Members of an audiophile forum, Hydrogenaudio made a test of audio codecs at 64 kbps. If you haven’t followed the progress in this field (like I didn’t), you’re probably surprised why did audiophiles choose something as low.
The answer is simple: modern codecs (like aoTuV ogg Vorbis) are practically transparent at 128k – that is you can’t tell the difference between the original and encoded files.
And when you look at the 64k results, when listeners rated samples from 1-5, the winner, CELT (soon to be renamed to Opus), got an average score of 4. Not bad for 64k, huh? Certainly overkill for my phone player.
What makes me sad is that ogg Vorbis was a clear looser, not only it used the most space (all codecs are VBR, so exact bitrate differs), but also got the worst sound. It’s the top dog at 100+k, but apparently it doesn’t scale to bitrates this low. This makes me question Google’s choice to allow only Vorbis in its latest WebM video format with no plans for more. It makes it easier to ensure decoders are compatible and Vorbis is great for HD movies, but there are many uses for codecs that trade quality for size and there are more than a few around the web.
I really hope Matroska adds support for VP8 (WebM video codec) in MKV files…
And I wonder what comes next. How far can we squeeze bitrates? How far will we squeeze bitrates? Disk space keeps getting cheaper, so do bandwidth and CPU power, so incentives get smaller and smaller; even if there’s plenty of space for improvement it will stop being worth it.