[Freeswitch-users] Better results from mod_vmd

Eric des Courtis eric.des.courtis at gmail.com
Mon Aug 17 14:15:57 PDT 2009


Matt,

Okay the good news is vmd should be able to handle these cases. The
bad news is for whatever reason they are not getting detected at the
moment.

vmd-not-panasonic-home-ans.wav is a sine at ~1400Hz you can change
MAX_FREQ to 1450 and play with MIN_AMPL if that still doesn't help.

The following seem to use the same beep:

vmd-not-tmobile.wav is a sine at ~750Hz but has a bit of noise
vmd-not-sprint.wav is a sine at ~750Hz but has a bit of noise
vmd-not-sprint.wav is a sine at ~750Hz but has a bit of noise

You can try to play with these values:

POINTS 32
VALID 22
MAX_CHIRP 22

If that doesn't work let me know I will try to improve the algorithm
to detect the providers.

Cheers!

Eric des Courtis



On Mon, Aug 17, 2009 at 1:52 PM, Matthew Fong<mattdfong at gmail.com> wrote:
> Hi Eric,
> Thanks for the response. I had tried emailing you @brenbria.com and the
> email had bounced, thanks for responding to my mail.
> If you'd be interested I .zipped up my sample voicemail beeps
> at http://bandcon.hellohunter.com/vmd_wav.zip
> I'm relatively new to telephony, but can you point me in the right direction
> for figuring out if the beeps are sinewaves. About as far as I've come with
> audio is being able to open the .wav files in audacity. Any website
>  recommendations I can read? Thanks so much.
> --matt
>
> On Mon, Aug 17, 2009 at 10:29 AM, Eric des Courtis
> <eric.des.courtis at gmail.com> wrote:
>>
>> Matt,
>>
>> You must first capture the audio beeps and verify that they are sine
>> waves. If not, simply tweaking the algorithm will not give you better
>> results.
>>
>> It might be possible to use FFT and I would be happy to help you
>> implement such a solution but keep in mind FFT is very very demanding
>> on the hardware. Ideally what you want to find out is what functions
>> was use to generate the beep in the first place so that it can be
>> detected. Is it two sines waves like in DTMF? Or something more
>> complex?
>>
>> Anyway my email is eric.des.courtis at benbria.ca.
>>
>> Cheers.
>>
>> Eric des Courtis
>>
>> On Mon, Aug 17, 2009 at 12:26 AM, Matthew Fong<mattdfong at gmail.com> wrote:
>> > I tried emailed Eric, seeking advice on this, but his email (the one in
>> > the
>> > source code) is bouncing email (invalid user), so thought I would ask
>> > here
>> > instead. If anyone has eric's new email address, I'd be interesting in
>> > it.
>> >
>> > I did some tests with mod_vmd this afternoon, but I'm only finding about
>> > 33%
>> > of the voice mail beeps and did have 1 false-positive in my test of
>> > 7 voice
>> > mail machines. I've recorded the audio of the session in .wav files that
>> > were both successful and not, as a comparison. I can upload the .wav
>> > files
>> > if they would be useful.
>> > mod_vmd works great for voicemails of Skype Users, and kall8.com, but
>> > has
>> > issues dealing with mobile phone carriers.
>> > sprint - not successful
>> > tmobile - not successful
>> > verizon - not successful
>> > panasonic home answering machine system - not successful
>> > kall8 - SUCCESS
>> > skype - SUCCESS
>> > I'm wondering if you can recommend a simple fix, like changing some of
>> > the
>> > constants like MAX_FREQ, or MIN_TIME at the top of the mod_vmd.c source
>> > file, or if better success requires more complex analysis.  Do you have
>> > any
>> > recommendations on how this might be done? Listening to the .wav's
>> > its apparent the beeps are not as loud for the mobile phone carriers as
>> > they
>> > are with skype and kall8. Any guidance would be greatly appreciated.
>> > --matt
>> > hello hunter
>> > http://www.hellohunter.com
>> > voice broadcasting & hosted dialer
>> > _______________________________________________
>> > FreeSWITCH-users mailing list
>> > FreeSWITCH-users at lists.freeswitch.org
>> > http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> > UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> > http://www.freeswitch.org
>> >
>> >
>
>




More information about the FreeSWITCH-users mailing list