Though the RC has been out for some time, and other builds before it, most of the multitasking features have gone relatively untested as they require applications to explicitly use APIs for background functionality. We were excited to play around with background audio today when Pandora released its iOS 4.0 tested, background-audio packing update. As far as we're aware, Pandora Radio is the first and only application in the app store right now supporting background audio playback.

The natural first test was to determine what impact background audio playback has on the battery life of our iPhone 3GSes. To do so, we loaded up our test page which cycles through a loop of article pages and galleries - simulating typical web browsing use - and left pandora playing in the background. Anand was testing over 3G, while I tested WiFi.

After about an hour of testing, I noticed that audio had begun skipping on my iPhone. To be completely honest, at first I thought this was part of the song I was listening to. Then I suspected some sort of buffering issue, but audio stuttering continued to get worse. Finally I decided to interrupt the test and try switching applications, when I noticed the phone had become unresponsive, rejecting all input. Mashing buttons did nothing, including the lock button. It looks like the following, and sounds like a techno song:

While I was sending the video to Anand, his iPhone 3GS running the exact same test but over 3G developed the same audio loop issue, forcing him to reboot. My iPhone eventually fixed itself after about 5 minutes of skipping, resuming audio playback and becoming responsive again. It's still playing right now, but Safari has begun crashing periodically while Pandora is playing in the background. Luckily, the audio has not started skipping again.
It’s difficult to tell at this point whether the issue lies with Pandora or iOS 4.0. Considering normal iPod playback works in the background just fine and possibly uses the same API, it’s entirely possible this a Pandora problem - especially considering it released just today, and this is a new feature. The other possibility is that the combination of our Safari page load test and Pandora in the background is using too much RAM, though iOS 4.0 is supposed to close background applications as the device gets low on RAM.
It also plausible that there's a problem with the scheduler in iOS 4.0. The combination of CPU load from our script, audio playback, and the fact that my iPhone eventually resumed being responsive leads us in that direction.
Either way, background Pandora streaming has become something of a poster child for demonstrating to end users that multitasking works - its execution needs to be flawless before the launch of iPhone 4.


View All Comments

  • ssj4Gogeta - Monday, June 21, 2010 - link

    It's the first time Apple has included mutitasking in their phone OS, so I think it's worth writing about. I'm sure they'll investigate further the AT way and post back the results. Reply
  • rocky12345 - Tuesday, June 22, 2010 - link

    Or how about the countless Apple OS bugs for that matter.

    -that is all-
  • Exelius - Monday, June 21, 2010 - link

    C'mon guys; this is a small software bug that will likely be fixed in a patch next week. Definitely not front page material; isn't this what dailytech or twitter are for?

    Maybe Apple set the bar too high on bug-free software (and honestly; their products are generally less buggy than any other tech company I can name) but this isn't real news.
  • bigboxes - Monday, June 21, 2010 - link

    AnandTech just sucks these days. Fluff stories and no real substance. Reply
  • piroroadkill - Tuesday, June 22, 2010 - link

    I disagree that AnandTech "sucks these days". They still have just as many in-depth articles about tech as they used to, but yes, there's a lot of this fluff inbetween those articles now, because it used to be that there wouldn't be updates on here every day, and people have short attention spans, they want to see new stuff flashing up in their face every second, because they're used to the verbal faeces shower that is the rest of the net - blogs, facebook, twitter

    I was fine with the old way really, but there's no way AnandTech has only bad articles now compared to a few years ago.
  • kmmatney - Monday, June 21, 2010 - link

    I'm guessing they are reporting this, since it is directly effecting their battery tests for the new iPhone OS and multitasking. Reply
  • Exelius - Monday, June 21, 2010 - link

    Go troll elsewhere. Reply
  • slyck - Monday, June 21, 2010 - link

    Well said. Reply
  • IndyJaws - Monday, June 21, 2010 - link that's clever! Bet you spell their competitor Micro$oft!

    I wanna be a technohipster just like you.
  • Passguide - Wednesday, June 23, 2010 - link

    <a href="" >650-251</a> Cisco Lifecycle Services for Advanced Unified Communications
    <a href="" >642-181</a> Cisco Unified Presence Design and Implementation

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