{"id":76,"date":"2014-02-16T19:24:58","date_gmt":"2014-02-17T00:24:58","guid":{"rendered":"http:\/\/dogphilosophy.net\/?p=76"},"modified":"2025-01-23T18:14:24","modified_gmt":"2025-01-23T23:14:24","slug":"subversive-radio-hostraspberry-pi-fm-streaming","status":"publish","type":"post","link":"https:\/\/dogphilosophy.net\/?p=76","title":{"rendered":"“Subversive Radio Host”\/Raspberry Pi FM Streaming"},"content":{"rendered":"

I’m working on earning my “Subversive Radio Host” merit badge with my RaspberryPi. Once I’ve got the whole system worked out I’ll likely be doing a Hacker Public Radio episode about it<\/a>. In the meantime, though, for testing purposes I have a feed from the local NOAA Weather Radio which I am feeding as 10kbps opus audio to an instance of icecast2.<\/p>\n

I figured I’d post this since there’s a piece of information I found today regarding having a continuous stream, and someone else may find it useful.<\/p>\n

I was finding that my stream to the icecast server, using the command line suggested by the opusenc man page<\/a>, was spontaneously dying at almost precisely 6 hours, 12 minutes, and 50 seconds. For reference, here’s what the man page says (or at least has for quite some time now and did when I last checked it today) as a suggestion for live-streaming recorded audio in realtime:
\n
\narecord -c 2 -r 48000 -twav - | opusenc --bitrate 96 - - | oggfwd icecast.somewhere.org 8000 password \/stream.opus
\n<\/code>
\nI was using the same string of commands, with minor changes (only one channel, –bitrate 12 [or 10], different address and credentials for oggfwd).<\/p>\n

To cut the drama short, the problem turns out to be arecord. I still am not sure whether arecord was hitting a “maximum number of bytes” or “maximum run time” problem, but either way, it turns out you can just use sox<\/a> (symlinked as “rec”) in its place, which is nice because I had been thinking about playing with having sox apply some filtering to remove noise, etc.<\/p>\n

Here’s a suggested replacement command line for this purpose:
\nrec -c 1 -t wav - | opusenc --bitrate 10 - - | oggfwd icecast.somewhere.org 8000 password \/stream.opus<\/code>
\n(with the parameters adjusted to your own needs, of course).<\/p>\n

It’s been going for over 7 hours now, so I’m assuming my problem is resolved. In the long run it won’t matter so much – my intended use-case in the end involves playing pre-recorded files (and would work perfectly with ices2<\/a>‘s features if ices2 supported opus…), but for times when I may want to live-stream something, this may come in handy. With opus at 10-12kbps being still decent quality for voice, one ought to be able to feasibly live-stream audio even over a really slow pre-“3G” cellphone data link or dial-up modem in realtime.<\/p>\n

Oh, speaking of “Subversive Radio Host” – using the clever pifm<\/a> software turns the Raspberry Pi into a remarkably powerful transmitter. I think I’ve got my antenna trimmed down enough to make it a legal unlicensed transmitter (my original test was with a 20″ or so piece of alligator-clip wire that happened to be handy, and got the signal out to about three blocks away. Definitely too much power for legal unlicensed use.) I suspect with an ideal-length wire as an antenna you could cover a whole town, if you placed it well, and if you didn’t mind getting the FCC (or whoever your local regulatory agency is) very annoyed with you.<\/p>\n","protected":false},"excerpt":{"rendered":"

I’m working on earning my “Subversive Radio Host” merit badge with my RaspberryPi. Once I’ve got the whole system worked out I’ll likely be doing a Hacker Public Radio episode about it. In the meantime, though, for testing purposes I have a feed from the local NOAA Weather Radio which I am feeding as 10kbps […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/posts\/76"}],"collection":[{"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=76"}],"version-history":[{"count":3,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/posts\/76\/revisions"}],"predecessor-version":[{"id":159,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=\/wp\/v2\/posts\/76\/revisions\/159"}],"wp:attachment":[{"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=76"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=76"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dogphilosophy.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=76"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}