Good bye to the CD, hello iTunes

This is both a commercial and a technical goodbye.

Commercial

Commercial, because frankly music these days is downloaded. The Internet has provided a new delivery chain which has by-passed the CD. Revolution in the music business which has for all its life held control over the delivery chain (Vinyl then CD), but which has now lost it to iTunes, Amazon and the streaming services like Spotify. As a side effect of this is the loss of high quality audio. At the moment all popular internet delivery uses lossy compression at various bit rates.

Technical

Now on the technical side. The CD has dominated digital delivery for years. It is a system that captures music at 16bit/44.1kHz sample rates. And this is the feed that is also used to encode the internet delivery in AAC or MP3 at 192 or 320kbps data rates. Recovered audio is at 16bit/44.1kHz.

Future is different

But, future interest is not in the arcane rate of 44.1kHz (where ever that came from), but in using 48kHz, 96kHz and even 192kHz rates. The future is also a wider bit depth of 24bits in place of 16 bits.

1 DAT uses 48kHz, normally 16bit


2 Stereo output (not 5.1) from disks provides 48kHz, 16 or 24bit when not protected by DRM (HDPC on HDMI links to DTVs..., Blu Ray disks etc)


3 The BBC uses 48kHz internally (with a up/down conversion to/from 44.1 at various parts of its delivery chain and output to us - they haven't got their act totally together yet). They use 24 bit at the front end for concert recordings, but downgrade to 16bit along some chains.

You will notice one thing, 96 and 192 are multiples of 48. That means it is much cleaner to down sample from 96 or 192 to 48. But down sampling or up sampling between 44.1 and the other rates is a software nightmare and a noisy mess.

So the CD at 44.1kHz and 16 bits is dead. Now what we need to emerge is a solid way of getting 16 or 24bit/48kHz or 96kHz audio to our homes. This has to be done on the internet.

File choices

The second choice is whether to abandon lossy encoding (AAC & MP3) and stream or download source PCM files (AIF or WAV formats, or lossless ALAC or FLAC formats). Lossless files are x10 bigger than lossy, so it really depends on the progress we make in having a bigger, faster broadband pipe - and that's another story - but it is the future of high quality music to the home. After all the BBC says you need 2Mbps for iPlayer video, so why not use 2Mbps for high quality audio streams?

Apple's not quite there?

Although there is not a lot of official information about the sound channels in Apple iTunes, Airplay (music over WiFi in the home), Apple TV and Apple Airport Express, it looks like all WiFi streaming is done at 16bit/48kHz using the ALAC lossless codec. This is good news, 24bit would be even better...

But iTunes music arrives at 16bit/44.1kHz (CD standard, but with lossy AAC encoding). This makes no sense and it seems to me that they need to revise their AAC delivery to 16bit/48kHz to avoid re-sampling before WiFi streaming using Airplay. All Apple iPods support 48kHz too.

What I would like to see is Apple iTunes have two delivery routes, for iPods etc AAC 16bit/48kHz for low cost music with fast downloads, and 24bit/96kHz lossless at a (slightly) higher price (not x2 as I have to pay for wider broadband width to get it!) for high quality stuff. The 24bit/96kHz could be re-sampled to 24bit/48kHz for WiFi streaming if the Apple TV & Express hardware can support 24bit (the core audio of Macs supports up to 32bit).

They need to push the recording industry in this direction and firm up their own strategy.