improving stream quality

[miranpozar]

Hi!

My first post here. We need help please! Newbie question.

We're setting up a shoutcast stream here at the local radio station. We are not satisfied with the sound quality as the sound coming out is somehow "dull"... lower and higher frequencies are cut and overally it's not what one would expect from a 128kbps stereo stream, especially comparing it to other stations!

We believe it's got something to do with the encoder built in the Shoutcast DNAS (we use latest version). Is there a way to improve the quality of the encoding routine or perhaps exchange it with a different external encoder (LAME)?

Or are we missing something else?

You can listen the stream here to get an idea:
http://194.165.104.23:8012

Thanks for you help.
Radio Tartini Piran Slovenia team.

[bored_womble]

shoutcast doesnt affect the quality of the source, it just allows people to stream it, ie. one source and many listeners.

I suspect you'll find what ever you are encoding from , perhaps the LAME configuration your side is not perfect, or if from a soundcard poorer cabling etc.

BW

[DJ AmPs]

Yea make sure your sound card is of high quality and all your grounding is good if you're piping the sound from an external source. The 128k LAME config is not all that bad with the Shoutcast DSP. The "lacking" you describe seems to be related to something else.

[miranpozar]

The soundcard input signal is of a very high quality, so that's not the cause of bad sound. The card is Soundblaster Live! We also streamed high quality mp3 files directly from the winamp and it sounded equally bad.

Then I found this dsp_sc.ini file in the Winamp's Plugin folder. There is this line that says:
QualityMode=9
We edited it to Quality=1, but then the PC couldn't cope it (an old Celeron 366, 128MB)... Winamp just took 100% CPU usage and the sound was choppy. We then set it to Quality=6 and it now takes only 50% CPU.

We are not sure if we got an improvement.

So... what's this Quality setting for and how to adjust it properly?

Thanks.

[DJ AmPs]

That's likely the LAME quality config. at 128k the difference isn't really evident other than cpu usage. Have you tried streaming mp3's direct, using "Winamp" as the source instead of the soundcard mode? Just want to make sure you're not streaming the mp3's through the Soundblaster loop back.

However, that card is decent enough for streaming... I'm not sure why you have quality issues. But I do suggest a better broadcast PC, and using the KX drivers instead of the crappy Creative bundle -- http://come.to/sblive

[djSpinnerCee]

First off, I don't think the dsp_sc.ini is meant to be edited directly by you -- it contains the settings that you configure via the plugin -- if you edit it manually, you risk creating settings that are not compatible with the stream encoder.

One of the first things you should look at when diagnosing poor quality is the audio level -- overmodulating is unforgiving -- this applies to Soundcard Input as well as pre-recorded MP3s -- if they were mastered incorrectly, they will downsample poorly.

Another thing you must make sure of is that you are not feeding back the output into the input when you use the Soundcard Input.

When I use the Crossfade Output Plugin it lowers the quality of the whole stream somewhat [I get intermittent pops and clicks] -- this may not impact you, but output plugins like EQ and other processors can degrade quality [through various means, overmodulation being one] as well as increase CPU utilization dramatically.