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.
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  • Pirks - Monday, June 21, 2010 - link

    Isn't it? ;-)
  • sprockkets - Monday, June 21, 2010 - link

    Perhaps a jailbroken iphone user can let us know how well it is supposed to work LOL
  • ishbuggy - Monday, June 21, 2010 - link

    Yeah. I do it all the time on my jailbroken ipod 2g. Works like a charm. I have had it going for easily over 4 hours straight while playing games and browsing and it never stuttered or anything. Apple should look harder at some of the jailbroken software code I think.
  • CZroe - Wednesday, June 23, 2010 - link

    As a paid user of Music Controls, which adds backgrounding and locksceen control/art integration as well as miniplayer and a host of other touches (Next/Previous Track AVRCP being among my favorites), I can honestly say: Very well. I'm going to miss NT/PT on my motorcycle A2DP kit until there is an update or new program.
  • Inspector2211 - Monday, June 21, 2010 - link

    Quote: "...after about an hour of testing..."
    Quote: "...continued to get worse..."
    Quote: "...but Safari has begun crashing periodically while Pandora is playing..."

    'nuff said.
  • ImSpartacus - Monday, June 21, 2010 - link

    I've enjoyed the numerous, albeit short, articles that Anandtech has released lately, but this is going a little too far.

    I come to Anandtech for an intelligent, in depth review of various tech subjects, not this stuff. You can do better, AT!

    Anandtech != (Engadget, Gizmodo,...)
    Anandtech > (Engadget, Gizmodo,...)
  • Death666Angel - Tuesday, June 22, 2010 - link

    Well, if you think that these kinds of short articles (i.e. blogposts) are a reason that there will be less in depth analyses in the future, your comment is valid. However, I do not see it that way. This is more like a bread crumb AT gives us, to let us feel like part of the process and release early information they deem important to the issue. I like and support these short posts.
  • Lord Raiden - Tuesday, June 22, 2010 - link

    I agree with Spartacus, its been a while since dailytech got introduced, and the news were separated. Now it seems like the dailytech is leaking into the AT site competely.

    This just in,
    Blog posts,
    xbox dissected

    where are the serious articles that kept me going for hours when i was working night shifts 6 years ago? It was slow, but certainly AT has lost some of its vibe it once had.
  • nlr_2000 - Monday, June 21, 2010 - link

    Had the same problem on my iPod Touch 2G.
    When the screen dimmed it started skipping; all I did is touch the screen no skipping.
  • fynamo - Monday, June 21, 2010 - link

    Why is this on the front page???

    If this gets here, then why doesn't Anand report on the countless new Windows bugs that appear every day - and those have definite causes to point to as well, for crying out loud. Or some other random software?

    This isn't journalism. It's a couple of guys who haven't been getting enough sleep freaking out about their new favorite toy.

    Come on - get rid of this crap - put it on the blog where it belongs. I can't believe Anand is stooping to this type of "viral fanboyism."

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