While creating a new KRec-file this dialog is displayed and lets you choose some settings for the quality of the recordings. All of these settings have an impact on the size.
The sampling rate is the rate which tells audiosystem how many samples to take during a second and is measure in Hertz (Hz) respectivly Kilohertz (kHz). The higher this rate the higher is the maximum recorded frequency. Since at least two samples are needed to rebuild a “sinus”-wave the maximum recording frequency is half of the sampling rate. The human ear is capable of hearing tones up to something between 10kHz and 20kHz depending on the age, little children are possibly nearer to 20kHz while normal adults have their maximum around 15kHz and elder people go down to 10kHz. But even without actually hearing the higher frequencies they still have an impact on what is heared and felt (corresponding keyword: psycho acoustics).
The number of channels can be freely choosen depending on the task of the recording. If you are using a mono-microphone without applying a stereo effect you can safely choose “Mono” without the loss of data.
The last part are the number of bits used for one sample, possible values are 8 and 16 bits. The more bits the more steps are available for the range from minimum and maximum signal. 8 bits are one byte so this can also be referred to as one byte or two byte samples.
The space needed for the recording can be calculated in a very simple way: Its the sampling rate multiplied by the number of channels multiplied by the number of bytes per sample multiplied by the number of seconds wanted to record.
Example 4.1. Calculating the size of one minute CD quality
For one minute (60 seconds) audio in CD quality (44100Hz, 16bits, stereo) the space needed is: 44100 * 2 * 2 * 60 = 1058400 Bytes = 10335.938 Kilobytes. That is around 10 MByte of data per minute.
Always use the best needed quality! Reducing the quality later on is always possible, but enhancing the quality is not possible since then more data as available is needed.
The last item above the button is a checkbox for using the entered values as defaults for every new file without showing this dialog again.
As the same dialog is also available in the configuration to choose the standard settings, the "Use defaults..." checkbox is also accessible from there to get the dialog for every file back.
Would you like to make a comment or contribute an update to this page?
Send feedback to the KDE Docs Team