I am working on a project that requires me to detect FAX answer tone (CED) (2100Hz duration 2.6 to 4 seconds).
I created a tone using an online tone generator and fed raw PCM data to 'DetectTone' function multiple times, but it did not detect a tone. I tried initing USC_TD_Fxns with 'USC_ANSs_Fxns' and 'USC_ANSam_Fxns'.
Since this did not work, I did a loopback of the data generated by IPP 'GenerateTone' function the same way as above. I inited the tone generator with (USC_ANSam_Fxns) and generated USC_ANSam tone, with duration 10 and volume 1.
After feeding it to 'DetectTone' 36 times (160 bytes (10ms) of RAW PCM data) I was finally able to detect a FAX tone (USC_ANS). Frequency analysis in Audition shows this signal with 3800Hz peak.
I also tried FAXLab but IPP did not detect (CED) from this as well.
I am unable to understand why other tones at 2100Hz are not detected as valid CED. Please shed some light on this (How to create a CED tone so that IPP detects it, Limitations of IPP if any). If there is a detailed documentation (Not API docs) on what FAX tones are supported by IPP please point me to that as well.