Question for station engineers regarding audio bitrate

[islanddxer]

I've noticed in recent years stations using what sounds like a low bitrate MP3 as their airchain. If any of you happen to live in Suffolk County, WJVC 96.1 (formerly WKJI) and WRCN 103.9 were recently sold to another company and they have changed the airchain to sound like a low bitrate MP3 with a fake sounding high end.
I know it's probably not the airchain but the method of STL. I really dont know what this company "JVC" is using, but it seems few other people are bothered by it. Since I listen to the radio through headphones, the switch to low bitrate audio has caused me to switch the station.
I'm no engineer but would like to hear from a few as to why radio stations get away with putting such "low-fi" audio over the airwaves.
It almost sounds like they are using streaming audio. I know most stations use Microwave or Fiber STL's, but why the use of such low bitrate?

 

[bigtom101]

I'm no engineer but would like to hear from a few as to why radio stations get away with putting such "low-fi" audio over the airwaves.
It almost sounds like they are using streaming audio. I know most stations use Microwave or Fiber STL's, but why the use of such low bitrate?

Its cheaper to use a bit reduced codec over the Internet to get audio out to the transmitter site rather than a leased line like a T1 or ISDN thru the phone company. As to why it sounds like garbage, the audio processor is bringing out the artifacts in the audio, rather than masking them. Either they need to jack up the bitrate or do some conditioning to the audio at the studio before it hits the encoder (whats known as pre processing).

A microwave STL would be great, but they may not have access to a tower to put a dish up.

 

[bossbill]

Those using digital compression to feed transmitters ought to not have a license.

 

[islanddxer]

The studio is in Ronkonkoma and the transmitter site atop Rock Hill in Manorville, it's about 18-20 miles as the crow flies. The company (JVC) already owned 105.3 WPTY and 98.5 WBON, which broadcast from an SBA tower off Rt.111 in Manorville (same area).
They purchased 103.9 WRCN and 96.1 and the site is another tower nearby.
I dont know what they are using for WPTY and WBON, but those sound fine. I do remember STL issues in the past when work was done on the SBA site, but I do believe they are microwave, there is a tower on the roof of the building where the station is with dishes.
I guess they still have to get things set up. But when 'RCN's studio was moved the audio was still fine, but now it's messed up like 96.1's.
Sounds like they are using a streaming STL. It's bad enough they use streaming for remotes now, the quality is inferior to the old analog style remotes.
As you can see I'm no fan of streaming, although there's plenty of internet stations out there that broadcast in clean 128k audio so I dunno why these guys cant.

 

[gtomas]

I'm suspecting they are using Barix boxes or something else that is either lower quality and/or low bitrate. I'm would agree with Mr. Wolfenbarger above.


Regards,
Goran Tomas

 

[OKCRadioGuy]

There's reasons people use the bit-reduced audio, but I agree it's not REALLY broadcast quality in most cases. I have two stations that we're doing it with. They don't sound bad, but there is a bit of artifact. That's compounded by any artifact-infected source material. We have the advantage that the majority of what we run it talk programming. It always comes down to cost and somewhat convience. In our case, we can't trust the phone company to keep stuff running. Also, cost is a factor for us. We could take a ride on a internet system that is in place that connects to both markets so it was worth the compromise. I agree the Barix units on the air isn't a good solution unless it's an emergency. They are prone to do wierd things from time to time, and mp3 isn't a good compression scheme in the year 2011. There's a station in town that uses Barix units and the public internet for a music radio station. At best, it sounds like ass. They really should be using a normal STL of some sorts.

 

[oldiesstation]

I have a station using the new Barix 500's doing pcm 44.1 and paired with nanostation 5 wireless radios.Pretty darn amazing.Sounds alot better than the old STL doing composite.MP3 ok for talk,would never use it for music for STL.IMHO as usual..Original files are 44.1 pcm...

 

[ironbear]

Perhaps someone using the Barix products with mp3 coding might jump in here and spill about how they actually sound.

There are lots of mp3 software codecs around, and they vary widely in sound and audio bandwidth at a given bitrate, which you can see if you put the reconstructed audio on a spectrum analyzer. LAME seems to be the apparent best at this time.

So what happens to golden ears if I use a Barix as an STL at...say...128 kbps?

 

[ironbear]

I have a station using the new Barix 500's doing pcm 44.1 and paired with nanostation 5 wireless radios.Pretty darn amazing.Sounds alot better than the old STL doing composite.MP3 ok for talk,would never use it for music for STL.IMHO as usual..Original files are 44.1 pcm...

Oh, didn't see you there! Thank you. OGG is pretty awesome vs. mp3 at lower bitrates, I wonder if Barix might consider easing that into the product line down the road? Plus, no licensing cost (apparently.)

 

[oldiesstation]

i have a friend using the highest bit rate for MP3 in the Barix 100 encoder.But the source audio is 44.1 pcm so it's a one pass encode.He uses the Nanostation M5's (Not the internet) and really likes the way it sounds.I'm just old fashioned and prefer 44.1 for STL applications. I did inquire about FLAC which would work on a T1 and leave some room for data.They said they would consider it,why not,it's open source.

 

[RolfTaylor]

If the source is compressed that is just not wise these days, and IMHO stupid.

However, for the STL there are some difficult decisions. Remember, it is the compression ratio, along with the chosen algorithm that matter (that and together with processing, as mentioned).

Remember, the input sample rate to the codec is under your control. Often 32 kHz makes a lot of sense, and 44.1 (if an option) is a better choice than 48 kHz. Another factor to consider is stereo vs mono. You can halve your input bit rate by going mono vs stereo. Or, you can consider a compromise here and use joint stereo. Remember not all joint stereo schemes are very good.

Finally, as the compression ratio climbs the codec choice becomes more complex. At 4:1 MPEG Layer 2, apt-X, and AAC are all good choices.

Once you get to 8:1 to 12:1 Layer 3 and AAC become your best options.

Above 12:1 AAC is your best bet. I won't even mention ratios greater than 14:1 other than mention they are not, IMHO, remotely broadcast quality.

All of this is in regards to a single pass for an STL. If you are running syndicated programming (or remotes) odds are your STL will be the second or third round of coding. In that case, the choices get that much harder!

 

[BobOnTheJob]

Those using digital compression to feed transmitters ought to not have a license.

Oh for the good old days when we actually had to proof the air chain to minimal standards....the described air chain wouldn't pass AM standards based on the description. Add me to your list of Amens Bill.

 

[Tom Wells]

I'm annoyed when I hear one of my older 128k mp3 files, I now find 192 the minimum acceptable to me, and that is only ONE layer of codec going into AM mono.
It really is horrifying when you hear 2-3 codecs mashing up the program material.
I'd rather hear old POTS lines. Dull but not grating or outright weird-sounding.

 

[OKCRadioGuy]

In linear mode, I'm sure the Barix sound great. I haven't tried that yet because I haven't had that kind of bandwidth to play with, but it sounds like a good solution. You know, if a guy was running over public internet and had to do things totally on the cheap, setting up a streaming computer at the studio running ACC encoding and using a Barix Extreamer 100 to decode the ACC stream would be much better than MP3 or MP2.

 

[oldiesstation]

it would sound better.i just don't like depending on the net for stl delivery.But it's a risk we all take.The barix 500 linear mode is killer application...

 

[OKCRadioGuy]

Yeah. Other than a backup feed, I don't play the true public internet STL game. We have the same provider that is at a point of presence within the market we are broadcasting from. From there it's either composite STL or a T-1 linear link. It's almost a private system, but with some other traffic on it, and it's huge and fiber-linked.

 

[stacker]

Has anyone played with a pair of Comrex Brics? I had a pair of Access units that I've used for years to shuttle audio over IP. So far, good luck with them.

I've always had to rely mostly on ISDN to get audio to my various stations. No direct STL path available. On the ISDN, I run some older Intraplex units that are encoding/decoding MPEG layer 2.

As Ma Bell continues to retire/outplace more and more of their "gray hairs" in this area, keeping the ISDN circuits in good condition is getting to be a problem. Don't have broadband access at all transmitter sites yet, but when it arrives, I'll sure look at that option more closely. Investing in a point to point virtual network is probably the way to go, since your data won't be routed to Tierra del Fuego and back.

 

[OKCRadioGuy]

Att in many areas can't seem to keep Isdn running, as you say because of the gray-hairs retiring out. That's one define reason too why I went IP-based. If it takes bubba the tech 3 days to get the Isdn back and running, it sure can put the hurt on a station. In my case I've got option a and b. Both are IP. Nothing is 100 percent 100 percent of the time like good 'ol analog STLs, where there's a path. My remote stations, there was just no way.

 

[littlejohn]

We've been using a pair of BRICs to supply syndicated programming to an affiliate for several months. So far, they work well.

 

[chriscollins]

Usually, when these things sound really bad, the source material at the studio has come from an already reduced mp3 or a second generation mp3. You would be suprised how many young production people save everything as mp3, thinking it sounds better. I had to have a class at my stations explaining that everything should be a pcm wav...