how many channels on hd radio at acceptable quality

[chriscollins]

I know TV is a different beast, but it makes me wonder... How many other people hear it the way I do? Especially women. They are so much more sensitive and perceive high frequency energy differently. I wonder how HD Radio comes off to a group of 25-45 year old women? I'm sure the 12-17 would think it's good, as they have grown up on bit reduced material.

I wonder that as well. But nobody is doing the research... The results could be surprising!

On one of the conferences I attended, there was a presentation on the results of an extensive test on the perception of the perceptually coded material. There is this huge myth that young people are so accustomed to perceptually encoded music, that they don't notice the difference to linear audio, or even, that they prefer the coded versions. Well, this blind listening test with students, completely debunked this assumption.

If enough independent research is done, the perception on encoded audio quality might be quite different than what the codec and product manufacturers like us to believe...


Regards,
Goran Tomas

That is interesting (and good) to hear). I encounter so many young listeners with low bit rate stuff and it is acceptable to them. I was worried that being raised on this 'sound' might cause the true recording to be the thing that sounded 'odd' to young people.

 

[RadioEngnr]

I seem to remember one of the stations in Philadelphia is running an HD4 program. Is a road trip in the budget?

Doesn't one of the stations near Pittsburgh also do an HD-4..

Yes, WLTJ and WRRK in Pittsburgh have HD-4's
I'm streaming my HD-4 for you to listen to, but bad news.... its all Christmas
This is encoded at 24kbps in Stereo for the Importer (HD-4 Broadcast)

and your listening on-line @ 128kbps AAC+ (by means of a Sangean HDT-1 HD Receiver connected to the Streaming Audio Computer)

http://69.95.45.82:2000/listen.pls

 

[gtomas]

and your listening on-line @ 128kbps AAC+ (by means of a Sangean HDT-1 HD Receiver connected to the Streaming Audio Computer)

http://69.95.45.82:2000/listen.pls

When are people going to understand that it makes no sense (and it sounds bad) to use AAC+ at 128 kbps!?

AAC+ or HE-AAC, is designed for very low bitrates - meaning bitrates at or below 64 kbps, like 48 kpbs, 32 kbps, etc. Not 128 kbps! AAC+ (HE-AAC) uses Spectral Band Replication technology, which means that the higher half of the audio spectrum is always artificially regenerated in the decoder. Hence the metallic and gritty high-end. This happens at any bitrate, 128 kbps included! Which is why AAC+ (HE-AAC) can never be transparent.

(In this case, metallic and gritty high-end also comes for the source, which is the 24 kbps HD4 channel, that is encoded with PAC codec that also uses SBR technology).

Cue in AAC, which is a different codec to AAC+ (HE-AAC). Sometimes in the encoders it's labelled AAC LC, LC standing for Low Complexity which is the most commonly used AAC profile.

To repeat for the millionth time, AAC+ (HE-AAC) is not the same as AAC! And AAC is designed for high bitrates. Higher being at or above 96 kbps. Like 128 kpbs!

Now AAC is a good, solid MDCT encoder that encodes, transmits and decodes the whole audio spectrum without any fancy manipulation of any part of the spectrum. It's vastly improved over the MP3 and is in fact the best audio codec on the market, which is why it's so heavily used in HD television as a partner to H.264 (sounds like TV guys know better sound than radio guys). Because it uses no fancy artificial tricks, AAC can be transparent and according to MPEG, achieves transparency at 128 kbps.

Take away message - if you're encoding at 128 kbps, use AAC! AAC+ is designed only for very low bitrates!

Rant over...


Regards,
Goran Tomas

 

[RadioEngnr]

okay.... I changed the streaming bitrate to MP3 @128kbps

and streaming MP3 sounds 100% better

 

[RadioEngnr]

okay.... I changed the streaming bitrate to MP3 @128kbps

and streaming MP3 sounds 100% better

Reason why for MP3... I had people say they can't decode the AAC

Also I tried your method, and your right it sounds great in regular AAC. I been schooled on the difference

then I tried streaming MP3, I should have used that from the start

 

[bradgoehl]

WJFK run's HD4, I've gone ad far as HD3 but i wouldn't advise it unless you are simulcasting AM or some form of talk. Even at that the quality can get sketchy.