I'm not sure if this is possible at all or if its not possible with the information that I currently have. If it's not possible please let me know. I'm not the best in math so searched on the internet but didn't find a suitable answer.
I'm building a USB device with receives information from Windows on the current volume setting and I would like to calculate that into a percentage. The issue that I'm facing is that the information received is not linear as it is notated in decibel.
I have the following information (raw and decibel):
- lowest possible value: -1536 -> 0db (ie 0%)
- highest possible value: 9216 -> 36db (ie 100%)
- The received can never exceed these 2 values
since the lowest possible value is negative I increased all values (lowest, highest and incoming) with 1536 so that I wont have to deal with negatives. My latest attempt is close but not good. 98% in windows would calculate into 91% for me:
$(((receivedDB - dB_L) * 100) / (dB_M - dB_L))$
I'm not sure if this can help, but here are some values that Windows sends (from 100% to 90% (windows volume scale), windows jumps by 2%) these are corrected (increased by 1536):
- 10752
- 9814
- 9814
- 6891
- 7884
To calculate the DB this formula is used $value * (1 / 256)$
- I know that the values received can used to calculate the dB with the formula shown as mentioned by the USB foundation datasheets. By looking at it, its not linear
- The values are correct, but there is no nice shift in between values. I didnt want to post all the values as it will be a mess. Here is the full list: https://pastebin.com/SPhE3vvf. The first 3 0's can be seen as 0%, but the value 47 is 4% if that makes sense
– wes Jan 27 '22 at 13:37