Question: In the EVS (Enhanced Voice Services) codec, under what conditions is the counter for bandwidth switching from WB (WideBand) to SWB (Super WideBand) incremented in the Bandwidth Switching Detector?
Option 1: When the output bandwidth of the current frame is SWB, the total bit rate of the current frame exceeds 9.6kbps, and the previous frame's bandwidth was WB with a total bit rate not exceeding 9.6kbps.
Option 2: If the previous frame's bandwidth was SWB and the current frame's bandwidth switches to WB regardless of bit rates.
Option 3: When both the current and previous frames have a total bit rate exceeding 9.6kbps, irrespective of their bandwidths.
Option 4: If the counter for switching from SWB to WB has reached its maximum value.
Explanation: This is correct because, according to the described algorithm for the Bandwidth Switching Detector in the EVS codec, the specific condition for incrementing the counter for WB to SWB switching involves a transition from a WideBand (WB) frame with a bit rate of up to 9.6kbps to a Super WideBand (SWB) frame with a bit rate exceeding 9.6kbps. This precise scenario matches Option 1, highlighting the detector's focus on bit rate thresholds as part of its decision-making process for identifying bandwidth switching events.