So yesterday we had a small get-together at my place, which gave me the opportunity to try something I’d been meaning to do for a while: build my own retroscope.
The idea is pretty simple: have a webcam record bits and pieces of a social event, then play them back on-the-spot a few minutes/hours later. I first heard about the concept from reading Nat Friedman’s blog entry from 2005 — if you read that, you see that he just hooked up a video camera to his TiVo. 7 years in the future, laptop webcams are ubiquitous and we have the awesome HTML5 tag, so I figured it would be easy to knock up something interesting in short order with zero custom hardware.
Having only remembered that I wanted to do this about 30 minutes before people were scheduled to start arriving, I didn’t have much time to do anything really perfect. I settled on using this little snippet from stackoverflow to generate short (5 second) movies on my laptop, then used scp to copy them over and display a montage of them in an auto-refreshing webpage on my “television” (which is a Mac-Mini connected to a large computer monitor). Despite being a total hack job, the end result generated much amusement. I think this is a bit different from what Nat originally did (it sounds from his blog like his retroscope played back longer segments), but I think the end result is actually a bit more fun.
Perhaps unfortunately, but probably ultimately for the best, only a few snippets from the actual night got stored away. One example is this gem:
(yes, that handsome fellow with the Pernot is me)
I thought it might be fun to release the slightly-cleaned up results of this experiment as opensource for others to play with, so I created a small project for it on github. Unlike the original version, no complicated scp scheme is required — I just reused Joel Maher’s most excellent mozhttpd library from mozbase to run a web server in the same process as the capture logic. All you need to do is run the server on a Linux machine with a webcam and connect to it with a web browser from any other machine on your local network.
Ok, this is somewhat mundane, but I’ve already had to do it twice (and helped someone do something similar on #mobile), so I figured I might as well blog about it for posterity.
For various automation tasks (notably the Eideticker dashboard and the cross-browser startup tests), we need to be able to launch an Android browser on the command line (via adb shell or our own custom SUTAgent). This is a bit of a black art, but you can find references on how to do this on stackoverflow and other places. The magic incantation is:
am start -a android.intent.action.VIEW -n <application/intent> -d <url>
So, for example, to launch Fennec, you’d run this on the Android command prompt:
am start -a android.intent.action.VIEW -n org.mozilla.fennec/.App -d http://mygreatsite.info
Ok, easy enough, but what if we want to launch a new browser that we just downloaded (e.g. Google Chrome)? Where do we get the application and intent names?
The short answer is that you need to reach into the apk and dig. 😉 There’s probably many ways of doing this, but here’s what I do (which has the distinct advantage of not needing to compile, download or run weird java applications):
Copy the apk onto your machine (the apk should be in /data/app: if you have a rooted phone, you should be able to copy that off to your machine).
Extract AndroidManifest.xml from the apk (it’s just a .zip) and run axml2xml.pl on it.
Examine the resultant xml file and look for the tag. It should have a property called which is the package name. For example:
We can see pretty clearly that the application name in this case is com.android.chrome (you can also get this by running ps when using the application)
- Finally, look for a tag called with an tag with as the android-name property. Scan up for the overarching activity tag, whose android-name property. This is the activity name. For example:
Likewise here we see that the activity name we want is .Main (which Android explicitly expands out to com.android.chrome.Main)
Armed with this information, you should now have enough information to launch the application. Furthering the example above, here’s how to start Chrome on Android via adb’s shell:
am start -a android.intent.action.VIEW -n com.android.chrome/.Main -d http://mygreatsite.info
Hope this helps someone, somewhere.
[ For more information on the Eideticker software I’m referring to, see this entry ]
tl;dr: You can now run the standard eideticker benchmarks easily on any Android phone without any kind of specialized hardware.
So Eideticker is pretty great at comparing relative performance between different browsers and generally measuring things in an absolutely neutral way. Unfortunately it’s a bit of a pain to use it at the moment to catch regressions: the software still has a few bugs and encoding/decoding/analyzing the capture still takes a great deal of time. Not to mention the fact that it currently requires specialized hardware (though that will soon be less of a concern at least inside MoCo, where we have a bunch of Eideticker boxes on order for the Toronto and Mountain View offices).
A few months ago, Chris Lord wrote up some great code to internally measure the amount of checkerboarding going on in Fennec. I’ve thought for a while that it would be a neat idea to hook this up to the Eideticker harness, and today I finally did so. After installing Eideticker, you can now run the benchmark on any machine against an arbitrary fennec build just by typing this from the eideticker root directory:
adb shell setprop log.tag.GeckoLayerRendererProf DEBUG
./bin/get-metric-for-build.py --no-capture --get-internal-checkerboard-stats --num-runs 3 nightly.apk src/tests/scrolling/taskjs.org/index.html
In return, you’ll get some nice clean results like this:
=== Internal Checkerboard Stats (sum of percents, not percentage) ===
[167.34348, 171.871015, 175.3420296]
Just to be sure that the results were comparable, I did a quick set of runs on the Eideticker machine in Mountain View with both internal checkerboard statistics gathering and HDMI capturing enabled.
While the results aren’t identical (we measure number of frames differently inside Fennec than we do with Eideticker, for one thing), they do seem roughly correlated. So go forth, benchmark and tweak! 😉
P.S. If you’ve been following mobile automation, you might be asking why I don’t just suggest running Talos and Robocop on your workstation. Can’t they do the same sorts of things? The short answer is that yes, they can, but unfortunately they’re much more involved to set up and use at the moment. Arguably they shouldn’t be, and this is something we (Mozilla tools & automation) need to work on. We’ll get there eventually (and help would be welcome!). For now, hacks like this should help with getting out the first release of Fennec by providing a fast, easy to use tool for bisection and analysis.
Build times for mozilla-central are a major factor in developer productivity. Faster build times mean more people using try (reducing breakage) and more fine-grained regression ranges (reducing the impact of breakages). As a side benefit, it allows us to avoid buying and maintaining more hardware (or put new hardware to better use). About a half-year ago, we set up a project called BuildFaster to try to bring these times down, setting the ambitious goal of getting build times (from checkin to tests done) down to 2 hours. We didn’t quite succeed, though we did make some major strides. As part of this project, we also developed a dashboard to track our progress and narrow down the major bottlenecks which were keeping up our build times.
Unfortunately, this dashboard went down earlier this year with the rest of Brasstacks and we hadn’t had the chance to bring it back up. I’m pleased to announce that thanks to Jonathan Griffin, it’s finally back online.
While no one is actively working on build performance at the moment (at least to my knowledge), it’s still useful to keep track of build times to make sure that we don’t regress. Anecdotally, it has seemed to me that the time needed to get results from try has been pretty stable over the last while, and this is borne out by the results:
As the cliche goes: no news is good news.
[ For more information on the Eideticker software I’m referring to, see this entry ]
Participated in an interesting meeting on checkerboarding in Firefox for Android yesterday. As a reminder, checkerboarding refers to the amount of time you spend waiting to see the full page after you do a swipe on your mobile device, and it’s a big issue right now – so much so that it puts our delivery goal for the new native browser at risk.
It seems like we have a number of strategies for improving performance which will likely solve the problem, but we need to be able to measure improvements to make sure that we’re making progress. This is one of the places where Eideticker could be useful (especially with regards to measuring us against the competition), though there are a few things that we need to add before it’s going to be as useful as it could be. The most urgent, as I understand, is to come up with a suite of tests which accurately represent the set of pages that we’re having issues with. The current main measure of checkerboarding that we’re using with eideticker is taskjs.org which, while an interesting test case in some ways, doesn’t accurately represent the sort of site that the user would normally go to in the wild (and thus be annoyed by). 😉
This is going to take a few days (and a lot of review: I’m definitely no expert when it comes to this stuff) to get right, but I just added two tests for the New York Times which I think are a step in the right direction of being more representative of real-world use cases. Have a look here:
The results here actually aren’t as bad as I would have expected/remembered. There amount of checkerboarding after a zoom out is a bit annoying (I understand this a known issue with font caching, or something) but not too terrible. Still, any improvements that show up here will probably apply across a wide variety of sites, as the design patterns on the New York Times site are very common.
(P.S. yes, I know I promised a comparison with Google Chrome for Android last time… rest assured that’s still coming soon!)
Just thought I’d mention this because I found it handy.
A while back AaronMT wrote up some clever instructions on taking Android screenshots by dumping the contents of ‘/dev/fb0’ and running ffmpeg on the results. This is useful, but you need to know the resolution of the device you have connected to pass the right arguments to ffmpeg. Wouldn’t it be better if you had just one script that would work for whatever device you had plugged in?
In fact, there is a way to do this using the monkeyrunner utility. Intended mainly as a tool for synthesizing input on Android (more on that some other time), you can also easily get a capture of the Android screen with its python/jython API (assuming you have the Android SDK installed). Here’s a quick script which does the job:
from com.android.monkeyrunner import MonkeyRunner, MonkeyDevice
if len(sys.argv) != 2:
print "Usage: %s <filename>" % os.path.basename(sys.argv)
device = MonkeyRunner.waitForConnection()
result = device.takeSnapshot()
Copy that into a file called capture.py (or whatever), then run it like so:
monkeyrunner capture.py screenshot.png<br />
And you’re off to the races! Nice screenshot, no utilities or non-essential command line arguments required!
(credit to this stackoverflow answer for the idea)
[ For more information on the Eideticker software I’m referring to, see this entry ]
Since my first Eideticker dashboard post was so well received, I thought I’d give a quick update on another metric that I just brought online: checkerboarding (a.k.a. the amount of time you spend waiting to see the full page after you do a swipe on your mobile device).
[ link to real thing ]
Unfortunately the news here is not as good as before: as the numbers indicate, the new Native Fennec currently performs substantially worse than the version in Android market. This is a known issue, and is currently being tracked in bug 719447.
Next up: Seeing how we do against Google Chrome for Android.
Over the last while, Clint Talbert and I have been working on setting up automatic mobile performance tests using Eideticker (a framework to measure perceived Firefox performance by video capturing automated browser interactions: for more information, see my earlier post).
There’s many reasons why this is interesting, but probably the most important one is that it can measure differences reliably across different types of mobile browsers. Currently I’m testing the old XUL fennec, the Android stock browser, and the latest nightlies.
I’m pleased to announce that the first iteration of the dashboard is available for public consumption, on my site.
The demo is pretty cheesey (just click on any of the datapoints to see the video capture), but nonetheless does seem to illustrate some interesting differences between the three browsers. The big jump in performance for nightly comes from the landing of the Maple branch, which happened earlier this week. Hopefully this validates some of the work that the mobile/graphics team has been doing over the past while. Exciting times!
For the last few days I’ve been experimenting with getting a Pandaboard running Android 4.0, continuing the work that Clint Talbert started in the fall to get these boards for use as a replacement for the Tegra in Mozilla’s android automation. The first objective is to get a reproducible build going, after that we’ll try to get some of our custom tools (SUTAgent & friends) installed by default.
So far this has been… interesting. Much as Clint did before, I thought I’d document some of the notes on what I did in the hopes that they’ll be helpful to other people trying to do similar things.
Getting things up and running is a two step process. First, you build the beast. This part is straightforward, just follow the instructions here:
At least the build part is more or less straightforward. Just follow the instructions here:
Note that you almost certainly want to build in the “eng” configuration, which is rooted and (apparently) has some extra tools installed.
Installing it is a little more tricky. The way they want you to do this is put the pandaboard into a special mode and copy the stuff you built onto an sdcard. Seem a little funny to you? Yeah, it does to me too. Why not just build an sdcard image directly?
Nonetheless, this is the officially supported way of imaging a pandaboard, so let’s just follow it until we can think of a better way of doing things. The instructions for doing this on the pandaboard are located in the source tree here:
These are mostly correct as far as I can tell, but there’s a few gotchas. First, you need to run the commands mentioned as root unless you’ve configured USB to be configurable by your user. Second, most of those commands are not in the path by default so you’ll need to specify the full path to e.g. the fastboot utility. The instructions here cover these exception cases: I recommend following them instead.
One thing which neither document mentions is that you really need to make sure your sdcard is wiped completely clean before using fastboot. The “oem format” step only recreates the partition table, it doesn’t delete any corrupted partitions. If you reboot while these are still in place, it will try to bring up your corrupted version of Android, not the fastboot console. I spent quite some time debugging why I couldn’t properly flash the operating system before realizing this. Easiest way to get around this is to dd
/dev/zero onto the sdcard before beginning the flashing process.
Also, while not strictly necessary to get something up and running, I recommend highly getting an HDMI monitor as well as a serialUSB adapter. The former is useful to see if your Android device actually successfully booted up, the latter is useful for debugging boot issues where you don’t get that far (the serial console is always available from boot).
So, after painfully learning about the above caveats, I have managed to get things mostly working. I can see the ICS homescreen on my attached HDMI monitor and interact with it if I attach a USB mouse. The one gotcha is that both ethernet and WIFI networking are totally broken. Plugging in an ethernet cable or connecting to a WIFI network seems to result in the machine randomly rebooting, with the logs saying nothing useful. Both of these things are ostensibly supposed to be working according to the latest I’ve read from Google so I’m not exactly sure what’s going on. Investigations will continue.
A few years ago, I fancied the idea of creating my own software consulting business. For some reason, I thought “Masala Labs” would be a cool and witty name for it (“masala” means spice mixture in Hindi, and who doesn’t like spicy things?), so I registered the domain along with the associated small business paperwork in Nova Scotia. I only ever had one client, and it was only a few months before I wound up joining a few of my colleagues in founding “The Navarra Group” (which is also now defunct, a story I will perhaps tell at another time), so it never got very huge.
Anyway, I still had my own domain, and I wanted to move my blog from livejournal, which was beginning to jump the shark. The masalalabs domain was mine, so why not use it? I created a wordpress blog, pointed my DNS registration at it, and started writing. This worked well for a while (names don’t really matter for random personal blogs), but lately I’ve been wanting to start a new project and “Masala Labs” doesn’t exactly seem like a winning banner for me to put it under.
So I’ve decided it’s time for a bit of a change. I just registered the swiss domain name ‘wrla.ch’, created a fancy new landing page, and made this blog its first “sub site”. More to come.
So, for all 20 of you who are subscribed to my doings, please update your links. For those of you using Google Reader / RSS, the new feed is at this URL. All the old masalalabs links should at least work until the domain expires in a few years, so there’s no huge rush. Then again, you’ll probably forget if you don’t do it now (and thus be deprived of my endless ravings about checkerboarding on mobile Fennec on Android), so why wait?