Question: How is the average codec bitrate calculated for audio media, considering the use of silence frames (SID-frames) in the audio codec?
Option 1: Total audio bits received for all frames (including SID-frames) divided by the total measurement resolution period.
Option 2: Number of audio bits received for 'active' frames only, divided by the total time covered by these 'active' frames.
Option 3: Total media bits played out during the measurement resolution period, divided by the length of the playout period (applying to both audio and non-audio media equally).
Option 4: Average of peak bitrate and lowest bitrate used during the measurement resolution period.
Explanation: For audio media, the average codec bitrate calculation specifically excludes silence frames (SID-frames) and their corresponding DTX time periods. This means only 'active' frames containing audio are considered. The correct calculation involves dividing the number of audio bits from these 'active' frames by the total time covered by just these frames, which is calculated as the number of 'active' frames multiplied by the length of each audio frame. This approach ensures that periods of silence do not artificially lower the average bitrate, providing a more accurate representation of the codec's bitrate when actively transmitting audio content.