So why doesn't the iPhone record in stereo?

Discussion in 'iPhone' started by Bahroo, Oct 6, 2014.

  1. Bahroo macrumors 68000

    Jul 21, 2012
    I can't seem to find the answer to this question, why does it record audio in mono when it has 3 microphones? I don't get it
  2. 617aircav Suspended

    Jul 2, 2012
    Because they Apple didn't make it record in stereo. If they wanted it, they could have done it.
  3. dave1145 macrumors newbie


    Sep 29, 2014
    Yes, but WHY is that? What exactly is the reason?

    Before I got my iPhone 6, my last old phone was a 4 year old nokia and even that recorded in stereo, so it's kind of odd that the new iPhone 6 records in mono only.

    Also why are there 3 mics if it doesn't use them? Or does it use them but then mix 3 mics into 1 channel mono that seems pointless..

    The only thing I can think of is that they want to make the file size of the video files smaller by using mono instead of stereo. But this is pointless too as recording 1080p in 60fps will make huge files anyway. Still I just don't get it.
  4. scaredpoet macrumors 604


    Apr 6, 2007
    The three mics are used for noise cancellation. In phone-to-your-head-mode, the bottom mic is favored as the mic most likely to pick up your voice. The other two mics are used to sample the surroundings. If a sound is picked up on the bottom mic and on one of the two other mics, then it's processed out as noise. Your voice will be picked up loudest on the bottom mic but faintly on the other two, and so it will not be filtered out.

    In video/facetime mode, the same process is repeated, but the mic closest to the camera in use is given preference.

    In speakerphone mode, the top mic is usually given preference (though this can change depending on orientation).

    It's probably a more simple explanation: They expect that most people won't care about stereo recording, such that it wasn't worth the effort to engineer in stereo mic pairs for each of the three points that the phone can pick up audio. You would have to do all three if you decided to go all-in with stereo, because if you engineer stereo for just one point (say, the bottom), then when you hold the camera up to take a video, you're only recording sound from one side on both channels. DO it for the camera, and then it won't work for use as a voice recorder on a flat surface. etc.

    It might also interfere with the noise cancellation circuitry, and they may have felt that was more important than recording in stereo.

    Also, if someone really cares enough about recording in stereo, it's figured they can just get one of these or one of these and deal with the positioning limitations that come with it.
  5. Gmcube macrumors regular

    Jun 19, 2009
    I'm more annoyed that we still don't have stereo speakers. Even two mono ones would make it sound centered at least.
  6. Vertigo50 macrumors 65816


    Apr 11, 2007
    For good stereo recordings you need a good matched pair of mics. I don't think the mics are the same. Second, you would need them in similar locations on the phone, like the two ends. The three you have are at the bottom facing down, top forward and top backward. This is not good placement for separation. Lastly, it takes a really good recorder with good mics in an X/Y confoguration to make stereo recording sound separated.

    Add all that up and you can see why they figured it's not worth it.

    Here's what I mean by X/Y. See how big the. Mics are and the placement? And to me you just BARELY get usable results with this recorder.
  7. Winona Northdakota, Oct 6, 2014
    Last edited: Oct 6, 2014

    Winona Northdakota macrumors 6502a

    Dec 27, 2010
    So why doesn't the iPhone record in stereo?

    The iPhone can record in stereo just fine. You will need two microphones placed properly for stereo sound separation the iPhone's built in mics aren't designed for it, though the Røde stereo mic will do 24 bit 96k stereo recording:

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