We all love listening to music on our phones. In fact, listening to music, audiobooks, or podcasts regularly on our smartphones is probably one of the few things we all really share in terms of our usage patterns. The problem with listening to audio for extended periods, though, is that it can really put the hammer down on your battery life. Now, there's more than one reason for this - streaming high-quality audio over the web probably consumes more battery than the actual act of listening, but the power consumption of the processor while decoding that audio isn't negligible.

To address the latter issue, Google has introduced audio tunneling to DSP in Android 4.4. The premise is simple - instead of using the application processor to decode audio or respond to audio output requests, this responsibility is offloaded to the onboard DSP (digital signal processor). The DSP is much more efficient at such tasks than the CPU, and as such, Google estimates that the amount of power used playing back audio on your phone could decrease in excess of 50%! That's pretty impressive. In a local playback test (that is, non-streamed audio), the Nexus 5 extended its playback time from 30 hours without DSP tunneling to 60 hours with the new feature enabled.

The downside is that not all chipsets will support the feature, and that the Nexus 5 is currently the only device to take advantage of it. Google claims to be "work[ing] with our chipset partners" to get more devices on board, but we'll have to wait and see what that means for existing hardware. Given that the Nexus 5 uses a Snapdragon 800 chipset, it would seem plausible that DSP tunneling could come to some other S800-based products via an Android 4.4 OTA update, but it's still far from a given.

Be sure to checkout our other KitKat feature spotlights, more of which will be going up throughout the day.

Android Developers

David Ruddock
David's phone is whatever is currently sitting on his desk. He is an avid writer, and enjoys playing devil's advocate in editorials, and reviewing the latest phones and gadgets. He also doesn't usually write such boring sentences.

  • NinoBr0wn

    Well this is appreciated more than words can say. I didn't even know this feature was included.

  • baza58

    I want this so bad on my N4.

  • Pascal

    You are bringing more info than sites with N5.

    • Richard Yarrell

      Sounds great on paper. Let's see this in actual use on the Nexus 5 before jumping to any conclusion.

      • squiddy20

        Says the moron who claimed to "know" the specs of the S4 weeks before it was even unveiled and that it would be a huge hit, turned out to be totally false on all accounts, and still keeps saying this ridiculous BS.

      • BraydenLarwill

        Guy, you really need to jump out of the Samsung bandwagon. They aren't a perfect, all-knowing manufacturer. Their build quality is less than that of phones that came out 3+ years ago. They need to back away from the plastic and head towards new materials. Plus, the N5 is probably one of the phones to beat at the current time. The article above literally states, "In a local playback test (that is, non-streamed audio), the Nexus 5 extended its playback time from 30 hours without DSP tunneling to 60 hours meaning it's already been tested and is in effect. Actually read next time before insta-bashing it.

        • Just_Some_Nobody

          He can't stop. He's a troll. That's what he does.

      • MindFever

        You sir got burned and I find it pleasant to watch. Crawl back to that TouchWiz fetish dungeon of yours.

    • hyperbolic

      This is AndroidPolice not some AndroidSomethingSomething ;)

    • mikeym0p

      Well nothing brings more info than the changelogs.

  • John Daniel

    I just ordered my N5 and am a big Google music unlimited user so reading this but a huge smile on my face.

  • Simon Belmont

    All SoCs have a DSP chip. It's just a matter of leveraging them to get the desired effect that Google has done with the Nexus 5, so hopefully we see this on other SoCs.

    I actually find it amazing that this wasn't being done in the first place. I mean that's literally what DSP chips are for (among other things).

    • Mike Reid

      Too many different kinds of DSP/audio hubs/chips makes it hard.

      Easier just to run everything in software on AP.

      • Simon Belmont

        Yeah. That's why they need a hardware abstraction layer (HAL).

        Basically APIs that standardize how hardware is talked to no matter what chip is in there. Kinda like how DirectSound works with DirectX.

      • Stacey Liu

        The Nexus 4 and 5 use revisions of the same DSP though. Surely enabling it on the N4 wouldn't be that much extra work.

      • Just_Some_Nobody

        Not sure why it's hard. The chipmaker should give drivers to the OEMs. The OEMs could bake this in like they do all the other value-adds that they do. I think all of them until now with Google have just overlooked it.

  • Michael Bargerhuff

    couldn't be happier! One of the biiiiig things I do every day - and yes, big battery drain!

  • Bob G

    I get the sinking feeling that 80% of 4.4 will only apply to devices similar to the Nexus 5.

  • http://www.flickr.com/photos/77537273@N03/ Herman

    Now I can only hope for good audio output on the Nexus 5 as well, through the 3.5mm port.

    The only Nexus I owned was the Nexus 7, and I hope that was the exception of sound quality on Nexus devices. Its 3.5mm output was horrible compared to my Xperia S, and I'm not even that much of an audiophile.

  • enoch861

    I'm pretty sure other phones have been doing this. Having the processor do the decoding would mean that some audio fidelity is lost. Having the DSP do the decoding means you'd be limited to how good the DSP is. Thus many phones (Like some Samsung Galaxy phones and the LG G2) have to be using this kind of processing to be able to achieve the sound quality they're able to output; case in point the G2 even advertises 192/24 playback that actually sounds damn good.

    Thats my hypothesis at least. Good to see DSP decoding being supported in Android though!

    • basteagow

      There's no difference in quality (digital is all or nothing); only in efficiency and latency.

  • a67543210

    You will soon be seeing this update to an iPhone, near you

  • http://www.facebook.com/lucyparanormal Daniel Tiberius

    Glad to see they're still paying attention to this sort of thing. I probably listen to music on my Z Ultra more than I do anything else, so it's very important to me.

  • Stacey Liu

    What the hell? The Snapdragon S4 Pro should have a DSP too...

    There's absolutely no reason the Nexus 4 shouldn't get this feature too. Right now, music playback on the 4 consumes a lot of battery...I can't get anywhere near the 30 hour figure they're claiming for the Nexus 5 without DSP.

  • Drsela

    So... Samsung Galaxy S4 doesn't support DSP Tunneling? :/
    I feel like it's already outdated.. Snapdragon 800 seems way better..
    I love the Moto X feature, and phones with Snapdragon 600 would never get it..
    I envy Moto X and Nexus 5 users!

    • Laszlo Demeter

      Check Snapdragon page dude, S4 have the same DSP processor as Nexus 5. S600 have the same DSP add S800. There is still hope, if Google doesn't want to keep this features for itself

  • deltatux

    Last check the Nexus 4 also has a DSP, I'd be surprised if older Nexus devices wouldn't get DSP tunnelling support. Qualcomm integrates an audio DSP along with the audio codec that's built into the SoC for a while, so hopefully it can be backported to legacy Nexus devices.

  • mikeym0p

    I'm so glad they finally tackled audio power consumption. I highly doubted the S4 Pro needed to run the CPU at 300mhz to play an audio track while sleeping.

    • Hans Pedersen

      You should stop playing music while you're asleep. :)

      • mikeym0p

        Whyy youuu :)

  • Björn Lundén

    Qualcomm supports a feature called Tunnel Audio in CAF and we have had it working in CM for some time, though for a while it caused EQ not to work. I wonder how much that differs from the new 4.4 feature and if it can be adapted to work.

  • Ryan Stuckmaier

    Google's page says " For example, with audio tunneling, Nexus 5 offers a total off-network audio playback time of up to 60 hours, an increase of over 50% over non-tunneled audio."

    Which means it went from 40h to 60h (40h + 50%, or 20h). Your way, 30h to 60h, is 100% increase.

  • TestGuest

    Wouldn't the Moto X with its "always listening" feature have it activated as well?

  • Random!

    Too bad not even 32gb of local storage is enough to keep music locally. I'll still have to kill my battery life and data plan using streaming over cellular data.

    • Random!

      Truth be told, I'm keeping my N4 because prices in my country are outrageous. So I'm looking more at 13gb of actual storage.

  • vincentius phang

    will this work on N4 ?

  • ginobili1

    So does this mean that N4 won't get it this as it doesn't run S800?

  • jamesfuston

    This seems like a good enough post to necro and ask, who has some experience with the N5 now and how big of a difference does the DSP tunneling make? Specifically with cached (offline) All Access tunes?