I've been working with android audio recording for a while. As far as I know the only guaranteed supported recording sample rate is 44100Hz which means up to 22KHz of bandwidth.
This should be a "real" sampling rate, no upsampling on most devices. Did you try to set AudioRecord with 44.100Hz as sampling rate? Regards. Il 23/dic/2015 17:20, "Robert Scott" <[email protected]> ha scritto: > There is an audio recording problem with some devices, even newer ones. > The native audio recording sample rate appears to be a puny 8000 Hz, which > means it can only render frequencies up to 4000 Hz. This is a problem for > my piano tuning app which must detect frequencies above 4000 Hz. to tune > the top few notes. > > So far I have only gotten reports of this problem on certain models of the > LG G3 and the Nexus 7 (Asus). The worst part is these devices do not > return an error when we try to set up an audio input stream and request a > sample rate of 22050 Hz. Instead they take their 8000 samples per second > and up-sample by duplicating each sample 2 or 3 times to give us audio that > appears to be sampled at 22050 samples per second as requested, but it > still cannot faithfully render frequencies above 4000 Hz, so our piano > tuning app gives very strange results for the top few notes on the piano. > > Does anyone here work with audio input apps and can you confirm this > problem on any other devices? You can test it out by sideloading our app > from > > www.tunelab-world.com/atl.html > > It will run in free-trial mode well enough to test this out. To test for > the sampling rate problem, tap on the large "A4" and select the note "B7" > by tapping on the "7" first. Then on a different device or computer, > generate a tone at 3950 Hz. One such on-line source is > > onlinetonegenerator.com/ > > If this tone produces just one peak in the spectrum display at 3950 Hz, > then everything is fine. But if this produces two peaks - one at 3950 and > the other at 4050, then you have a device that is sampling at 8000 Hz and > then up-sampling to feed our app a fake 22050 samples per second. > > -Robert Scott > Hopkins, MN > > -- > You received this message because you are subscribed to the Google Groups > "Android Developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/android-developers. > To view this discussion on the web visit > https://groups.google.com/d/msgid/android-developers/5ab48a86-f5a9-4996-93e8-f7abb7855104%40googlegroups.com > <https://groups.google.com/d/msgid/android-developers/5ab48a86-f5a9-4996-93e8-f7abb7855104%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/android-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/android-developers/CAMUXMhtFz6LvOcBQBa%3Dgz_BYUxnm5oNakFNc1T9mfOfhFaAirw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
