[Icecast] Bandwidth Usage

Philipp Schafft lion at lion.leolix.org
Mon Oct 14 12:07:31 PDT 2013


reflum,

On Mon, 2013-10-14 at 19:07 +0100, Keith Roberts wrote:
> On Mon, 14 Oct 2013, Basil Mohamed Gohar wrote:
> 
> > To: icecast at xiph.org
> > From: Basil Mohamed Gohar <basilgohar at librevideo.org>
> > Subject: Re: [Icecast] Bandwidth Usage
> > 
> > On 10/14/2013 12:42 PM, Keith Roberts wrote:
> >> If there is no sound input on the client audio stream being
> >> sent to the icecast server does this mean there is no
> >> bandwidth being used - or does icecast use bandwidth even
> >> for times when there is no sound on the client input end?
> >>
> >> Kind Regards,
> >>
> >> Keith Roberts
> >
> > That all depends on the method of encoding being used on the
> > input/source side.  If you are using a VBR (variable bitrate) method,
> > such as the default/recommended encoding method for Ogg Vorbis, the
> > bitrate will be much less during these silent parts.
> >
> > Alternatively, if you're using a CBR (constant bitrate), the bandwidth
> > will be nearly constant regardless of level of sound input, even during
> > silent segments.
> >
> > Neither of these modes have anything to do with Icecast itself, but
> > rather, everything to do with your stream source.
> 
> OK thanks for that advice Mohamed. So it will be line input 
> audio sine wave into the soundcard, and then use the 
> default VBR to encode the stream to OggV and stream that up 
> to the icecast server?

As Mohamed already pointed out it all depdends on what is before your
encoder and is not strongly related to icecast.

If you are encoding from an anlog source (without some post processing
on your system) your stream will likely drop in used *bitrate* but not
to zero as the codec will encode the noise from that input.

This is true and should work fine with icecast (no strange timeouts and
stuff) with Ogg Vorbis which I strongly recommand for most setups.
In case of Vorbis I also recommend not to set bitrate or encoder mode,
just set the quality value and let the encoder do a good job. (Changing
too many parameters will often end in less quality per bitrate).

Have a nice day :)

-- 
Philipp.
 (Rah of PH2)
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