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refs:WALT
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) sorted by null
/external/walt/
README.md
0
##
WALT
Latency Timer ##
5
* [Post about
WALT
on Android Developers Blog](http://android-developers.blogspot.ca/2016/04/a-new-method-to-measure-touch-and-audio.html)
6
* [Instructional videos showing how to use
WALT
](https://www.youtube.com/playlist?list=PLd6Fi7WgXfcCEJg1FDqNCoQfpWo7W3J5a)
8
* Mailing list - [
walt
-discuss](https://groups.google.com/forum/#!forum/
walt
-discuss)
9
* Low-traffic mailing list for major announcements [
walt
-announce](https://groups.google.com/forum/#!forum/
walt
-announce)
11
WALT
is designed to measure the latency of physical sensors and outputs on phones and computers. It can currently perform the following measurements:
21
The
WALT
app for Android can be
22
[installed from Google Play](https://play.google.com/store/apps/details?id=org.kamrik.latency.
walt
)
[
all
...]
/external/walt/docs/
ChromeOS.md
1
## Using
WALT
on ChromeOS
3
WALT
can be used on ChromeOS in two different modes:
4
1. Via the [pywalt/
walt
.py](/pywalt/
walt
.py) command line script - for this mode refer to [pywalt/README.md](/pywalt/README.md)
5
1. Using the [
WALT
Android app](https://play.google.com/store/apps/details?id=org.kamrik.latency.
walt
) and
walt
.py script as a bridge
11
Copy the [pywalt/](/pywalt) directory from
WALT
repo to the Chromebook. One option is to download a repo tarball directly from GitHub:
14
wget https://github.com/google/
walt
/archive/master.tar.gz
16
cd
walt
-master/pywal
[
all
...]
ScreenLatency.md
3
WALT
can detect when screen changes color between white and black using a photodiode.
5
![Photo of bottom side of
WALT
](WALT_bottom_view.png)
9
WALT
Android app uses View.setBackgroundColor to change the color and reports the time from the beginning of the next frame rendering until the screen changes physically.
13
Example of screen brightness as a function of time during transition from black to white (blue line) and from white to black (green line) on Nexus 5X. The horizontal lines show the thresholds used by
WALT
for timing the transition (see #80).
29
All measurements below were taken with the device set to max brightness and
WALT
positioned in the middle of the screen.
AudioLatency.md
3
Audio output latency as measured by
WALT
is the time that passes from the moment an application
22
WALT
app follows this pattern.
25
[player callback](https://github.com/google/
walt
/blob/v0.1.6/android/
WALT
/app/src/main/jni/player.c#L107)
26
and the latency reported by
WALT
app is the time from the
27
[Enqueue() call](https://github.com/google/
walt
/blob/v0.1.6/android/
WALT
/app/src/main/jni/player.c#L123)
28
until there is a detectable signal on the wire. Note that this does not include the time between the moment the app decided to output a tone until the Enqueue() call. This is somewhat counterintuitive but this time is deliberately omitted. In case of the
WALT
app code this time is likely be uniformly distributed between 0 and the length of the buffer (5 ms in case of Nexus 5) and therefore would contribute considerable variance but little interesting information if included in the reported latency.
32
[recorder callback](https://github.com/google/
walt
/blob/v0.1.6/android/
WALT
/app/src/main/jni/player.c#L345
[
all
...]
PrivacyPolicy.md
0
##
WALT
Android App Privacy Policy
6
WALT
app processes all data locally on the Android device and does not transmit any information via the Internet,
12
WALT
app needs the Internet permission on ChromeOS devices where USB is not available to Android apps
Development.md
1
## Setting up for
WALT
Android app development
3
In general
WALT
Android app has no special requirements but since
WALT
usually takes up the only available USB connector on the phone, the typical development using ADB via USB becomes difficult. Below are some options to overcome this problem.
14
1. Use the hub to connect
WALT
, Ethernet adapter and whatever other USB peripherals you might want to test using
WALT
23
Since Android on ChromeOS has no access to USB, it requires a TCP bridge script implemented in [
walt
.py](/pywalt/
walt
.py). Detailed instructions in [Chromeos.md](Chromeos.md).
41
1. Run the
WALT
TCP bridge (more details [here](ChromeOS.md))
44
1. `python
walt
.py -t bridge`
DragLatency.md
5
For drag (or scroll) latency
WALT
uses a laser that shines across the touch device and hits a detector on the
35
The
WALT
app finds a shift _S_ such that the standard deviation of _y_( _t<sub>i</sub>_ + _S_) is minimal - that is the 'x' marks are as close as possible to a horizontal straight line on the graph below. The reported number is the average of the two time shifts calculated separately for the upper and the lower lines (corresponding to two sides of the finger).
TapLatency.md
6
WALT
uses a ?stylus? equipped with an accelerometer. The finger is imitated by a flat metal
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