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Fax over G.711

asked 2018-08-27 18:21:21 +0000

Guillaume gravatar image

Is it something that could be possible that you support Fax over G.711 stream decoding and not just Fax over T.38?

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answered 2018-08-27 19:05:04 +0000

Jaap gravatar image

That would require Wireshark to do a lot of audio processing: getting the samples out of the stream, converting these to symbols, synchronise on the stream, get the HDLC frames, strip these off and then go to FAX decoding. Possible, but not simple.

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There is a software called spandsp which can process an audio recording of a fax session offline the way you want. But you can export the G.711 from the RTP stream into an audio file and then use spandsp's fax_decode to show you the T.30 events and create the image file. On Windows, I'm running it under cygwin.

sindy gravatar imagesindy ( 2018-08-27 20:24:09 +0000 )edit

Can you explain me how can I run this program in cygwin. I am a total noob in programing.

Guillaume gravatar imageGuillaume ( 2018-08-28 13:32:14 +0000 )edit

Unfortunately I cannot because a colleague who has already left the company has compiled it for me years ago, and since then the cygwin has evolved so is quite likely that the same binary will not run on a new installation of cygwin. So I can send you the binary if you give me your e-mail (you can post it here in some robot-unreadable form and remove the comment once you get an e-mail from me), but whether it will run in your newly installed environment is not guaranteed.

sindy gravatar imagesindy ( 2018-08-28 13:54:02 +0000 )edit

We already have the spandsp as optional library on board, for the handling of ADPCM streams. But again, it's an output pipeline, working on tap data, and not part of the dissection engine.

Jaap gravatar imageJaap ( 2018-08-28 16:45:33 +0000 )edit

@Guillaume, I have sent you an e-mail with a link and erased your comment with the e-mail address, have you received the e-mail or not?

sindy gravatar imagesindy ( 2018-08-29 08:35:33 +0000 )edit

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Asked: 2018-08-27 18:21:21 +0000

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Last updated: Aug 27 '18