Where there's a choice - aac or mp3?

[Dave2002]

Perhaps most of us here would rather have CDs, DVDs or Blu Rays, but sometimes music is available in a choice of download formats. Again, some would only want to have so-called hi-res, while others might settle for less.

Sometimes there are real bargains to be had in download formats, compared with CDs etc., and perhaps only the most dedicated audiophiles would pay more.

Sometimes there's a choice of mp3 (say from Amazon) or aac (probably iTunes). Typically the bit rates might be 320 kbps for the mp3 and 256 for the aac version. While many of us might not hear much difference, and there can also be convenience factors to influence choice, since aac might require conversion anyway to play in some systems. Does anyone feel that aac at 256 offers better sound than mp3 at 320 - or vice-versa?

An example where this might matter (very slightly) came up today with recordings of Mozart sonatas and concertos by Carmen Piazzini which seem a great bargain at both Amazon and also the iTunes store.
(msg 1839, Bargains thread - http://www.for3.org/forums/showthrea...610#post210610)

[Stunsworth]

My understanding is that AAC used more advanced encoding techniques than MP3 and therefore gives better sound at a similar bitrate.

The R3 HD stream I 320k AAC and sounds excellent.

[johnb]

Dave, are you saying that the bitrates for Amazon's mp3 downloads are 320kbps?

Amazon says:

Where possible, we encode our MP3 files using variable bit rates for optimal audio quality and file sizes, aiming at an average of 256 kilobits per second (kbps). Using a variable bit rate allows us to allocate a higher bit rate to the more complex sections of music files while using a smaller bit rate for the less complex sections. The average of these rates is then calculated to produce an average bit rate for the entire file that represents the overall sound quality. Some of our content is encoded using a constant bit rate of 256 kbps. This content will have the same excellent audio quality at a slightly larger file size.

In my experience the Amazon mp3s have been between 210 and 256 kbps variable bitrate.

[mathias broucek]

Subjectively I slightly prefer the sound of 250kbps AAC over equivalent MP3 so I downloaded the Mozart sonatas from iTunes but I've never done a side-by-side comparison.

[jayne lee wilson]

I'm an old fussy I'm afraid - AAC 320 kbps is as low as I go for live streams, and it is pretty good - but anything less than lossless for a purchased download would feel like picking my own pocket (and insulting the ears...)

[Cheapskater]

Absolutely agree with Jayne. I would prefer FLAC downloads, but have had better results scouring the charity shops for CDs (with some excellent bargains to be had e.g. BBC MM Cds seem to be easy to come by)

[Dave2002]

Johnb

I had thought that some of the mp3 offerings (e.g. amazon) were at 320 kbps. Your post indicates that they are not, and that amazon and itunes offerings could have similar bit rates.

Mathias

At the same bit rate aac should sound better than mp3. I'm not quite sure how ogg vorbis fits in. This is the compression used by Spotify. At bit rates 250 kbps and above there's usually not much difference between different compression schemes. I've heard some of Carmen Piazzini's recordings via Spotify - they sounded good enough. I would expect aac to sound similar or better, and mp3 to sound slightly worse. At the compression rates used I might not be able to detect any difference.

Like you, I'd probably prefer aac for quality, though if I also want to play the recordings in my car or on other players the mp3 would be more convenient, and save me having to convert to mp3 or other formats, possibly incurring a further quality loss.

Jayne and cheapskater

At the same or similar price I would generally prefer CDs or a lossless format such as FLAC or ALAC. This is not always what's on offer, and if a download is very cheap then it seems to me to make sense to go for that. I did that with the BIS set of Glazunov symphonies, though later I bought the CDs anyway, thus increasing my overall cost in that instance. However I have a number of downloads where I don't think it's worth upgrading to CD or high bitrate downloads. This applies where I discover I'm not 100% enamoured of the music, the performances or the recording. Sometimes I would pay more, and the original recordings would benefit, but better formats and/or higher bit rates are not available. If there are problems with the underlying recording it does not matter so much about the compression, as with Fedoseyev's Glazunov rcordings. I have reverted to collecting LPs for some of those, as the master tapes have deteriorated, as all the digital copies are compromised.

One other factor in the mix is how well any digital compression is carried out. There are differences depending on the quality settings even for the same bit rate. This is one reason why CDs may offer a better guarantee of quality. I have also sampled some of Apple's Mastered for iTunes tracks, which arguably might sound better even than CDs if you believe that increased bit depth helps. I couldn't detect much difference. My gut feeling is still to go for the CD.

Regarding the performances of Mozart by Carmen Piazzini which triggered my inital post, I think they are much cheaper in either mp3 or aac formats than any equivalent CDs, so therefore a bargain. If I'm wrong in this, I'll look out for CDs. I think the concertos are available on CDs at considerably greater cost. Some of the sonatas are available on a 4 CD box set from Quadromania (Membran) which is relatively cheap, and the recordings date from 1989. I don't know if these are the same recordings as the ones offered by amazon and itunes as downloads. I have had some Quadromania CDs before and I have felt that the audio quality has been variable - though that might have been because of limitations in the masters. I believe the download set is more complete.

[Dave2002]

I'm an old fussy I'm afraid - AAC 320 kbps is as low as I go for live streams, and it is pretty good - but anything less than lossless for a purchased download would feel like picking my own pocket (and insulting the ears...)

Unless you have really superb equipment, which is possible, I rather doubt that you could tell the difference in quality of different compression schemes if done well at bit rates above 250kbps. Please shoot me down if I'm wrong.

One problem is that the differences become more subtle as the bit rates and compression formats improve, and unless you listen under ideal conditions and have very good equipment and also have very good hearing, then it becomes almost impossible to distinguish any differences. This also depends on the music and the complexity of the sounds recorded.

However another problem, which you may be hinting at, is that the conversions done by the distribution companies may not be optimum. Some companies may use poor masters or poor mastering, so that notionally the recordings are 320 mbps mp3 or equivalent aac, and can be measured as such, but if quality is lost through carelessness, then one gets a probably good copy of an already mangled recording.

Price is still a factor though. I would not feel hard done by with the Mozart collections mentioned at the prices offered, even if the quality could be better if FLAC versions were available. Not everyone can afford to pay significantly more for what, to them at least, may be marginal differences.

[Bryn]

Just to gloat a little, I would remind those singing the praises of low cost Piazzini Mozart recordings that I paid just £10 for a 40 CD Mozart boxed set which included her concerto and sonata recordings. This was purchased at the Windsor branch of The Works, though it did emerge that they had priced it in error. It should have been £14. There was also a 20 CD Mozart box for which the price of £10 should have applied. When I bought the set it was pretty much expecting barely acceptable performances. How delighted I was to be proven wrong.