[@njwdt] I got the same error messages. I used a 20 second wave file with a standard sample rate 44100hz to produce 3 different mp3 files of 3 different bit rates ranging from 96-160 bps. The files sizes were only 300-500 KB. In all 3 files I got the following messages
Mode1: Error: Audio file is too large!
Mode2: Error: UNSUPPORTED_SAMPLE_RATE， please contact the support team or try other modes.
There was nothing on their web site giving guidance about using modes 1 & 2. Incidentally, the web site doesn’t provide a secure http connection!!!