[Icecast] icecast sound compressor

Balint Jacint bjacint at kvark.hu
Sun Jun 5 19:59:11 UTC 2005


Thanks for all of you for your replies!
I took a look at every software you mentioned, and ecasound looks the 
best for me with LADSPA and TAP-plugins.
Just for the sake of Google search and maybe some us you may be 
interested, this is the command I'll use for compressing the online ogg 
vorbis broadcast:

ecasound -f 16,1,44100 -i /dev/dsp -eli:2152,20,1000,20,20,0,0,0,0,6 -o 
stdout | ices2 ices.xml

the 2152 LADSPA plugin is TAP Dynamics (M), with compression of 3:1 at 
threshold -35dB (15+20, as the number 6 represents 3:1 compression at 
-15dB) and after-compression-gain +20dB, 20ms attack and 1000ms release 
times. This is radical, but I want to compress speech where the only 
criteria is for the speech to be understandable. (I may change it later.)
(If you install the LADSPA-plugin for xmms and the TAP-plugins, xmms 
tells you the exact order the numbers are used and their meaning.)

In the ices.xml the interesting lines are:

            <param name="rate">44100</param>
            <param name="channels">1</param>



Geoff Shang wrote:

> Hi,
> It's going to depend a bit on what format you're going to use.
> If you plan to stream in ogg vorbis, you can use Ices 2.x and accept 
> PCM via standard input.  This means you could run a sox effect or 
> ecasound to get and compress the sound from the soundcard before 
> sending it on to ices. Ecasound can make use of LADSPA plugins which 
> opens you to a range of compressors, such as the SWH compressor 
> plugins which I'm told are pretty good.
> If you want to do MP3 then I don't have any good ideas so far.  
> Darkice doesn't allow either receiving from standard input or 
> inserting processing (i.e. starting a subprocess which it sends audio 
> to and receives audio back from), either of which would be useful 
> functions, and I don't know if Ices 0.x can accept PCM via stdin either.
> I'd be interested to know how you go.  I've not looked at the sox 
> compression effects lately so they might do the job, don't know.
> Geoff.

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