Loop clik in Android Mobile

Special Interest Groups Audio Processing
1

I have a sample that loops perfect in Audacity but I get a click in every loop point
when i use it in the app in the Android Mobile.
What can I do?

kire

2

You have not provided enough information, but my guess is: don’t expect to get a seamless loop from an MP3 format file. MP3 format is not capable of seamless looping - the closest that you can get to a seamless loop when using MP3 files is to ensure that the loop starts with silence and ends with silence.

3

But the android phone should support WAV files too, Mrs WC’s Samsung Galaxy does, so try using WAV

WC

4

Thanks to both of you
kire

5

This is the way I have made it:

  1. Two epty mono tracks (44100Hz and 32-bit float)
  2. Create 80Hz sinus in the first and 100 Hz in the second
  3. Adjust the ends so they are perfect for a loop
  4. Create a stereo track
  5. Change 32-bit float to 16-bit PCM
  6. Save it as OGG Vorbis (22,4 kB )

When I listen to it looping in audacity there is no click
The sound is a part in our mobile app - almost finished
When used there there is a click in every loop-point

If I save it from audacity as a WAV it is 1.0 MB
We are short memory space

All other audacity loop-sounds have worked OK - but with stereo channels all over.
The 80 and 100 Hz must be on right and left channel respectivly.

Is there anything I can try?

6

It seems that it is a playback issue rather than anything else as you say the loop plays fine in Audacity.
Since you only need frequencies up to 100 Hz, could you use WAV format with a much lower sample rate? With good resampling you could go down to less than 300 Hz sample rate and still produce a perfect 100 Hz sine wave.

(The absolute technical limit is double the highest frequency that you wish to produce, so for a 100 Hz sine wave the sampling frequency must be greater than 200 Hz. In practice due to imperfections in resampling you are unlikely to be able to go below about 240 Hz sampling rate, possibly much higher, but even with a sample rate of 8000 Hz the file size savings are considerable).

7

Thanks for your Info
kire

8

kire, something you might like to know is that for the next release of Audacity Steve has been doing a lot of work improving the Timeline Quick-Play functionality which will make creating seamless loops a lot slicker and easier.

WC

9

Thanks again
When is the release?

10

We’re hoping to move into new functionality freeze soon with a month then to mop up bugs - so the earliest we are looking at is the end of June.

WC