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Developing a simple petition for improved bitrates and increased spectrum allocation for DAB+ broadcasting in AustraliaBy 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:
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!!!
According to my rough calculations which are based on publicly available data, DAB+ accounts for just under 20% of all radio listening in the 5 mainland state capitals (19.9%) by time spent listening. What’s more, the whole-of-audience time spent listening to DAB+ (DAB+ audience x time spent listening) has increased by over 5% in each of the last two DAB+ surveys of 2016.
As a comparison, the share of radio listening for DAB/DAB+ in the UK in the 2nd quarter of 2015 was 26.7%. It was 31.2% the same time in 2016. It was 19.1% in the 12 months to June 2012, so Australia’s 5 mainland capitals are only four years or so behind the UK. Not bad given that Australia officially launched DAB+ 14 years after DAB was launched in London and 11 years after it was launched in the rest of the UK.
If anyone can supply me with a link to an official file considered to represent "FM quality", or an official definition, I'd be obliged. Over the years I've seen many references to "FM quality" but no actual definition, or sample file.
My own experience is that using an older horizontally polarised external TV antenna connected to a medium quality AVR in a high signal strength metroplolitan reception area provides me with reception with a subjectively very good audio quality. For my ears, for a range of program material, it is markedly better than 48kbps DAB+, somewhat better than 64kbps DAB+. For my ears for classical music, it is noticeably better than 80kbps DAB+. I've found a modern car FM radio can also perform well, though with greater noise and subject to occasional glitches from multipath reception as the car moves along the road.
The poor audio quality of real life DAB+ and real life DRM relative to FM radio in a high signal strength reception zone has been mentioned a number of times on this forum over the years. I do not however recall the following research paper having been mentioned or discussed. I happened across it today and thought some forum members beyond myself might find it to be of interest, despite it having been published back in 2013!
Research published in 2013 concluded that a very high bitrate was required to achieve FM quality. This was certainly much more than the 48 or 64kbps commonly used in Australia for DAB+, or the even lower audio bitrates commonly used internationally for DRM30 broadcasting. Access to the full paper requires payment of a fee or possible free access at the discretion of the authors. For the purpose of this thread I will merely rely on:
1. The freely available abstract of the paper.
2. Comments from two sources, being observations by people who have read the paper and prepared relatively formal remarks.
Off we go then!
1. The abstract, accessible at http://www.aes.org/e-lib/browse.cfm?elib=16969:-
Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems
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.
Berg, Jan; Bustad, Christofer; Jonsson, Lars; Mossberg, Lars; Nyberg, Dan
Luleå University of Technology, Piteå, Sweden; Swedish Radio, Stockholm, Sweden; Swedish National Laboratory of Forensic Science - SKL, Linköping, Sweden
(See document for exact affiliation information.)
2. Comments at http://www.radiojackie.com/im/Digital%20radio%20AES%20research.doc
DIGITAL RADIO – AES RESEARCH
An important new study has been published in the Journal of the Audio Engineering Society: Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems.
Many different music and speech samples were used in listening tests with the conclusion that a bit rate "close to 300 kbit/s" is required to avoid falling below FM quality.
Neither UK-type DAB (from 1985) nor DAB+ (from 2007) are capable of offering this.
This research is significant for two reasons.
- For the first time, comparisons are made between digital radio and realistic FM radio.
- Processed audio was used, rather than unprocessed sounds.
Processed audio (e.g. 'Optimod') is universal in radio.
Previous work, with unprocessed sounds, had suggested the necessity of 320 kbit/s
to pass the perceptual transparency and statistical undetectability point.
This was adopted by the BBC in 2010 for HD Sound in iPlayer.
These results with processed audio dispel the notion that the sound quality presently possible via digital radio is found inferior by only a tiny minority of audiophiles.
This new evidence, specifically examining everyday radio audio, supports the view that DAB has a role as a supplementary platform but could never prove satisfactory as the sole outlet over the airwaves.
Trevor Brook - 11 November 2013
Surrey Electronics - radiofax.org - Editor: radiojackie.com
3. Comments at http://www.engineeringradio.us/blog/2013/11/what-bitrate-is-needed-to-sound-like-analog-fm/
What bitrate is needed to sound like analog FM?
By Paul Thurst, on November 25th, 2013 7 comments
As it turns out, 300 kbp/s or greater. At least in critical listening environments according to the paper titled Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems (.pdf) published by the Journal of the Audio Engineering Society. This work was done by group in Sweden and made various observations with different program material and listening subjects. Each person was given a sample of analog FM audio to listen to, then they listened to various audio selections which were using bit reduction algorithms (AKA CODEC or Compression) and graded each one. The methodology is very thorough and there is little left for subjective interpretation.
In less critical listening environments, bit rates of 160-192 kbp/s will work.
[Note: The article immediately above goes on to provide a detailed table.]
I personally am not at all surprised at the reported findings!
Thanks to Ozabargain.
For those who may have missed this deal. Kmart currently have the Audiosonic Nora Mantle DAB+ portable radio on clearance for $9.
Preset and save up to 10 Radio stations each DAB+ and FM band.
Alarm with sleep functionality
Rechargeable Lithium Battery (not removable)
4-6 hours playtime
Earphone jack (confirmed stereo out)
Powered by AC/DC adaptor (Micro USB included)
Open in Google Chrome and get it to translate it
German Kulture Digital radio is increasing its sample rate from 96 to 112 kBit/s and they are transmitting in 5.1 surround sound. http://translate.google.com.au/translate?hl=en&sl=de&u=http://www.deutschlandradiokultur.de/&prev=search shows they are using DAB+
DRadio Knowledge from 88 to 96 kBit/s.
Lets now see if you can tell the difference between this and your antique AM radio on the transmsitter fence line of 612 ABC Local radio.
With Malcolm Turnbull announcing his intentions to free up some of the TV spectrum for other uses, e.g. mobile broadband, I would like to put forward some ideas on how this could be done.
I have read elsewhere that MPEG4 would allow the same video to be encoded using half the bitrate, while DVB-T2 would allow the bitrate to be increased. On that basis, the number of channels required for any area would be reduced from 6 to 3 (already mentioned by others, e.g. here, This would free up 15 channels. Given the block structure of our channel allocation, this would mean freeing up three channels on VHF (could be used for expanding digital radio) and 12 on UHF (which could be used for freeing up 610-684 MHz for another digital dividend).
What about H.265, which I've read requires half the bitrate again compared to H.264? Would this reduce the channels required per area to 2? This could free up another 5 channels, e.g. one channel from VHF and four from UHF, or we could dispense with the VHF band altogether for TV, freeing up 2 UHF channels, or just use them as unallocated channels. H.265 may be awhile off from being a viable alternative but we could start planning for it, moving to MPEG4 first, then switching to H.265.
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