[App_rpt-users] Streaming questions

Bote Man bote_radio at botecomm.com
Fri Sep 23 15:42:32 EDT 2011


An Icecast server can offer multiple streams off of one ip:port pair via
a mechanism known as a "mount point". That trailing string after the
right-most slash is the name of the mount point. I think it defaults to
the word "mount" but I don't see how that is a stumbling block since
every Icecast stream employs that nomenclature.

 

It is up to the listener's computer as to how to open the stream based
on the extension .mp3 so that is out of your control.

 

Although in my case I don't use the extension and it works in most
cases, I think based on the server type header information.

 

As a test, try clicking each of these to see what it does on your
computer:

 

http://colostreaming.com:8000/botewild.m3u

 

http://colostreaming.com:8000/botewild.mp3

 

http://colostreaming.com:8000/botewild

 

The audio levels are also critical. Driving the encoder too hard could
result in tinny audio; conversely, driving the encoder with too weak
audio will result in muddy sound. If I listen carefully to my feeds I
can detect the tiniest bit of stair-stepping during audio peaks, but
overall I quite like the audio on there as I strive to set a good
example with it. FYI, my feeds use a Windows application called
RadioFeed which incorporates the lame encoder. It's a great free program
that's perfect for putting a scanner stream online.

 

As for Chipmunks, it sounds like you might be changing the sample rate
without actually resampling the audio. Does your Icecast server play a
recorded introductory announcement at the start of each stream session?

 

Bote

 

 

From: app_rpt-users-bounces at ohnosec.org
[mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Tony KT9AC
Sent: Friday, 23 September, 2011 11:58
To: app_rpt-users at ohnosec.org; Steve Passmore
Subject: Re: [App_rpt-users] Streaming questions

 


Thanks Steve, I'll play with these settings. I initially tried 3K as a
cutoff but still hear the "artifacts" noise that comes with Allison
announcing things (that's how I test quietly). It reminds me of how P25
sounds on the fringe, so its likely something in the conversion to MP3
from RAW or GSM.

 

I guess for streaming, we don't need a range like what a radio would
provide (say 300-3000hz), but perhaps something narrower.

 

To answer Bote as well, I'm using these standard settings for Lame, and
most changes from say 8K to 22.05K make it sound like Chipmunks got into
the system. I'm still learning the settings.

 

I still need to figure out how to get the stream to work at the base
URL, not requiring a filename. 

 

Tony

 


--- On Fri, 9/23/11, Steve Passmore <k6kya at hokeynet.net> wrote:


From: Steve Passmore <k6kya at hokeynet.net>
Subject: Re: [App_rpt-users] Streaming questions
To: app_rpt-users at ohnosec.org
Date: Friday, September 23, 2011, 12:03 AM

Got my Highs and Lows swapped...   oops

On 9/22/2011 22:00, Steve Passmore wrote: 

I don't believe wav is a stream-able protocol.  The metallic sound is
more an artifact of compression than the protocol used.   You might try
bumping up the bitrate and/or adding a lowpass filter to strip off the
highest  frequencies,  this is commonly done with stream encoders.  I've
added a highpass filter to remove PL.  I imagine you could do low pass
the same way.   Here's what I use.

outstreamcmd=/bin/sh,-c,/usr/bin/lame --preset cbr 24 --highpass 0.2 -r
-m m -s 8 --bitwidth 16 - -  | /usr/bin/ezstream -c /etc/ezstream.xml

Steve

 

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