Thursday, January 10, 2013

Smart cellphones as audio recorders - OK casual - Pro needs better

Continuing story .. smart cellphones as audio recorders.  We can download apps for most of them which record wav files.  Exciting idea - can this give us readily available high quality indie audio recorders?  I now think "no" as in not yet, or not with the phones we/friends/family currently have.

Story so far: Good early results with voice recording for film with the very low cost "Vodafone 858" - a Huawai Android.  More use as a backup recorder reveals electrical interference issues eg nearby electric fences.  Ref earlier post "Do Androids Dream of Electric Fences"  here:

New results:
I also find that high sound levels in music performances cause the little Android to distort, as in the app or the phone does not do automatic level setting or needs to do it better.

This last week I have been getting to know a Windows Phone 7.5 LG Quantum from the older lower end of the current Windows Phone system.  Similar result - OK for informal tests and student exercises but not quite good enough for serious indie production.  No result yet on electrical interference.  Loud sounds cause distortion like I observe with the Androids.

Most interesting Windows Phone result is that with a variety of recording software including an "Ultimate" app I paid for, the sample rate was always a relatively low 16khz with no controls for increasing that.  I am a computer programmer, mostly "Windows", so I set out to study microphone programming.  Interesting finding with wider implications is that the microphone behaviour is fixed and programming starts with the chips passing the software audio that is already digitised at 16khz.  So even with original programming with the "Dot Net" system I can do nothing about that 16khz.  The "xna" programming library of functions also offers no control over recording level.  I am intrigued though to discover in "OneNote Mobile" a notes sound recording function which gives very low quality but does seem to give an automatic recording level effect as in I speak very loudly into it and it copes.
QUESTION - Is microphone behaviour locked into the silicon chip design, or is there some deep low-level programming in the wider "Windows" outside of "Dot Net" that can change this?
QUESTION - If microphone behaviour is in the chip, would different brands of phones with different chips behave differently?  If you are reading this and you have a smartphone, you can use the blog messaging system to contact me and join in the test recording fun going on here.
THOUGHT - This experience suggests that Phone programming is about glueing together sub systems that are very much already programmed for us, and the internal-based parts of  "Apps" are really about alternative presentations of what is already there.  ie "Apps" are relatively easy and also limited - until we get into the area of doing more by connecting over the internet to a high-powered server to add more power to our problem-solving.

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