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tagesmann

Hi Definition Audio

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This is (apparently) the future.

 

 

 

"CD was revolutionary when it first appeared, just over 30 years ago: none of the surface noise of well-played LPs, no annoying ticks and pops caused by invisible scratches, no need to handle the discs with kid gloves – though the early demonstrations of discs smeared with jam still playing were a little over the top! – and instant access to any track on an album at the push of a button. CD running orders could be programmed, favourite tracks repeated and the duff ones skipped, and in time added features such as CD Text readouts of album, track title and artist would become possible.

For all that, CD was always a compromise, using technology that was only just cutting edge at the time. 30 years on, we can do so much better.

"Digital audio encodes the analogue musical waveform, using Pulse Code Modulation. With PCM, the two basic factors that determine the sound quality are bit depth (which determines the quality with which the analogue signal is digitised), and the sampling frequency (which is the number of times per second that the analogue signal is digitised). CD is a 16-bit, 44.1kHz system, what’s needed to improve conformity between the analogue original and the digitised version is a combination of more bits in each samples, and more samples for each second of music: the more bits you use, the more natural the music sounds, and the faster the samples, the wider the frequency range.

CD’s 16-bit/44.1kHz digital system may have been the apparent state of the art in 1982, but it didn’t take long for it to get past its sell-by date. Indeed, some say it was only ever almost good enough for high-quality sound reproduction: Malcolm Hawksford, Professor of Psychoacoustics at Essex University, feels that, ‘It was near the limit, but in my view probably a bit marginal. Ideally, at least 20-bit resolution at 60 kHz sampling frequency would have been better.

However, 16-bit/44.1kHz is what we got back in 1982, and 16-bit/44.1kHz is what CD still uses more than three decades on: we’ve been trapped in a technology ‘almost good enough’ 30 years ago for all that time, just like we would be with everything else we own if all development had been stopped back then.

"Yes, there have been attempts to replace the CD with something better – in the early 1990s not one but two ‘high-resolution’ audio formats appeared, and battle was joined between DVD-Audio and the Sony/Philips Super Audio CD (or SACD), the former offering 24-bit audio quality for greater resolution, improved dynamics and greatly reduced distortion, while the latter’s Direct Stream Digital system used a sampling rate of 2.8224Mhz, 64x that of CD and single-bit sampling.

The new formats also offered the opportunity for multichannel surround sound and greater security and copy protection – one good thing for consumers, it was suggested, and one for the record industry. However, there was a problem or two…

DVD-A discs needed a special player – not just a standard DVD-Video machine – and these were a while coming, while the music retail industry wasn’t keen on stocking releases in multiple formats, and dealing with a hassle of buyers picking up a DVD-A disc by mistake and finding it wouldn’t play on their CD player.

"SACD had an answer to that one: its multilayer discs allowed back-compatibility with CD hardware, which just saw them as standard CDs. Only when used in an SACD player was the higher-resolution layer ‘unlocked’. That meant record stores could sell just one disc for SACD and CD buyers, but then the pitching of SACD as a premium medium would have meant CD prices rising, at a time when deep discounting on music was really beginning to kick in.

What has, unfortunately, made a big impression on the market is compressed audio formats, notably MP3: originally used to allow sensible amounts of music to be stored on early personal music players with very limited storage capacity, MP3 can reduce the size of a music file by around 80% by removing most of the sound you can’t hear – quieter sounds masked by louder ones, for example. Unfortunately along the way it also loses quite a lot of the sound quality you can hear, and while the losses may not be so apparent on lower-quality equipment or when played in noisy environments – on headphones in the street or on public transport, for example, or on standard-fit audio systems in many cars –, when you step up to better audio systems it’s all too easy to hear the reduction in quality.

"The good news is that while MP3 does’t sound too great, it did open up new channels through which music could be obtained – via online downloads.With those channels opened up, Free Lossless Audio Codec – or FLAC – now makes it possible to download music at CD quality or better, or store your CDs on computer or external storage, while saving up to 50% of the file size without losing any quality.

"The clue’s in the term Lossless: FLAC packs music without losing any of the content or quality, and when ‘unzipped’ correctly the file is exactly the same as the original file. And while we’ve seen a number of rival lossless systems, from Apple Lossless (ALAC) to Windows Media Audio Lossless (WMA Lossless), the Free Lossless Audio Codec (FLAC) is the system of choice for many music-loving hi-fi buffs, simply because it’s not tied to any one manufacturer’s systems.

 And it can do more than cut the size of CD-quality files: FLAC can also come in 24-bit form and beyond, as Albert Yong of Bowers & Wilkins explains: ‘The system is so flexible that it can take anything from 4 to 32 bits and sample rates up to 655350Hz in 1 Hz steps.’ he says.

"And FLAC, first introduced in 2001, is opening up a whole new world of high-end, high-resolution audio for enthusiasts: 24-bit digital has a theoretical resolution of 144dB (compared to around 96dB in CD’s 16-bit) which is more than enough, given that 130dB is the threshold of pain for the human ear. That means you can get ever closer to the master-tape used in the studio, as well as gaining all the information made possible by the greater data-rates of these high-resolution files: Albert Yong says ‘The difference is in the detail. Sounds generally are more open, and there is an extra level of airiness in the music. Voice and instruments sound closer to live, and more dynamic as well."

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I have been ripping my music to FLAC for a couple of years now. Lynn stopped selling CDs because they think that an audio file (even at CD standards) sounds better than the CD. They even recommend ripping the CD and listening to the ripped file to get a better sound.

 

Hi-Def audio files are better quality than CDs and I think they sound as good as vinyl. Sometimes they sound better. Vinyl does have it's limitations. Peter Gabriel's album So did not have his preferred track order (In Your Eyes was supposed to be the closing tack) on vinyl because of dynamic limitations. Something to do with not being able to have a heavy bass track at the end of a vinyl side.

 

CDs have issues with their spin speeds. Unlike vinyl which has a constant angular speed CDs have a constant linear speed which means they spin faster for track one (the inner track on a CD) than for the last (outer) track. This can create errors in the sound which aren't present in a disgital file.

 

Hi-Def FLAC files contain more information than a Cd. Perhaps more than the ear can hear. Are they better?

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