Developing a simple petition for improved bitrates and increased spectrum allocation for DAB+ broadcasting in Australia

[MLXXX]

In another thread there's been discussion of the the rather poor audio quality currently on offer by most of the DAB+ broadcast services in Australia. Here is part of a recent post from that thread:

6 hours ago, Audiofile1503564314 said:

... YES I think we should all petition ACMA, the government and broadcasters - whatever.... otherwise for the first time in human history we'll witness not advancement, but decline.

 

I'd refer readers to that thread in the first instance for background: 

 

Rather than a number of us separately authoring up a form of words I wonder whether we could try to agree in this thread on some basic dot points so that someone can draft a simple easy to understand petition wording. We might then be able to use an off-the-shelf petition site to help gather signatures. Alternatively individuals could contact the ACMA, their local Federal member, et al, directly. 

So I hereby invite dot points!!!

[MLXXX]

As a reference source, this site is very useful for getting an idea of DAB+ bitrates in use around the world: http://www.wohnort.org/dab/

 

Our petition could begin in this way:

With active consideration now being given in Australia to the expansion of DAB+ radio broadcasting into regional centres ( http://www.acma.gov.au/Industry/Broadcast/Spectrum-for-broadcasting/Spectrum-digital-radio/the-acmas-digital-radio-regulatory-roadmap ) we the undersigned request that sufficient radio spectrum be allocated to this endeavour, in order to position Australia for a DAB+ radio network of world class audio quality. If sufficient channels are not made available, broadcasters will be forced to use suboptimal bitrates for encoding the sound, resulting in an emasculated and "tinny" sound emerging from DAB+ radios in Australia.  

We think it reasonable in 2017 to aim for digital radio broadcasts with an audio quality at least comparable to reception of an FM transmission (with a good quality FM radio and antenna, in a good signal strength metropolitan location). If this is not achieved, then the introduction of DAB+ technology will represent a retrograde step compared with FM broadcasting, albeit that it may provide an improvement over AM broadcasting.

The following abstract for the 2013 academic paper Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems [ http://www.aes.org/e-lib/browse.cfm?elib=16969 ] suggests that quite high bitrates are needed to reach FM radio quality:

The perceived audio quality of a digital broadcasting system (such as DAB+) is dependent on the type of coding and bit rates selected. Because of bandwidth constraints, the required number of channels, and conflicting auxiliary services, audio quality is sometimes degraded. In designing a broadcast system, it is necessary to have well-defined criteria for minimally acceptable quality. Two studies explored quality criteria and how quality degrades for various bit rates. For DAB+ the subchannel rate should not be less than the currently available maximum of 192 kbits/s for a stereo signal, which would be comparable to the quality of a modern FM system. Rates below 160 kbit/s can significantly degrade certain types of program material. To be truly perceptually transparent, bits rates of close to 300 kbits/s may be needed when using the current generation of coders.

Although a future digital radio broadcast scheme in Australia might aim for 300kbps we consider that in 2017 a practical bitrate to aim for for a DAB+ service requiring good audio quality, such as a service devoted primarily to music, would be 125kbps.

_________

Comment: The above is in a narrative rather than dot point form, but I hope it may help to set the ball rolling in this thread. A really important issue I feel is what bitrate to recommend for quality music stations. And whether we suggest that as the actual audio bitrate of the particular station or "service" or as the overall nominal bitrate of the service (which includes data for other purposes such as images).

Edited April 7, 2017 by MLXXX

[Audiofile99]

I think it's a good start... Empirical research is important... I think we'll need anecdotal reports as well as empirical research.  Also wondering if it's worth citing requiring more spectrum reserved for future community applications - e.g. community radio.

Edited April 8, 2017 by Audiofile

[alanh]

MLXXX, other than one newcomer, you are talking to yourself. Obviously not many people are worried by low bit rates.

There is no possibility commercially of increasing bit rates on radio due to a lack of spectrum unless DRM+ is introduced so this whole thread is pointess. Best leave the topic alone as there is at least 3.5 million Australians not complaining.

Alanh

[MrC]

8 minutes ago, alanh said:

MLXXX, other than one newcomer, you are talking to yourself. Obviously not many people are worried by low bit rates.

There is no possibility commercially of increasing bit rates on radio due to a lack of spectrum unless DRM+ is introduced so this whole thread is pointess. Best leave the topic alone as there is at least 3.5 million Australians not complaining.

Alanh

Dear Alanh

I do not know you but I was rather taken aback by the tone of your last post.  It came across as high handed, dismissive and rather arrogant.  If this was your purpose, then I can say that you were very successful.  Whilst everyone is entitled to their opinion, I did not appreciate the manner in which you put yours.

[alanh]

Mr C

MLXXX has been pushing this low sound quality now for 7 years. I challenged him to go to a digital radio studio and compare the original source of the sound and then compare it to various compressions where he doesn't know until afterwards what was used. He has not done this. I asked him to go to a car dealer and listen to a DAB+ radio in one of the many new cars as these have better and newer sound systems including much better speakers than the single speaker in his Roberts radio. He has not done this. He did in the early days suggest that DAB+ was worse than a wideband AM radio. Well for a start there is no stereo. and how much of the audience can live within a few km of a high powered transmitter and you could not buy them in a shop even then.

The compression systems used in DAB+ radio were developed in a technical university in Germany where extensive double blind testing was used and a huge variety of data rates using trained and untrained subjects under controlled conditions. Considering that the compression systems now used are lossy systems, they are all based on psychology and so must be tested on lots of people, not just one and one who knows what has been done to the signal.

As I said there is no way the broadcast industry can get more DAB+ spectrum, it wants to move into regional areas and with only 8 DAB+ transmission channels available and the rest of the band is used by TV, what is the point. Will the broadcasters switch off some of their broadcast streams to increase the quality of others? The broadcasters will ask how many listeners want this. Where is the calmour for this change? I suggest you monitor Norway's public broadcaster's Klassic channel for the rest of the year, as more and more of their FM transmitters are switched off see what they do with its data rate.

Alanh

 

 

 

[MLXXX]

3 hours ago, alanh said:

including much better speakers than the single speaker in his Roberts radio.

Alanh, I don't know why you are fixated on the first  DAB+ radio I purchased. I'd remind you it has a pair of speakers not one. And I'd remind you it has been listened to using its line output socket on a good quality hi-fi setup.  I have listened to quite a number of other standalone DAB+ radios over the years connected to high quality audio systems.

 

3 hours ago, alanh said:

I challenged him to go to a digital radio studio and compare the original source of the sound and then compare it to various compressions where he doesn't know until afterwards what was used. He has not done this.

What an unreasonable suggestion that people such as myself impose on the time of digital radio station personnel in such a way! There are HE-AAC encoders readily available online and HE-AAC sample files readily available online to illustrate the progressive decline in subjective audio quality as bitrate is reduced. And in capital cities in Australia there are FM stations that simulcast on DAB+, permitting easy comparisons of the sound quality achieved simply by switching a radio between DAB+ and FM mode for listening to the same station. 

 

3 hours ago, alanh said:

The compression systems used in DAB+ radio were developed in a technical university in Germany where extensive double blind testing was used and a huge variety of data rates using trained and untrained subjects under controlled conditions.

These studies revealed amongst other things that the subjective degradation of a stereo source of music using a bitrate of 48kbps was less severe for most participants when the HE-AAC v1 codec was used, rather than the AAC or certain other codecs.  Here is a typical graph illustrating  such findings (which appears at page 7 of EBU TECHNICAL REVIEW January 2006, S. Meltzer & G. Moser):

 

The full pdf may be found at https://tech.ebu.ch/docs/techreview/trev_305-moser.pdf

I'd note that stations that show as being at 48kbps on a DAB+ radio display are actually operating at a lower bitrate than 48kbps for the audio. (There are overheads that reduce the bitrate available for the HE-AAC audio to a figure below the nominal bitrate of the broadcast, such as data bitrate reserved for slide show images.)

Edited April 12, 2017 by MLXXX

[hrh]

Alanh, is it at all possible for you to not be constantly and consistently attacking nearly everything or anything that MLXXX or a few others post?

PLEASE!

5 hours ago, alanh said:

MLXXX, other than one newcomer, you are talking to yourself. Obviously not many people are worried by low bit rates.

Just because only one person as such has posted DOES NOT mean that ONLY one person is interested. Perhaps the number of views of the thread may have some semblance of interest in it albeit many would be of a cursory interest.
Using your logic back at you I will venture to say, once again, that just because there is three and a half million listeners to DAB+ does not mean that they are all satisfied with what they hear - it just means that they listen to it, good, bad or indifferent. Most of them will be indifferent to the quality of it versus FM or what it should be like with a decent bit rate, and of those who are aware of it, most are willing to just accept it while the remainder, such as MLXXX are not and are willing to put themselves out there and comment on it.
However it seems unfortunate that people as such then come up against those who seem to think that this alleged low quality is a load of old hooey and are basically telling those who are willing to rail against this norm that is being thrust at us, to shut up and accept it.

Now, can we please get back on topic.

P.S.

4 hours ago, alanh said:

He has not done this

Have you?

 

Edited April 12, 2017 by hrh

[Pesto Lovin' Man]

21 hours ago, alanh said:

There is no possibility commercially of increasing bit rates on radio due to a lack of spectrum unless

silly niche filler channels are removed and they stop wasting bitrate on talkback?

Is it really true that DAB+ in the proper cities wastes bitrate on Coles WA & Coles TAS? Tas doesnt even have DAB+ does it so why does Coles TAS even exist?

[alanh]

hrh,

With the exception of the digital only channels and the AM channels if they don't like the quality they can listen on FM. Which they are not doing because this is what they report to the ratings diaries.

It is only Brisbane which has Coles WA and Coles TAS broadcast which is curious because TAS has no digital and Coles WA is not on the multiplex here. ColesWA uses satellite feed of tht program but the the Coles store near me they don't play music in the store.

MLXXX's main concern is ABC Classic FM. So why doesn't he push to get rid of these Coles channels and increase the data rate for 4MBS light?  (Brisbane is the smallest population with 2 commercial/community program streams. Sydney and Melbourne has real broadcasters, and Adelaide and Perth only have one commercial/community transmitter each.

The ABC and SBS have filled their data bandwidth so which programs will the ABC/SBS have the guts to switch off? All of their music programs are 80 kbit/s except Unearthed which is72 kbit/s. Why should ABC Classics have better sound quality in theory than say ABC Jazz or JJJ where the younger audience could more easily hear the high frequencies? They have not allocated any data rate for images or the Emergency Warning System audio and data even if they are the emergency broadcaster! Grant Broadcasters have operated the EMS system in Darwin where the Emergency Services produced the content and it was automatically transmitted.

 

MLXXX, the EBU extract is not the one from Frauhoffer which shows many different bit rates. All the one you show is that other compression standards are pretty poor at that data rate. So what is the result for 64 and 80 kbit/s? There is also no comparative test with FM compared to the same originals.

I should also add that different sounds have different difficulties in compression. You are yet to describe which sounds give you trouble and describe how they are changed.

 

Alanh

Edited April 13, 2017 by alanh
different sounds

[MLXXX]

6 hours ago, alanh said:

Why should ABC Classics have better sound quality in theory than say ABC Jazz or JJJ where the younger audience could more easily hear the high frequencies? They have not allocated any data rate for images or the Emergency Warning System audio and data even if they are the emergency broadcaster!

I'm not sure whether your reference to allocating data rate for images is intended to refer to the DAB+ service ABC Classic FM. The last time I looked at the image data rate allocation for ABC Classic FM as broadcast in Brisbane on DAB+ radio it was significant. And that is common with DAB+ in Australia.  The actual audio bitrate is usually significantly less than the nominal bitrate. (Some actual figures have been cited on this forum in the past.)

 

6 hours ago, alanh said:

MLXXX, the EBU extract is not the one from Frauhoffer which shows many different bit rates. All the one you show is that other compression standards are pretty poor at that data rate. So what is the result for 64 and 80 kbit/s? There is also no comparative test with FM compared to the same originals.

Yes AAC plus SBR was not as bad as many other codecs at 48kbps (actual) at the time of the study which of course is why it was chosen over certain other codecs to be part of the DAB+ broadcasting standard.  A lot of the reported testing has been for 48kbps (actual) and 64kbps (actual) but as noted in the report I quoted in post 1, much higher bitrates would actually be needed to attain FM quality.

I recall seeing few if any reports of listener trials for HE-AAC at 80kbps. I think that was because HE-ACC's greatest performance dividend is at lower rates like 64kbps and 48kbps. As you may recall, by the time the bitrate has reached around 96kbps (actual), SBR is more of a detriment than a benefit and is typically not used: the encoder defaults to low complexity or "plain" AAC.  

 

6 hours ago, alanh said:

I should also add that different sounds have different difficulties in compression. You are yet to describe which sounds give you trouble and describe how they are changed.

I think if you were to re-read posts from 6 or 7 years ago you would find that I have gone into some detail in the past about the unsuitability of low bitrate HE-AAC for my hearing and described what I heard in certain sample recordings I uploaded. I don't feel inclined to go back and find those posts at this stage. What I am thinking of doing is making some sample recordings over the next few weeks of current DAB+ broadcasts, uploading some of the material, and inviting comments from interested forum members. 

Edited April 13, 2017 by MLXXX

[hrh]

16 hours ago, alanh said:

With the exception of the digital only channels and the AM channels if they don't like the quality they can listen on FM. Which they are not doing because this is what they report to the ratings diaries.

The reason why they are listening to the DAB+ service needs to be told, not just they are listening to it instead of the FM.In my instance FM reception is extremely poor without careful placement of the contained/extending antennae. The only real way for a decent signal to noise ratio - particularly for a stereo signal - is to use an outdoor one, ie the TV antennae and that is too much stuffing around. Therefore I would listen to the DAB+ service which has ample strength.
The reason behind something always needs to be taken into consideration.

Now, enough of this and get back to the topic. If you wish to take it further, take it to the appropriate thread or start a new relevant one - unless of course if your aim is to disrupt nearly every thread that has something you don't agree with, you are doing a bang-up job.

[MLXXX]

12 hours ago, MLXXX said:

The last time I looked at the image data rate allocation for ABC Classic FM as broadcast in Brisbane on DAB+ radio it was significant. And that is common with DAB+ in Australia.  The actual audio bitrate is usually significantly less than the nominal bitrate. (Some actual figures have been cited on this forum in the past.)

Well I had time for a quick look this afternoon. ABC Classic FM was operating at around 64 kbps for the audio, as reported by the Andreas Gsinn player. Here is a screen capture from my pc:

[alanh]

Demonstrate your knowledge of HE AAC codec. Why is the bit rate less that 80 kbit/s, what does the Audio Total mean?

Alanh

[MLXXX]

14 hours ago, alanh said:

Demonstrate your knowledge of HE AAC codec. Why is the bit rate less that 80 kbit/s

It appears that at the time I was receiving the nominal 80kbps broadcast, around 7.5kbps was used for overheads involving error correction, around 8.4kbps was used for "Program Associated Data" including in this case text (the weather forecast and station slogan) and an image (a slide showing the ABC logo); and around 64.1kbps was used for the HE-AAC v1 audio.  

At the start of DAB+ broadcasting in Australia a number of us observed that the sound quality for the bitrates shown on our radios was less than the quality we heard with various sample files available on the net at such bitrates. We suspected that some of the bitrate was lost to overheads and to reservations of data for slides but didn't know how much.
 

For people interested in a technical overview of the DAB+ broadcasting system, this 2013 presentation document by Dr Les Sabel may be useful: https://www.worlddab.org/public_document/file/442/DAB__Overview_2013.pdf?1394188480    

 

14 hours ago, alanh said:

what does the Audio Total mean?

Alanh, you query what was meant by the Audio Total of 657KB. It appears to represent the cumulative amount of audio data received for the service since it was selected by the user to listen to. Similarly the figure of 86.0KB appears to be the cumulative amount of PAD received since the software defined radio was set to receive the particular service. (I had only been listening to the service for a short time when I took the screen snapshot.)

[alanh]

MLXXX,

So your sample was only 10 seconds long, what was the sound?

You don't have to give me quotes from 7 years ago usually of what others have said.

If the audio is so bad now, describe what you hear now, what sound has the problem and what does it sound like.

Alanh

[MLXXX]

9 hours ago, alanh said:

If the audio is so bad now, describe what you hear now, what sound has the problem and what does it sound like.

Alanh, subjective impressions of low-moderate bitrate HE-ACC have been described on this forum multiple times by me, and by others, in the past. Nothing has changed for me.

I presume you yourself can hear artefacts at very low bitrates such as around 12kbps. If so, just imagine hearing those sorts of artefacts, not as pronounced, at around 64kbps (actual) HE-AAC. That is a guide as to what I hear.

Demonstration file

There is a downloadable 123MB wav format demonstration file on the following webpage:  http://a-bc.co.uk/audio-quality-comparison-dab-pcm-fm-am/  

The worst sounding codec examples in that file are HE-AAC v2 encodings in stereo at 16kbps and 12kbps. The 16kbps segment is announced at 4 min 26 sec into the file. It is immediately followed by the 12kbps segment announced at 5 min into the file. Please listen to these two segments. If you cannot hear artefacts in the 12kbps stereo segment, then you have extremely tolerant and non-discriminating hearing!

 

On 4/14/2017 at 4:01 PM, hrh said:

The reason why they are listening to the DAB+ service needs to be told, not just they are listening to it instead of the FM.In my instance FM reception is extremely poor without careful placement of the contained/extending antennae. The only real way for a decent signal to noise ratio - particularly for a stereo signal - is to use an outdoor one, ie the TV antennae and that is too much stuffing around. Therefore I would listen to the DAB+ service which has ample strength.
The reason behind something always needs to be taken into consideration.

Good point, hrh. In fringe reception zones the hiss from FM using a portable radio in the home can be very distracting and not everyone can be bothered to connect to an external antenna mounted on the roof, as we are used to doing for TV.  

In the car, in addition to hiss there can be annoying multipath reception glitches with FM.  On the other hand, around town FM reception in the car can be remarkably good. I find that my last two cars have shown greater resistance to multipath than earlier car radios. I find I can get reasonably low noise FM reception on the highway heading north from Brisbane at a distance up to about 25km from the Mt Coot-tha transmitters, with most of the FM stations.  Beyond that distance, the higher powered FM transmissions, such as ABC Classic FM, have a distinct advantage.

Edited April 16, 2017 by MLXXX

[alanh]

,MLXXX,

So you cannot describe the imperfections you hear on DAB+ radio today by describing what you are listening to and what the effect is?

I am not interested 12 kbit/s. I am interested in the music coming from ABC Classics, ABC Jazz, ABC Country, JJJ and ABC JJ now. Not quotes from others. Your experience now.

I am not interested in FM, only DAB+

Alanh

Edited April 16, 2017 by alanh

[MLXXX]

If you are unwilling to search for my previous detailed comments, and uploads of comparison files, I am unwilling to do so.  Nothing has changed in a material particular since I made my comments years ago.

Edited April 16, 2017 by MLXXX

[alanh]

MLXXX,

I don't want you to search your previous comments. I want you to describe what happens now. You keep complaining of low quality and cannot describe it on current broadcasts. If not it does not exist.

That being the case you must stop complaining.

Alanh

[MLXXX]

17 hours ago, MLXXX said:

Demonstration file

There is a downloadable 123MB wav format demonstration file on the following webpage:  http://a-bc.co.uk/audio-quality-comparison-dab-pcm-fm-am/  

Something other forum members may find of interest is the simulated AM sound that starts in the above wav file at 5m 13s. It is of somewhat better quality than I am able to receive in Brisbane in respect of one parameter: distortion. Even with a software defined radio I find that the THD when receiving Brisbane AM stations is quite noticeable. I have found distortion worse with recordings I've been able to discover on the net of AM stereo. The distortion is reasonably euphonious particularly if higher audio frequencies are suppressed. I tthink that is one reason that wideband AM radios are virtually non-existent: they tend to reveal too many distortion products.

If AM radio had  even less distortion when received than the demonstration file exhibits it might have proven more attractive to the public in its basic mono form. And stereo AM might have taken off with lower audible distortion. I have yet to hear any recording of off-air AM stereo that did not include a somewhat unpleasant degree of distortion.That's for my hearing. Other people might be more forgiving!

Edited April 16, 2017 by MLXXX

[MLXXX]

On 4/13/2017 at 9:08 AM, Pesto Lovin' Man said:

silly niche filler channels are removed and they stop wasting bitrate on talkback?

I think another thing to consider to increase the bitrate available for music services would be to pare back the allocation for PAD. I'm not sure exactly how this works but I suspect that if the PAD bitrate were reduced it would still allow a basic slide to be displayed. It might just take longer for it to load when a user selects the service.

 

In another thread I  have posted the current actual audio bitrates for all of the DAB+ services being broadcast in Brisbane. Some of the services use a much higher PAD rate than others, significantly reducing the bitrate available for the codec compressed audio:-

 

[alanh]

Why increase bit rates when you cannot give any examples of your own of poor sound from existing Brisbane DAB+ stations? Considering that many of the stations are networked with identical data for all mainland state capitals. So we can receive the same signal and come to our own conclusion. There is no point in resampling it to put it on this website because resampling introduces distortions of its own.

When will you give current examples quoting the sound that is bad and what is wrong with it, the broadcaster and when it was broadcast?

So what does poor THD sound like? What sounds did you hear it from?

Alanh

Edited April 17, 2017 by alanh

[MLXXX]

3 hours ago, alanh said:

There is no point in resampling it to put it on this website because resampling introduces distortions of its own.

Incorrect. Resampling is a routine operation. For example recordings of symphony orchestras may be multi-mike recordings captured at 96KHz 24 bits, subsequently mixed at 96kHz 32 bit floating point, and then finally resampled to 44.1kHz dithered for a CD master.

[alanh]

MLXXX,

Yes and the CD is of worse quality. The 44.1 kHz sample rate is so it can be locked to NTSC video which is no longer used in the USA. AAC uses 48 kHz sample rate which is half.

More importantly the down sample is synchronised so exactly each alternate sample is removed. Dithering is trying to cover up the distortions created.

Stop changing the subject.

Why are you avoiding my question. I will have to soon conclude that you cannot detect any poor sound quality caused during the broadcasting of DAB+ programs. This will mean that the broadcasters have selected an appropriate data rate for the program content they are transmitting.

Alanh