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The Debate


Sounds Good To Me

OK. What debate? For the vast majority of people, there's nothing contentious about the subject of digital audio file formats. On the one hand, we have MP3; popularly enshrined as the standard digital audio file format to the extent that it's become practically synonymous with downloaded music. Look at any mention of an iPod or Walkman in the mainstream media, and they'll still describe it as an MP3 Player, whether or not it's actually used to play MP3s. With DRM-Free MP3 the format of choice for download services from Amazon, Play and 7digital, it's a format on the rise, not on the wane. On the other hand, we have AAC. Whether you love Apple or hate Apple, AAC remains the default choice - and sometimes the only choice - for the millions who buy into the company's iPod line, its iTunes media player or its iTunes Online store.

If you take music and sound quality seriously, however, then audio formats and compression rates are things that probably matter to you. At TrustedReviews we regularly criticise DAPs and PMPs for their failure to support lossless formats like FLAC or WMA Lossless. We have readers who comment after a review that they wouldn't buy a specific player for exactly the same reason, or because it doesn't have the raw capacity to handle their library of FLAC or Apple Lossless tracks. There are still people who eschew digital downloads, buying albums on CD so that they can rip them themselves and ensure optimal quality (that would be me - ed). While I personally don't go that far, I can state that I've avoided buying tracks from certain online stores for the specific reason that the MP3 format tracks they sold were encoded at 256kbps and not 320kbps. To my mind, the extra quality was even worth paying a little extra cash for.

Recently, however, a few things have left us wondering whether we've been placing too much emphasis on the importance of lossless compression and specific file formats, particularly when it comes to purchasing music or listening to it on portable devices. First, like most people we've spent a lot of time using streaming services like Napster and Spotify. The former uses 256kbps MP3 files for download tracks and 128kbps MP3 files for streamed tracks, while the latter uses 160kbps OGG Vorbis (though premium users can upgrade to 320kbps). While high-end headphones or speakers can show up some deficiencies of the low bit-rate formats, we couldn't describe the sound coming out as appalling. In fact, it's usually 'good enough.' Secondly, a few people in the last six months or so - people who take their audio gear seriously and have spent thousands of pounds on Hi-Fi equipment - have admitted privately to us that 256kbps MP3 is easily good enough for serious listening, and that they struggle to hear much difference over 192kbps MP3 in many situations. This got us thinking: when we claim that we can tell the difference between a 320kbps MP3 and a FLAC encode, are we really hearing some substantial difference, or are we merely telling ourselves that one is better than another?

We decided it was time to find out...

Ada Mari Frost

June 14, 2013, 6:07 am

High quality FLAC sounds warmer than MP3. Most people equate the warm sound to not being crisp, that's how you get a lot of people thinking the MP3s are better.


January 4, 2014, 1:41 pm

Those are the worst graphs ever. The axis are so poorly labled that I can't understand what they are supposed to show.


February 16, 2014, 2:40 pm

This article is a few years old now and out if date, but even taking that into consideration......

Unless I missed it, no mention was made of the MP3 decoder being used. They're not all created equally in respect to accurate decoding. WMP had a poor decoder prior to version 7. The Winamp MP3 decoder prior to version 2.666 was known to be substandard.

Constant bitrate is never going to be the best method for audio encoding any more than it'd be the best method for encoding video.

Bitrate is not the only variable which effects quality. The LAME MP3 encoder has settings for CBR encoding which use different algorithms and result in different encoding speeds at exactly the same bitrate. The encoding time for 5 minutes of stereo audio using my (aging) PC is around 7 seconds for the LAME default of q3, and 38 seconds for q0 (CBR 192k, LAME 3.99). The article makes no mention of the quality setting used.

From version 3.99, LAME's CBR encoding uses the PSY model from the VBR code. Even today, at the same average (lower) bitrate, CBR encoding will never match the quality of VBR encoding, bitrate. Back in 2009 it was possible it wouldn't even at very high bitrates.

The golden eared folks over at hydrogenaudio have a page dedicated to LAME which states any of the LAME VBR presets from V3 to V0 should normally be "transparent". ie it's not possible to distinguish the MP3 from the original. The average bitrate for V3 is around 175 kbps. For V0 it's 245 kbps.

The article refers to lossless audio and bitdepths/sample rates higher than those used for CD sounding better. A claim which seems to have been debunked.

Hannes Minkema

June 8, 2014, 2:00 pm

"Only one person could accurately pinpoint which tracks were MP3 and which tracks were FLACs in every case."

I appreciate the effort, and I believe the general conclusion is about right. Yet it is unwarranted to state that only one person *can* (or *could*, which is the past tense of *can*) accurately distinguish MP3 from FLAC. The statement should have been that only one person *did* this. But this, by itself, says *nothing* about his general capacity to do so.

This is not nitpicking. I am sure that many readers misinterpret this statement, and believe that this one guy actually has better ears than all the rest. Heck, you might even believe this yourself. But there is no proof of that.

Take one hundred people. Ask them to draw the Queen of Hearts from a stack of playing cards. Two, maybe three of them will do so at the first draw. How is that possible? Should we conclude that they are psychic? Of course not. They are just lucky.

Take one hundred people. Ask them to tell which of two playing cards is red, and which is black. Fifty of them will be totally right at the first guess. Ask these fifty people to do it again. Twenty-five will succeed. Ask them again: twelve of them will be so lucky as to perform the trick thrice. Six will do the trick four times in a row, and three are so 'psychic' that they manage to guess right five times in a row. Incredible! Not.

They have no special gifts, of course. They are just assisted by blind chance. The next time they are put to the same test, they most probably won't be so lucky. So far for their 'general capacity'.

During the MP3-to-FLAC trials, the one guy who was able to guess right four times out of four trials was assisted by blind chance either. You can't erase blind chance. That's why scientific inductive statistics take 'blind chance' into account. And that's why the statement 'one guy *could* do it' is misleading. He couldn't. He just did. The combination of his ability AND blind chance did the trick. But that's not the same.

The question was not if one person *could* distinguish MP3 and FLAC, but whether a more general null hypothesis was rejected or not. That null hypothesis would be that out of seven people trying four times to distinguish MP3 from FLAC, a greater number of guesses turned out to be correct than can be accounted for by blind chance, with an uncertainty of less than 5%.

Anyone with a scientific training could have told you this. It is Statistics 101.

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