I am using new (8841) and old (509G) IP phone products for performance testing. On the phone web page, I can observe the status information during the call, one of the information is called "Decode Latency", and the official website defines this as "Number of milliseconds for decoder latency.". I am still a little vague about this value. From my observation, when the 8841 is as the receiving end, the value of this information is the same as the "Packet Size" value set by the calling end phone, so I try to interpret "Decode Latency" to "Detecting the frame length to be decoded in the received RTP packet"; But when 509G is the receiver, this value changes at any time, which overturns our original assumption. Does anyone can help to clarify the meaning of this value in more detail?
In addition, I am trying to find an alternative to 509G, and 8841 is the model recommended by the official website. However, I attach great importance to the codec processing performance of the phone, espicially focus on the performance of the phone playing the decoder role, so l conducted a test. Through my experiment, I found that in the same test scenario and a simple LAN environment, the delay of 8841 was worse than 509G. Our test scenario was 509G→switch→(509G or 8841), and tried to get the one-way delay. We used an oscilloscope, put the probes at the sender's microphone and receiver's speaker, and got the delta time between two observed channels, the result of avg delay of 509G was 72.1ms, and 8841 as the receiver was 108ms. Are there any find tune suggestions to improve the performance of 8841, or other models that can be recommended for?
Ps. The test results came out under the configuration of 711u codec and 30ms packet size.
