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WLUG Meeting Jan. 14th @7pm WPI Mid century Room (rm 331)
by Tim Keller Jan. 12, 2016

Jan. 12, 2016

Hey Gang, Sorry for the late email, it's been hectic at my end of things. Here are the facts! Date & Time: January 17th, 2016 @ 7PM Location: WPI Student Center Mid Century Room (rm 331) Topic: None* *There's currently no topic ... I contemplated talking, but never got stuff together. Due to a scheduling conflict, I'll be unable to attend... so if someone else would like to step up for snacks and refreshments that would be quite helpful. I know people had a busy holidays, so my plan *was* for this to just be a general meeting anyway. We can get our heads around what we'd like for speakers for the coming year. My hope is to get my buddy Nick to do a deep dive talk about encryption in February. I know Greg had mentioned speaking about setting up a radio station. Please submit any suggestions! Thanks, Tim. -- I am leery of the allegiances of any politician who refers to their constituents as "consumers".

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Re: [Wlug] Audio processing question
by John Stoffel Dec. 28, 2015

Dec. 28, 2015

Andy> I thought so, too, but I cannot find a menu option or a command Andy> line option to do it. Am I blind? :-) I'm running dream Andy> version 2.1.1-svn808. In the SNAPSHOTS directory on sf.net, I Andy> see dream-935 from Nov 2014 which is more recent but when I Andy> compile it, it segfaults upon execution. Hmm... maybe they have some newer code elsewhere? I'm not sure how I could help at this point, beyond trying to compile the code with debug info and then pulling it into gdb to get a backtrace. I suspect you'll have to ask on the mailing list for dream, since what I see on the web page implies that network stuff works... but not sure. I would think that dream could just pull the data directly from the radio itself, to cut out the middle man here.

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Re: [Wlug] Audio processing question
by Andy Stewart Dec. 27, 2015

Dec. 27, 2015

On 12/27/2015 05:38 PM, John Stoffel wrote: >>>>>> "Andy" == Andy Stewart <andystewart(a)comcast.net> writes: > > Andy> Closer: > > Andy> nc -l -u 65535 | sox -r 48k -b 16 -c 1 -L -e signed -t raw - \ > Andy> -t wav radio.wav > > Andy> ...but....the mondiale decoder doesn't like reading radio.wav: > > Andy> sox WARN wav: Length in output .wav header will be wrong since can't > Andy> seek to fix it.. > > Andy> Still plugging away...... > > So what mondiale decoder are you using, dream from sourceforge? I've > just poked at the dream web page and it looks like it's got network > input support, so I'm wondering if you cant' get the data from gprx -> > nc -> dream -> speakers > > to do the decoding. Hi John, I thought so, too, but I cannot find a menu option or a command line option to do it. Am I blind? :-) I'm running dream version 2.1.1-svn808. In the SNAPSHOTS directory on sf.net, I see dream-935 from Nov 2014 which is more recent but when I compile it, it segfaults upon execution. Andy -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF)

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Re: [Wlug] Audio processing question
by John Stoffel Dec. 27, 2015

Dec. 27, 2015

>>>>> "Andy" == Andy Stewart <andystewart(a)comcast.net> writes: Andy> Closer: Andy> nc -l -u 65535 | sox -r 48k -b 16 -c 1 -L -e signed -t raw - \ Andy> -t wav radio.wav Andy> ...but....the mondiale decoder doesn't like reading radio.wav: Andy> sox WARN wav: Length in output .wav header will be wrong since can't Andy> seek to fix it.. Andy> Still plugging away...... So what mondiale decoder are you using, dream from sourceforge? I've just poked at the dream web page and it looks like it's got network input support, so I'm wondering if you cant' get the data from gprx -> nc -> dream -> speakers to do the decoding. John

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Re: [Wlug] Audio processing question
by Andy Stewart Dec. 27, 2015

Dec. 27, 2015

On 12/27/2015 01:01 PM, Andy Stewart wrote: > Here's a command that works, to give you a feel for the data formats > involved: > > gqrx outputs RAW audio data to UDP port 65535 > netcat -l -u 65535 | aplay -r 48k -f S16_LE -t raw -c 1 > correct audio is heard > > Now, I want to get that into a WAV file or perhaps a fifo from which the > mondiale decoder could get its input. > > netcat -l -u 65535 | sox ??? > > The man page for sox is not for the faint of heart, and I'm not an audio > expert. > > Any ideas? > > Thanks! > > Andy > Closer: nc -l -u 65535 | sox -r 48k -b 16 -c 1 -L -e signed -t raw - \ -t wav radio.wav ...but....the mondiale decoder doesn't like reading radio.wav: sox WARN wav: Length in output .wav header will be wrong since can't seek to fix it.. Still plugging away...... Andy -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF)

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Re: [Wlug] Audio processing question
by Andy Stewart Dec. 27, 2015

Dec. 27, 2015

On 12/26/2015 07:32 PM, Andy Stewart wrote: > On 12/26/2015 06:17 PM, Frank Sweetser wrote: >> I'd bet that you could use netcat do listen ona socket and dump the results directly to a file. OK, I'm getting closer. It turns out that the UDP audio stream is RAW. The "mondiale decoder" wants to see WAV data. I think I need the correct incantation of the sox command. Here's a command that works, to give you a feel for the data formats involved: gqrx outputs RAW audio data to UDP port 65535 netcat -l -u 65535 | aplay -r 48k -f S16_LE -t raw -c 1 correct audio is heard Now, I want to get that into a WAV file or perhaps a fifo from which the mondiale decoder could get its input. netcat -l -u 65535 | sox ??? The man page for sox is not for the faint of heart, and I'm not an audio expert. Any ideas? Thanks! Andy -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF)

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Re: [Wlug] Audio processing question
by John Stoffel Dec. 26, 2015

Dec. 26, 2015

>>>>> "Andy" == Andy Stewart <andystewart(a)comcast.net> writes: Andy> What I want to do is listen to the DRM broadcast in real time. I was Andy> unsuccessful in getting Dream to read the WAV file while it was being Andy> written. >> Andy> Does anybody have any suggestions as to how this could be done? >> >> Have you tried setting up a FIFO that each program opens and treats as >> a WAV file? That might be the way to have them talk to each other. >> >>> mkfifo /var/tmp/radio >>> gqrx --output /var/tmp/radio >>> mondiale --input /var/tmp/radio >> >> though I havent' a clue what the two programs do at the commmand >> level. Andy> That is an interesting idea but gqrx doesn't let the user pick a Andy> file name for saving the WAV audio. It creates a file name by Andy> an internal algorithm. All I can do is pick the directory in Andy> which that file is saved. Andy> Is there a way that I can tie a file to a UDP port? gqrx will Andy> output an audio stream on a UDP port. If I can make that look Andy> like a file, perhaps "mondiale" will consume it. Hmm... maybe using 'nc' (netcat) to listen to that UDP port and then feed the info into either the FIFO or directly into the other tool? Are they open source? It might just be time to hack some source to do what you want... I also think the JACK audio thing might work, where you setup some virtual Mics and Feeds to connect the two programs together. John

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Re: [Wlug] Audio processing question
by Andy Stewart Dec. 26, 2015

Dec. 26, 2015

On 12/26/2015 06:17 PM, Frank Sweetser wrote: > I'd bet that you could use netcat do listen ona socket and dump the results directly to a file. > I can't try it again until the DRM station broadcasts when I can receive it. I knew I should have recorded the I and Q when I was listening to it! I think this will work (not literally but you get the idea): mkfifo /tmp/radio gqrx > udp:65535 netcat -l -u 65535 > /tmp/radio "mondiale decoder" < /tmp/radio I'll let you know if this works. I'm also open to other suggestions, and still looking at JACK. Andy -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF)

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Re: [Wlug] Audio processing question
by Frank Sweetser Dec. 26, 2015

Dec. 26, 2015

I'd bet that you could use netcat do listen ona socket and dump the results directly to a file. On December 26, 2015 6:15:31 PM EST, Andy Stewart <andystewart(a)comcast.net> wrote: > > >Is there a way that I can tie a file to a UDP port? gqrx will output >an >audio stream on a UDP port. If I can make that look like a file, >perhaps "mondiale" will consume it. > >Andy -- Sent from my Android device with K-9 Mail. Please excuse my brevity.

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Re: [Wlug] Audio processing question
by Andy Stewart Dec. 26, 2015

Dec. 26, 2015

On 12/26/2015 04:13 PM, Steve Revilak wrote: >> Hi gang, >> >> I think I need something like the Virtual audio cable, but I'd like to >> know if there are other possibilities. >> >> I have two audio programs that I want to talk to each other: gqrx and >> Dream. > [..] > > > Jack might be worth a try. http://www.jackaudio.org/ > > Steve Thanks, Steve, I'm looking at it but I'm not finding usage examples that tie together two programs. I'll keep looking. Andy -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF)

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