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Streaming in MP3

C

ChiefOperator

We currently stream our station using WMA and the our streams follows our on-air signal by about :20 - :30sec.

I'm curious about streaming in MP3. Could someone tell me the latency for this format?

Many of our listeners take their IPhones to our HS football broadcasts and wish to listen in real time.

Thanks!
 
I think there's going to be latency in the network and the encoder both but mainly in the network and buffering needed to make the stream not glitch all the time, etc. If you aren't running the game they are trying to listen to over-the-air you might try a "part 15" fm transmitter on a good unused frequency at the game. Sometimes low-tech is a better option if you can get them to bring radios (which may be the next issue, eh?)

Good luck!
 
The more folks you have on your distribution server, the longer the delay is going to be, assuming that buffering and any other latency issues are equal. Depending on serve load, you could see as much as 2 minutes of delay just from serving out the audio. The more folks, the more delay. It happens with WMA and mp3.
 
Thanks. They bring radios to the local games but are using IPhones on "away games."

Yes, I was afraid that I'd see the same delay issues at MP3 as well...
 
The delay has nearly nothing to do with the codec. The delay is due to the fact the players use TCP/IP and have large enough buffers they can ride through major network problems and the packets can still get re-sent before the player catches up.

Products designed to be used for remotes and STLs and whatnot use RTP/UDP. This allows the delay to be much shorter, with the downside that lost packets cannot be re-sent - instead, to be effective, they need some form of error concealment.
 
Rolf:

You are correct that the encoder itself is not much a source of delay.

The big variable is your distribution server load. The more listeners you have hanging on that server, the larger and larger delay you have. This is in addition to buffering delays at the player level. A shoutcast or WMA server induces a lot of delay as the number of simultaneous users goes up.
 
A properly configured streaming server will not accept more users than it can handle. If the server is being hogged down, it means all the connected users will be suffering break-ups in their stream delivery - what's the point of that? What kind of quality of service do you then offer?

There should be no increase in the stream delay with the number of users connected (right up to the maximum number a server's hardware can handle) apart from the small initial delay due to negotiating - but this is milliseconds...


Regards,
Goran Tomas
 
Goran:

Theorectically you may be correct. But in reality that is not what happens.

Listen to a Clear Channel station over the air and over their WMA streams. As the listener load increases, the delay increases more and more.

This happens with our shoutcast server, as well. The quality is fine, but the cost is an increased delay. During peak listening hours, our Shoutcast stream can be up to three minutes behind our analog FM.
 
Back to the subject of how to serve your local game listeners.... How about a low-powered kit radio that you take with you for the games? http://www.broadcastwarehouse.com/bw-broadcast/all-in-one-1w-fm-stereo-exciter-&-limiter/5/product

or

http://www.broadcastwarehouse.com/bw-broadcast/tx1-stereo-fm-transmitter/22/product

You could turn the power down enough to not get the gov't irritated most likely. You'll want more than part 15 limitations, but if you are careful you can find a clean enough channel and probably get away with it. It's just too bad the burocrats can't get the concept that there is a true need out there for temporary and very localized micropowered stations. There's no reason, other than gov't stiffness, that there can't be a true legal way to drop in temp. licenses at one watt or less in most locations IMHO. Here's a pretty decent resource to see who you could be bothering at any given spot: http://cdbs.recnet.com/lpfm.php Get the reject report of the locations you want to broadcast at and find the best comprise for the right channel to use that causes the least interference to others. I generally use the LP-10 No 3rd adj in the drop down. Good luck!
 
ChiefOperator said:
Many of our listeners take their IPhones to our HS football broadcasts and wish to listen in real time.
Click to expand...

Are you sure about that? iPhones aren't capable of playing WMA streams. Windows-based phones can, but not Apple iPhones.
 
Pocket Tunes will play wma audio streams. It'll also allow you to enter private streams. It's too bad ATT is such a big bumbling company. Technically I bet there's a way to stream right out of a iPhone in some form of Udp that would feed out to others trying to listen to the game etc. It might be interesting for someone to come ip with an app to do just that on the encoder and decoder end for localcasting stuff IF we could get sorry-assed ATT via Apple to allow it. Surely their rickety old system to survive a 18k Acc stream...
 
Higher source bitrates can fix this, however listening on an iphone might be hard unless you have fast 3G, at around 128k there is a 10 second delay usually. increase to 256k and this will go down.
 
The FCC doesn't care about a 5000 watt pirate covering 30 miles in Boston, they will not care about a 1 watt pirate broadcasting inside a basketball court.
Search eBay for a cheap 1 watt FM transmitter, plug it in to the output of your mixer that's also sent out to the broadcast station. You might only be able to have the audio from the court, and none of the audio originating from the studio (commercials, IDs, pre/post game shows, highlights).
 
Yup. Be careful to use a frequency carefully researched like you were going to put a 10 watt LPFM on the air or something. RECNET.com is a great source to poke around and research that. If nothing clears then do a reject report and see who you'll bother and try to find the frequency that you'll logically not bother as much. Make sure your equipment is clean and not over-modulated. There are serveral non-certified transmiters out there but one of the best "kit" transmitters is Broadcast Warehouse. If you have one of their transmitters, and audio limiter of some sorts (they have one with it built in), and a lowpass filter for the output to make DAMN sure you're not talking to the airplanes, chances are you'll never get a visit from the the federal pests. If they do ever come bother you, chances are extremely good that the worst that will happen is they'll take the kit transmitter with them. The first time they come to bother you there will not be a fine. Good luck!
 
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