the sound performance?

[Sgeirk]

I just finished up re-doing an entire station library. With most audio from Jones TM. Not all. Linear, delivered as wav files...backed it all up elsewhere, too. It's good to be linear and it's good to have a backup. 1000 songs might occupy 10% of a 750 gig HD...no coding...crazy to use any compression for audio when I see a 750gig HD going for $119 at Fry's....an example, nonetheless.

CC stations are hogtied with their means of WAN distribution. They can never go linear...their WAN would grind to a halt ...FLAC wouldn't help much, either...CC station's HD streams always sound inferior.

A real good HD stream from a station that really has it together can sound amazing. It all goes back to the source audio, period.

One more thing, this isn't the first time I've heard someone say that a CD rip is NEAR CD quality. I don't get it. How can it be anything BUT cd quality?

 

[TomT]

In my example of recording a CD then saving as a .wav file, as opposed to an mpeg-3 encoded file, would result in a nearly identical copy of the original CD. Attempt to keep the example simple for our original poster who is as fluent in English as I am in digital technology. "Nearly identical" because you would have to consider imperfections in the digital to analog decoding from a CD player, then the limitations of the sound card. I use the the "low-end" Audio Science cards for automation playback machines--and I can hear a coloring to the sound when you run audio into record and directly back out to play, as you might in some automation set-ups. (Our production studio computer has a Digigram card for this reason).

By the way, some folks like to build their library this way, manually riding gain in order to have more consistent levels song-to-song off the hard drive. More power to them. Dubbing Christmas music this fall I can see why--there may be 30 db in difference in the average level between a CD remake of a '60's era recording of choral music and a contemporary CD of [current pop star] sings for the holidays.

I would agree that "ripping," that is, simply converting the information on a CD in the digital domain to the linear wav format; should result in a file that would sound identical on playback to the original CD. Although somebody is sure to post a detailed description of why it won't.

 

[CW]

CC stations are hogtied with their means of WAN distribution. They can never go linear...their WAN would grind to a halt ...FLAC wouldn't help much, either...CC station's HD streams always sound inferior.

A real good HD stream from a station that really has it together can sound amazing. It all goes back to the source audio, period.

Very true for CC....they primarily use Prophet's system (owned by CC) and it defaults to MPEG-2 5.5:1 compression ratio.. I hated that!! One of their stations that had an AudioVault (from AMFM) had NO compression and all the songs were WAV...GAWD did they sound great on the air....once NexGen took its place, the music never sounded the same..MPEG-2 has loss in the low and middle range....doing an A-B comparison to a CD of the same song, there was NO comparison....the CD blew it away. In HD, everything MUST be 44.1kHz sampling so that means the automation audio is either played as analog then digitized to a 44.1kHz format OR must be digitallly up converted and that NEVER sounds good...

WAV with plenty of HD space is the only way to go....(BTW as to levels, you can normalize the level if you need to thus loosing dynamic range but help boost some older, wide range recordings...Audacity does this and you can even normalize only portions of whatever you are working on)

 

[LA_Guy]

MP3 gain normalizes CD's. It simply looks at the entire MP3 file from end to end, and adjusts the baseline gain so the loudest peak on the cut reaches a level just below clipping.

As such it is not processing as we classically know it.

MP3 gain is a good thing to do to your MP3 files.

 

[LA_Guy]

CC stations are hogtied with their means of WAN distribution. They can never go linear...their WAN would grind to a halt ...FLAC wouldn't help much, either...CC station's HD streams always sound inferior.

A real good HD stream from a station that really has it together can sound amazing. It all goes back to the source audio, period.

Very true for CC....they primarily use Prophet's system (owned by CC) and it defaults to MPEG-2 5.5:1 compression ratio.. I hated that!! One of their stations that had an AudioVault (from AMFM) had NO compression and all the songs were WAV...GAWD did they sound great on the air....once NexGen took its place, the music never sounded the same..MPEG-2 has loss in the low and middle range....doing an A-B comparison to a CD of the same song, there was NO comparison....the CD blew it away. In HD, everything MUST be 44.1kHz sampling so that means the automation audio is either played as analog then digitized to a 44.1kHz format OR must be digitallly up converted and that NEVER sounds good...

WAV with plenty of HD space is the only way to go....(BTW as to levels, you can normalize the level if you need to thus loosing dynamic range but help boost some older, wide range recordings...Audacity does this and you can even normalize only portions of whatever you are working on)

Clear Channel uses MP2 (MPEG1 Layer 2-NOT to be confused with MPEG-2) encoding at 256 kbps. They also run their levels down 10 db below clipping.
Starguide also uses MP2, but at 128 kbps and with the levels run right TO clipping.
Part of the problem is that there just aren't a lot of good MP2 rippers/encoders around-it's a very old format. Use a decent ripper like SUPER and you'd likely retract your statement.

Of course, a good compromise would be to use FLAC for encoding. It's a 2:1 LOSSLESS coder.

 

[RolfTaylor]

"Of course, a good compromise would be to use FLAC for encoding. It's a 2:1 LOSSLESS coder."

Or use Enhanced apt-X (or other ADPCM) which is 4:1 near lossless - Less than 8% data loss versus 75% loss for a psychoacoustic algorithm (MPEG Layer2, 3, AAC, Vogg, etc) operating at 4:1.

For this reason it is the perfect compliment to HD since it cascades so well with other algorithms.

It has been more-or-less a well kept secret of the post-pro industry until recently.

Rolf Taylor
Applications/Support Engineer

APT North America

800 955-APTX (2789)

www.aptx.com

 

[stace]

Up until recently our flagship station in Auckland we're playing all music off CD and commercials from Prophet Wizzard, made life very easy for the Omnia6. All stations are now on Nexgen, and all our music is sent via WANcast. Not cool

 

[rrsounds]

<snip> In HD, everything MUST be 44.1kHz sampling so that means the automation audio is either played as analog then digitized to a 44.1kHz format OR must be digitallly up converted and that NEVER sounds good...</snip>

Regarding sample rate conversion, I think that "NEVER sounds good" is a bit of a blanket statement. IMHO there are varying quality levels with different sample rate converters, as with anything.

Besides, you can't avoid sample rate conversion. Every digital broadcast audio processor that I know of has at least one, or even more SRC (s) in the program path.


Kind Regards,
David

 

[RadioFixerCLE]

If you want quality, ditch the mp3s and start broadcasting wav files.

Most mp3s sound awful on air.

Or even better....just play the music right off the CDs on the air. Why make things much more complicated? ???

It's that much less crap you're subjecting the audio to.

 

[OKCRadioGuy]

Play stuff off CDs? NO WAY! How could they voice-track stations and make 3 people run 5 stations in a market that way? LOL!

 

[rrsounds]

If you want quality, ditch the mp3s and start broadcasting wav files.

Most mp3s sound awful on air.

Or even better....just play the music right off the CDs on the air. Why make things much more complicated? ???

It's that much less crap you're subjecting the audio to.

Hi Stephanie!
Complicated, you say?... The process of finding the CD, putting it in the machine, and then finding and cueing the desired cut is just way too time/labor intensive. Never mind that there has never been a really good broadcast CD player. A hard-drive based system lets the operator concentrate on more important things, such as what he's going to say. Or that precocious little 14 year-old he gave the hotline number to.

Individual hard drives are not entirely reliable either, but you can put several of them in a RAID and get (theoretical) 100% reliability. As others have said, no need for any data reduction. And it's fully automation (or live assist) ready.

As you may have noticed, as part of our mandate, we (engineering) take on more complication in our realm in order to reduce it in the operators' realm. it has been this way since Day One, and many of us actually love (and seek) the challenge.

Kind Regards,
David

 

[Tom Wells]

In the process of recording my latest AM 1620 aircheck podcast,
I'm listening with headphones to an air-monitor that's roughly flat to 15khz or better, and I'm really trying to hear my 128 k artifacts.

I only hear them on files where I have downloaded a 128 from somewhere, or re-ripped such a file.
I do not hear it on stuff I dubbed from vinyl.
In fact, everything sounds better on-air than direct off the audio card.
This points to the cascading of codecs as being the real problem.
I see the same things in printing when someone re-uses an existing "half-tone" and the screen interference pattern shows up as something
like a grid at 1/2 the resolution of the original (if they are/were the same screen size).
I can hear that the 192k files sound better, but the 128s still far exceed the frequency response given AM these days.

Perhaps the answer is higher resolutions in the STL.

 

[busyradioguy]

I agree that playing stuff direct from CD, is too labor intensive. There are/were a few automation systems that could handle this task, by using those mega sized CD Jukeboxes (i.e. Wintrax could control the Pioneer 300 disc jukeboxes and some other automation systems could use the Sony CDK series mega changers), but you still have to deal with the maintenance issues.

I agree with everyone who says linear .wav is the way to go. There is no reason not to use .wav files.

 

[DudeFan]

Tom:

You are right about the issue being cascading. Anything in 128kbps mp3 will absolutely fall apart on an encoded webstream. If your signal path has a layer of encoding, it will fall apart. Our minimum for accepting mp3 submissions is 320kbps, with linear .wav file preferred.

 

[gtomas]

MP3's are notoriously bad when more codecs are cascaded, but other lossy codecs are not much better either... In a research done at BBC where they did listening tests with several typical real-life codecs being cascaded (such as a journalist making a field recording in MP3, or an outside broadcast done through ISDN codec, going into the radio station's automation, possibly coded STL and then broadcasted in DAB) the conclusions were clear. Two main things that determine the final audio quality are the 1) source quality (an MP3 recording going through several coding/decoding processes deteriorated severally worse than an uncompressed source going through the same chain) and 2) bitrate of the final transmission codec (in this case, MPEG-1 Layer II as used in DAB). In this research, 192kbps of the final transmission codec was considered still OK, while bitrates below that caused a serious loss in audio quality (falling from "perceptible, but not annoying" to plain "annoying" on a BS-1116 scale).

The newer codecs such as aacPlus (used in DAB+, DRM and web streaming) and HDC (used in HD Radio) are better in a way that they are more efficient, but at the same time they are also being used with lower (actually, very low) bitrates. Which kind-of negates the benefits... The main point is though, that with the move to (coded) digital transmissions it's even more important to have your audio sources of highest audio quality, because at the very end there is always a codec operating at the (very) low bitrate.

For Internet streaming there's a chance for this bitrate to increase in the future as networks bandwidths increase (more fibre, more people get last-mile ADSL2(+) or high-speed cable, mobile networks exploit 3G capabilities more, etc). But for fixed digital broadcast systems such as HD Radio and DAB(+), there is not much chance of improvements (other than killing the analog FM or move to another spectrum, both very unlikely IMO).


Regards,
Goran Tomas