HD-1 Processing

[Ai4i]

Two schools of thought on this.
Set the HD-1 to perfectly match the analog in every way or set it to match the analog in time, and peak volume.
We hate to hear a station fade between analog and HD with no improvement:
the same roll off to 15 KHz and the same heavy processing even though there is no noise floor with which to compete (that is/was the purpose of compression).
HD-1's should have a "wow" factor but having them sound exactly as the analog, they could be promoted as, "get a radio with HD technology, we promise it will sound every bit as good as the radio you have now"
We are unimpressed with the former school of thought.

 

[nd2023]

When you're driving around the HD signal will fade in and out, and it is annoying to hear the processing fade in and out.

 

[tomservo]

I don't think it's possible to match the analog and digital EXACTLY simply because of the noise floor difference. I'm close enough to the towers to get "full quieting" on the analog but it's still a noticeable difference between that and the digital. When the digital feed has a quiet passage, it's quiet.

There is another benefit to matching the analog sound on the HD-1, rolling off the highs a little lessens the harsh metallic artifacts of the compression.

One less I don't think has been learned yet re: subchannels is that just because it's a digital or nothing environment, that doesn't mean to use NO processing. We still flip through the radio dial, and going from loud quashed analog/HD-1 to super quiet HD-2 is just as annoying as bad HD/SD blend. The subchannels don't have to be mish-mashed to an inch of their lives like the main channel, but they CAN be a little louder, folks. I'm looking at you, public radio stations.

 

[satech]

There is another benefit to matching the analog sound on the HD-1, rolling off the highs a little lessens the harsh metallic artifacts of the compression.

Exactly. Only stations which are not transmitting any subchannels (HD2 / HD3 / etc.) have the luxury of adjusting their digital processing to achieve a desired sound. It is on those few stations where you may here some improvement compared to the analog, such as wider stereo separation and a brighter, more open high end.

Otherwise, the primary goal of HD1 processing becomes trying to match the analog texture while minimizing codec artifacts. Especially in fringe areas where the receiver is going to be constantly blending back and forth between analog and "HD", you don't want the crummy low-bitrate digital audio to be even more of a "tune-out" than some hiss and static already is for analog listeners.

As I became all too familiar with this past month, Christmas music is especially difficult to squeeze through low-bitrate digital compression, because the high end transients of jingling bells often comes out sounding totally shredded. Try taking some audio of a Salvation Army bell ringer and run that through your "HD" stream at 32 kbps -- the sound will come out completely unrecognizable!

 

[Ai4i]

Sounds like the best thing to do is to process the HD1 for analog and then take the output of a digital receiver or mod monitor and drive the analog input. I still like hearing a station pop into HD and experiencing the "wow" factor.

 

[nd2023]

Sounds like the best thing to do is to process the HD1 for analog and then take the output of a digital receiver or mod monitor and drive the analog input. I still like hearing a station pop into HD and experiencing the "wow" factor.

Why degrade the quality of the analog signal for 99% of the listeners that don't have HD radios? Sometimes the station's own stream sounds better than the HD1.

 

[Ai4i]

Analog should NEVER sound better than HD1.

 

[tomservo]

Analog should NEVER sound better than HD1.

Depends on your definition of better. Around here, Cheap Channel's audio is already highly compressed on a few of their stations, so when it's run through the HD encoder, it breaks down even more. The high end roll off of the analog hides some of the artefacting but the HD brings it through with great clarity. Therefore, the analog actually sounds better.

I'm particularly sensitive to the compression noises introduced, so it's annoying to me to hear it sound even worse. The same thing happens to these stations that stream online. The compressed music is being re-encoded for online distribution and sounds terrible.

No offense to you old timers, but I swear most engineers have tin ears. Streaming online or upgrading to HD should not happen unless the music distribution system is upgraded to lossless audio. I don't know what formats modern radio software uses, but raw WAV or FLAC or a really really efficient codec with a lot of overhead should be used instead of 128 kbps mp3 files.

 

[radiogooroo]

Two schools of thought on this.
Set the HD-1 to perfectly match the analog in every way or set it to match the analog in time, and peak volume.
We hate to hear a station fade between analog and HD with no improvement:
the same roll off to 15 KHz and the same heavy processing even though there is no noise floor with which to compete (that is/was the purpose of compression).
HD-1's should have a "wow" factor but having them sound exactly as the analog, they could be promoted as, "get a radio with HD technology, we promise it will sound every bit as good as the radio you have now"
We are unimpressed with the former school of thought.

Personally, I'm a huge fan of limiting dynamic range for both analog and HD. Why? Think of where people use radio - in cars, in offices, while brushing their teeth in the morning. The "noise floor" of a typical radio listening environment is compromised far more by ordinary background noise than by the actual noise floor of analog technology.

 

[Ai4i]

Another poster on these boards says that studies show that something like 30% of listening is done while driving and even so, would your belief not depend on the type of music the station plays? Also, YOU do have the option of buying a processor and putting it in YOUr audio chain (impossible to unprocess processed cheese or music).

 

[Chuck]

YOU do have the option of buying a processor and putting it in YOUr audio chain (impossible to unprocess processed cheese or music).

Yeah, but if you think stand-alone HD radios don't sell very well, an add on processor would be an even bigger turkey on the consumer market. They would simply be more trouble than 99.99% of listeners are willing to go to.

Even serious classical music stations use some sort of processing.

 

[tomservo]

YOU do have the option of buying a processor and putting it in YOUr audio chain (impossible to unprocess processed cheese or music).

Yeah, but if you think stand-alone HD radios don't sell very well, an add on processor would be an even bigger turkey on the consumer market. They would simply be more trouble than 99.99% of listeners are willing to go to.

Even serious classical music stations use some sort of processing.

That's a shame, I always thought it'd have been smarter to put basic processing electronics on selected radios to let the consumer choose how much they want to screw up the sound, instead of letting some tin-eared engineer or Type A GM insist on ruining it for everyone.

Today it's irrelevant since practically all new music and most remastered old music is squeezed to within an inch of its life.

 

[Chuck]

That's a shame, I always thought it'd have been smarter to put basic processing electronics on selected radios to let the consumer choose how much they want to screw up the sound, instead of letting some tin-eared engineer or Type A GM insist on ruining it for everyone.

I think you overestimate the ability of most consumers to figure it out, even if it were available.

 

[tomservo]

That's a shame, I always thought it'd have been smarter to put basic processing electronics on selected radios to let the consumer choose how much they want to screw up the sound, instead of letting some tin-eared engineer or Type A GM insist on ruining it for everyone.

I think you overestimate the ability of most consumers to figure it out, even if it were available.

I know, I know. I see the older Delco radios with the 5 band EQs all smashed as high as they will go. *sigh*

But I don't care about other stupid people and how they screw up their audio. I only care about what I do it myself, and how it comes to me. It's why I just about won't buy mp3s unless there's no other way to get the music. I want it raw, uncompressed and un-"remastered" if at all possible.