Listening Comparisons For Audio Codecs At 64kbps

waaka! writes "Hydrogenaudio has just wrapped up a listening test of various audio codecs at 64kbps. Check out the results, where Ogg Vorbis performed quite well, scoring significantly better than WMA, RealAudio and QuickTime AAC, and kept pace with MP3Pro and HE-AAC (AAC with the SBR extensions that MP3Pro uses). Clearly, though, no codec can honestly claim 128 kbps MP3 quality at 64 kbps. The charts at the end show entries for 128kbps LAME MP3 and 64kbps FhG MP3, but these are used as high and low anchors for reference, as MP3 is really out of its league at bitrates such as these."

Comments

some good listening test material

[MarcoAtWork]

I saved this thread quite a while ago and I agree with several of the recommendations (notably with the 'Tori Amos' 'Boys for Pele' CD, not that it's the type of music I usually listen to, but I have to admit the production values are outstanding), after all using hyper-compressed (re: other slashdot articles) crappy source material is not that helpful in terms of figuring out how good the various encoders really are...

the thread on google

Personally I rip my own CDs with lame --alt-preset extreme (on said Tori Amos' CD it seems it hovers around 224kbps with -lots- of frames at 256 and 320), for fun I transcoded (I know, transcoding is bad, mmkay?) a few of them to vorbis 48kbps and it's amazing how good they sound at that low of a bitrate.

Re:some good listening test material

[default luser]

(I know, transcoding is bad, mmkay?)

Actually, it's not as bad as you think, given the circumstances.

The general problem with re-encoding audio is errors will become magnified versus a direct encode to the lower bitrate. If you take a 192k or 160k CBR mp3 encode and downsample it to some other format, it is going to sound like crap. But you have to remember that modes like LAME --alt-preset virtually eliminate errors in audio reproduction.

Sure, the inaudable tones have been removed, but every bit of the audible spectrum has been accurately rendered, making it nearly as good as the original source for the purposes of transcoding.

I rip all my albums using --alt-preset standard, and I transcode them to 128k ABR for my handheld mp3 player. I've never been able to hear any perceptible difference between this and a direct-from-CD 128k ABR encode.

Why so low?

[Izago909]

Anything below 128k/s (in my opinion) is only good for streaming and embedding. Even 128 is the bare minimum for anything that sounds decent. Are there any comprehensive articles that deal with comparing high encoding rates (192+) of multiple formats?

It should also be noted that it is not recommended using CBR encoding with OGG. It is a native VBR codec that is only forced into CBR for steaming. The quality of CBR is much lower than VBR. It would be very nice to see a comparison that uses VBR for all codecs that stick to the same bitrate range.

Re:Just Habit...

[hondo77]

Try 128 AAC. I can hear that it's better than 192 MP3 even through my dinky little headphones. Better sounds and smaller files make me a happy guy.

Digital Music artist perspective

[merlin_jim]

As an artist that releases mainly online, I found these results very interesting, and thought I'd share my feelings with the slashdot community.

While MP3Pro and Vorbis were good competitors overall, and have a fairly good footprint to boot, I'd have to say that if I'm forced to encode to 64MBit/s, I'd absolutely choose Ahead HE AAC, if I'm judging solely on this comparison (which I am at this point in time...)

Why? Because there was no sample that Ahead HE AAC did POORLY at. MP3Pro and Vorbis (and all the other codecs) each had one or two samples that they just totally choked on, quality-wise. So if I was forced to use a 64 MBit/s codec, it would absolutely be Ahead HE AAC, because while it didn't score highest on every test, and the three codec were virtually tied across the whole competition, I would feel far safer trusting my best digital work to a codec that, according to this test, would have the least chance of representing it particularly poorly.

I wonder how these results compare to higher encoding rates; I could easily imagine that most codecs have a sweet spot, where the encoding quality/bitrate maximizes... it would be interesting to do some research to find this sweet spot.

Anyone want a quick way to slashdot a server? :D

Re:MP3 is the standard.

[StaticEngine]

The Game Industry has embraced OGG, although somewhat silently. With slim budgets, we're always looking for the cheap (and free) solution, and OGG is perfect when we want compressed audio at a good quality.

The sole deciding factor in whether or not compressed audio really gets used in a game is available minspec bandwidth. If marketing is forcing us to target a 500MHz machine, and decompressing OGG audio kills our framerate, then audio compression goes. It the sad truth that the tech heads do not call the shots in this department.

SBR

[zurab]

It's worth pointing out that at least MP3Pro and HE-AAC from tested codecs use SBR. SBR is a method (mostly post-process) that allows transmission of lower half of audio spectrum, and have the decoder "guess" what the the other part of the spectrum would have been. While this allows for "cool-sounding" audio at low bitrates, the generated part of the spectrum is not actually an encoded original audio, but rather its "guessed" reconstruction. SBR is also patented.

Search for more info on SBR if interested, like this one.