Garbled playback in music stream

[Chassie Rowley]

I have recently set up a music stream (yeah, SL needed yet another), which by all accounts, sounds fine.

There are times when the music sounds garbled. The digital playback timer appears ok, as if the music is playing at the appropiate speed. I have checked all settings and they seem ok as well.

Any idea to what might be causing this garbled playback (buffing?) and any possible way to remedy it?

 

Shoutcast.

128 bitrate, 44100 mhz

 

Thanks Karen.

For what it's worth, my ping is 48ms, dl is 9.43 Mbps and ul is 2.93 Mbps, according to Speedtest.

I attempted reducing my Shoutcast bitrate output to as low as 56; 44100, with SOME favorable results, but in time, the garble returned. I tried playing a studio CD through Shoutcast to make sure I wasn't doing anything on my editing end (I use Audacity). Garble came again.

Any help from those who have had the same problem and solved it, will be appreciated.

 

Both answers are good. Thanks Karen

 

[KarenMichelle Lane]

Charlie,

Garbled music has a lot of potential causes so check into these things one at a time.

From the Broadcasting End:

1) The bandwidth from your ISP allocated for uploads to the Internet, is insufficient to maintain the stream-to-relay service connection.

A 128.kbps upload stream is not a big load for most ISP supplied modems to manage however, the ones you are "gifted" are all prioritized for download traffic, not upload traffic. Due to the idiosyncrasies of the TCPIP protocol, you require a steady 0.3 mbps to upload that stream. [ 2.5 times the actual speed for IP overhead wrappers and pacing ] But this only applies if you are also not uploading other information at the same time such as SL avatar positioning and orientation commands, scripted object state changes, you get the idea.

Relay Servers will backfill the stream dropouts with music already in the buffer for minor drops. This will sound like garbled music to the listener of your stream, including you if you are monitoring your stream using SL and it's FMOD player.

So if you have what is commonly called "High Speed DSL" then check your actual Internet speed using www.speedtest.net and pay attention to the actual upload speed.  If you wish to DJ or become a stream provider and want to use the internet at the same time for web browsing & SecondLife then make sure you have purchased and are receiving an upload speed of 0.6 mbps or better.

2) Your PC is being overtaxed.

A dual core i3 [4 logical processors] or older single core [2 logical processors] PC can be used to stream music to a relay service as well as listen to it from the relay service. The i3 is preferable because there are other processor threads available for managing additional PC activities, like the SL viewer, the SLPlugin.exe & a web browser. This is the key to multitasking. If your music streaming broadcasting software has the ability to prioritize it's own executable, then make sure it is running at the above average setting. This will tell the task scheduler to give a higher number of CPU cycles to that program thus keeping the stream output cleaner.

From the Receiving End:

SL uses the FMOD media library to playback sounds & music. SL controls it's performance via the SLPlugin.exe modules.

I'm assuming that until now you have never experienced music dropouts Now that you are not only generating music using a media player, you rare broadcasting it to a relay service for others to listen to. So you are tasking both your PC and your Internet Service with extra traffic.

so look at:

1) Your Internet Service Speed - Don't pay attention to what it says you are purchasing, use www.speedtest.net to verify what you are actually getting. Al ISPs say "Up to" in their package pricing & performance language.

2) Your PC CPU usage - a PC running at close to 100% on all processors will have issues with SL & with the music stream playback.

3) Your SL Bandwidth setting - The default value of 500 is fine in most cases. If you have really slow internet then set this to less than 500 a 100 at a time and retest.

I'll post moire as I remember other issues that may affect you.

 

 

 

 

[KarenMichelle Lane]

If you have 2.93 Mbps up and if your ISP is not using old school bursting protocols then the issue is with your PC - Use the Resource Monitor in Task Manager / Performance to identify that is causing your CPU or Internet activity to peek at 100% CPU or at the max of your NIC card.

When using a PC as a Music Streaming SOurce [Radio Station] you want all internal tasks to NOT run as scheduled because they can cause temporary stream interruptions...

Also check your Scheduled Task list for weird tasks that execute more than once an hour.

Keep you MP3 encodied stream at 128 kbps at a minimum or the sound will become muddy to your listener.