile device is optimized for professional audio. Lower latency confers significant benefits to users of all sorts of apps like games, augmented hearing apps, VOIP and other interactive apps.
[For practical tips on dealing with latency, Android developers please also see Android Audio Low Latency Primer.]
(Please see Android’s 10 Millisecond Problem: The Android Audio Path Latency Explainer and the more recent Rebooting Android's 10 Millisecond Problem: Audio Latency Improvements in Android 6.0 Marshmallow for more background on the importance of low-latency audio and business ramifications.)



https://github.com/superpoweredsdk

Offline Hurricane

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #11 on: July 13, 2017, 04:02:00 PM »
https://expressiveelectronicsformusicians.com/our-products/midi-latency-analyser


(Image removed from quote.)

(Image removed from quote.)

(Image removed from quote.)


MLA - MIDI Latency Analyser V2
Version-2 of this free software is vastly more capable than version-1. It still fulfills its original function of computing the average round-trip latency of synth audio when dubbing a MIDI'd synth to an audio track, but now it can also isolate timing problems to reveal the various causes, whether they be:
the transmitted MIDI clock or note data,
slow or jittery synth response, or,
slave devices bad at synchronising to MIDI clock.
Recorded synth is late compared to its MIDI track
Lagging audio
Free Downloads

Windows Version 2.1.1



Intel Mac Version 2.1.1


Software screen-shot
MLA screen
Using the software
Features numbered in the above screen-shot
This is the Show Help button. Click on this followed immediately by an on-screen control to bring up the help text for that control.

This button appears after MIDI bytes have been decoded from the loaded recording. Click on this to save a new wave-file containing blips that highlight the clocks, active-sensing and note data. You can then import the file into your DAW for viewing alongside the source MIDI track that produced it, and any other analysis waves you are interested in. Figures 1, 2 & 3 illustrate an example. Figure 1 shows how to prepare the MIDI track that will provide the notes for testing your system. Figure 2 labels the various parts of a blip-wave and includes a legend to explain the meanings of the blips. Figure 3 details the exact positioning of the blips relative to the recorded signals.

Up to four histograms will appear after the loaded recording has been analysed. The Synth's Own Jitter Distribution will appear only if both MIDI note data and synth audio tracks are analysed. The numbers indicate the dividing boundary between the outlier columns and the main columns.

Up to four Save As Wave buttons will appear after the loaded recording has been analysed, one for each Jitter Distribution histogram and its associated milli-seconds RMS text-box. The waves reveal whether the latency variation that resulted in the RMS value and the histogram shape was a high-frequency random jitter or whether it was a cyclic drifting of tempo. When the wave is above centre the notes or clocks are rushing earlier than average, and when the wave is below centre they are dragging later than average.

You can choose the horizontal scale of the histograms from this pull-down menu. It has no effect on the amplitude of the jitter waves produced when the buttons labeled "4" are clicked. When set to "Normalised individually" as shown in the screenshot, the outlier boundary numbers on the histogram scales reveal the size of the worst errors.

When you do a round-trip analysis to determin the number of samples offset to enter into your DAW's latency compensation setting, you should record synth attacks to a mono wave-file at the same sample-rate as your music session.

This is the status bar, and it will occasionally show information about what the software is currenly doing.

Capturing the MIDI signal
If all you want is to compensate for Synth Round-trip Latency, or to measure tempo, then you do not need to capture the MIDI signal. (You can simply record mono files of synth attacks just as you did with version-1, but now at any tempo.) However, in order to analyse extra information besides tempo and Synth Round-trip Latency, it will be necessary to record the MIDI signal's waveform as audio. A special adaptor is required to do this. Here is the schematic so that you may build the adaptor.
Getting started
First, it is important to understand where the MLA software fits within the scheme of things. To help illustrate this, here is a concept diagram, which essentially is a map. Your studio may not have all the physical and abstract things illustrated in the diagram, but don't worry: just as a road-map shows you places that you could visit if you chose to, this concept diagram reveals what options are available to you as you plan your "analysis journey."

Version-1 of this software has a fast algorithm to extract synth attacks from a recording, but it reported spurious attack errors when it encountered sluggish and bumpy envelopes. The recommended work-around for that problem was to slam the audio hard past 0 dBFS. Also, version-1 was restricted to one specific tempo.

The new algorithm used in version-2 is a lot slower at its job, but it works at any tempo, and is now able to accurately detect the very onset of a note's attack, even when it is a bit sluggish and bumpy. The ironic thing is that slamming too far above 0 dBFS now makes its job harder instead of easier. It is recommended that you record synth audio and MIDI signals at a peak level of between -1 dBFS and -5 dBFS.

Any time that the MIDI waveform is recorded, it is vital that the recording be done at 96,000 samples per second.

The cause of latency and jitter
A computer has to share its time among many tasks such as processing its mouse and keyboard data, updating the screen, performing DSP, sending MIDI, writing audio to its hard-drive, etc. Synths and samplers also have computer processes being executed inside them. Moving between the various software processes takes a tiny bit of time, so sometimes the MIDI ports are left waiting to be emptied and filled.
Two MIDI ports that sometimes have to wait
Latency cause
Referring to the illustration above, we cannot do much about processes at B. Unless a synth manufacturer provides a firmware update for your instrument that changes how its internal computer talks to its MIDI ports, you are stuck with whatever latency and jitter it has. The news is better concerning software processes at A, though. You can try different drivers, different interfaces, and you can disable unnecessary software that could be running in the background.

8)
Elantric :

Tried to install this on Win 10 a got a warning not to install ?  :o

HR

Offline admsustainiac

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #12 on: September 14, 2017, 02:30:45 PM »
Quote
Tried to install this on Win 10 a got a warning not to install ?  :o

Thats true  - and why I do not recommend using Windows 10 (because many apps I use remain incompatible )


« Last Edit: September 14, 2017, 02:35:58 PM by admsustainiac »

Offline admsustainiac

Re: Measuring Guitar FX Audio / MIDI / iPad Latency - How?
« Reply #13 on: October 31, 2017, 03:40:40 PM »
http://superpowered.com/latency
iOS and Android Audio Latency Test App
Measure the performance of any mobile device immediately with the Superpowered Mobile Audio Latency Test App for Android and iOS.
Low round-trip audio latency is a strong indicator of how well any mobile device is optimized for professional audio. Lower latency confers significant benefits to users of all sorts of apps like games, augmented hearing apps, VOIP and other interactive apps.
[For practical tips on dealing with latency, Android developers please also see Android Audio Low Latency Primer.]
(Please see Android’s 10 Millisecond Problem: The Android Audio Path Latency Explainer and the more recent Rebooting Android's 10 Millisecond Problem: Audio Latency Improvements in Android 6.0 Marshmallow for more background on the importance of low-latency audio and business ramifications.)

http://superpowered.com/android-audio-latency-problem-just-got-worse

https://github.com/superpoweredsdk

http://superpowered.com/android-audio-latency-problem-just-got-worse

 

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