Sampling rate: Recording

Good morning....

In the last few days, I don't know if there has been an update, I noticed that the sampling frequency of the audio file when recording an audio

in AM or SAM mode reception is saved with a value of 20250 creating a recognition problem during the conversion to MP3 which instead accepts a value of 22050.

This problem had never appeared before.

Is this some change to the WIN11 operating system brought about by the latest updates or a change in the KIWI operating system?


Comments

  • edited January 18

    Hello, I just tried it on my computer (MAC OS Ventura 13.7.1) and on Ipad IOS (18.2.1) and KiwiSDR version 1.800 (Trémolat, Nouvelle aquitaine, France), I get the following files (see photo).

    The audio files are generated in WAV PCM format, without encoding (no MP3), in mono, in 16 bits and with a sampling frequency of 12000 Hz. This gives a bitrate of 187.50 kbps :

    (12000 x 16)/1000 x (1000/1024) = 187.500 (187.5 kbps)

    Best regard, Philippe

  • Your recordings will have a sample rate of 20250 Hz if your Kiwi is configured for 3 channel 20kHz bandwidth mode. 12000 Hz if the Kiwi is set to 4 or 8 channel mode. Downloaded recordings are in WAV format and you can resample to 22050 in audio editing software such as Audacity and then save as MP3.

  • sox will also resample wav files

  • jksjks
    edited February 5

    The sample rate of .wav audio files is completely arbitrary. And that's why audio files generated by the Kiwi are the same as the Kiwi audio sample rate. Currently 12 and 20.25 kHz.

    Any program that wants to play audio via the system output device needs to arrange for resampling to a standard "sound card" sample rate (e.g. 48, 44.1, 22.05 kHz). And this is exactly what happens in the Kiwi Javascript code running on the browser.

    mp3 files have their own specialized encoding that result in standardized bitrates. I don't know what your error message is from. But if some program is attempting to interpret a .wav file produced by the Kiwi as an .mp3 that's never going to work. It needs to be read as a .wav by some program and resaved as a .mp3 if that's what you want.

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