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Topic: Some streaming questions (Read 2957 times) previous topic - next topic
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Some streaming questions

Hi all,

I'm involved in setting up a streaming internet radio station. We have decided to use Ogg Vorbis but would also like to support MP3. This causes a problem for us because most of our DJ's have a 128kbps upstream connection and we would like to broadcast 1 x 80kbps Vorbis stream, 1 x 80kbps MP3 stream, 1 x 24kbps Vorbis stream and 1 x 24kbps MP3 stream.

Obviously we can't do all that over 128kbps, so the plan was to broadcast just the 80kbps Vorbis stream to the server and then use streamTranscoder (from www.oddsock.org) to transcode to the other bitrates/formats.

Unfortunately, on FreeBSD 4.9 at least it doesn't seem to be able transcode from Vorbis, I just get a core dump when Vorbis is the source (although MP3 as a source works fine). Does anybody have experience with this? Are there any other utilities than can perform the same task?

We would also like to keep the levels equal on all of our programs, both live DJ shows and also on the Ogg Vorbis files that will be used for our playlist to fill gaps between shows. I've looked at Vorbisgain and it seems that it only adds tags to the files that a 'replaygain' compatible player will adjust the volume accordingly. Is there any way to actually adjust the volume of the file so that replaygain does not need to be supported or enabled?

Also - is it possible to somehow normalize the volume of a live stream?

TIA for any help,
-dave

Some streaming questions

Reply #1
Quote
Unfortunately, on FreeBSD 4.9 at least it doesn't seem to be able transcode from Vorbis, I just get a core dump when Vorbis is the source (although MP3 as a source works fine).


I think oddsock may be interested in knowing of this bug...


Quote
I've looked at Vorbisgain and it seems that it only adds tags to the files that a 'replaygain' compatible player will adjust the volume accordingly. Is there any way to actually adjust the volume of the file so that replaygain does not need to be supported or enabled?


You will have to reencode the files with fitting volume levels if you don´t want the client software to do "smart" things.

I don´t know if streamTranscoder can do this (reading and applying ReplayGain tags) for you. Would be a cool feature IMO - so why not asking oddsock for this in the process of reporting the bug you found?

Quote
Also - is it possible to somehow normalize the volume of a live stream?


AFAIK that´s difficult as it´s impossible to predict the volume level of future content. You could end up with "volume pumping" as the normalizer en- or decreases the volume-level dynamically.

Some streaming questions

Reply #2
Quote
Unfortunately, on FreeBSD 4.9 at least it doesn't seem to be able transcode from Vorbis, I just get a core dump when Vorbis is the source (although MP3 as a source works fine). Does anybody have experience with this? Are there any other utilities than can perform the same task?

I've also experienced problems with oddsock's streamTranscoder on
FreeBSD, I believe we were running 4.7 at the time.  The solution we
found was to run multiple source boxes which worked well for several
months.
We offered two MP3 streams (16k and 96k) and two Ogg Vorbis streams
(also 16k and 96k) with standard links for each plus a link to listen
with a Java-based Ogg Vorbis player (jOrbis IIRC).  When we dropped
our MP3 streams we did not find a signifigant drop in listenership
and saw an increased demand for the Java-based player. 

Since we ended our stream last fall I've seen alot more headway in
the area of Ogg Vorbis players on the market, too.  Vorbis.com shows
that Real has even jumped on the bandwagon.  Just a suggestion, but
you may want to consider how many of your listeners really need, or
even want, MP3 streams.  There may be a few who cannot run either a
modern media player or a Java-based player, but they've got to be an
extremely small minority at this point.