Hello Cyprien,
The frameWidth is the sweep size divided by an even integer if the sweepSize is >= 1024. This means, the frameWidth will always be between 512 and 1023. Example, If the sweepSize is 1026 then the frameWidth will be 513, and each column in the frame will be the contribution of two bins of the sweep. We always use an even integer divisor so you can consistently determine which sweep bins fall into the frame columns.
The frame returned is the accumulation and scaling of the last 20 frames. It is implemented as a 20 frame FIFO. If you specify the default 30FPS, then each frame is the accumulation of the last 2/3 second.
If you have any further questions, let me know.
Regards,
A.J.
