Which audio format is for me?

January 8, 2007 8:43 PM

Which format/bit rate should I store my music to get the most out of my er6 headphones? I want to get the best audio quality but with the lowest file size.

Which format/bit rate should I store my music to get the most out of my er6 headphones?
I want to get the best audio quality but with the lowest file size.

So I'm guessing a lossless codec is not for me. I'm using a 20gb iRiver, that is running the open source firmware called Rockbox. It pretty much supports every kind of obscure format.

Right now I have my music stored in aac+ 48bit, which is great for listening on my phone, and keeping on my laptop since the file sizes are nice and tiny. But I understand that if I want to get the best audio experience out of my shiny new earphones I would want to use a different format. Inform me of your wonderful codecs!

posted by Coolcan2 to sports, hobbies, & recreation (22 comments total)

For the best listening experience, you need to use a lossless file format. For a reasonable compromise try something in the vicinity of 128-256kbits/sec.

A good excercise is to take one of your favorite songs and encode it in a number of different formats, at various bitrates. Listen to each of them, and decide which has the best quality/size ratio.
posted by b1tr0t at 8:53 PM on January 8, 2007

I lean more toward putting a selection on my iPod rather than a whole collection, so the idea of putting 40 lossless FLAC albums at a time on the device outweighs having to sync it more often to get different material. In general, the decision is to use either lossless or not. At the highest bitrates in MP3 and AAC, they're going to sound pretty similar.
posted by rhizome at 8:54 PM on January 8, 2007

The mp3 scene can be a good guide for producing good quality rips that balance file size.

See this for more information.
posted by WetherMan at 8:59 PM on January 8, 2007

What are you listening to, and how much do you need to store?

Generally speaking, you're not going to notice the compression of MP3 at 192 kbps; and unless you're going abroad without your laptop, 20 gigs will give you more than enough space to pack your music. But for the record, there's not much point in fussing over the fine points between compression formats if you're going to be listening with in-ear headphones.
posted by cribcage at 9:00 PM on January 8, 2007

For .mp3, I like the LAME encoder with the alt-preset-standard compression settings.
posted by box at 9:01 PM on January 8, 2007

Warning: blatant self link...

Even so, I wrote about exactly this on my blog.

Conclusion: 128kbs VBR AAC is the best mix of file space and audio quality.
posted by sindark at 9:02 PM on January 8, 2007

Apologies if this is grumpy, but your question doesn't make a lot of sense, as it stands.

#1: You're asking for two opposite things at the same time. Better audio quality generally means larger file size, and smaller file size generally means lower quality audio. Generally you decide what tradeoff you are willing to make -- better sound quality but fewer songs on your device, for instance. You haven't given us any guidance about where you fall in that continuum.

#2: The particular headphones you're using have very little to do with the previous issue. As long as it's not totally crippled somehow (like an old transistor radio speaker with a pencil stuck in it), just about any sound reproduction device will sound better if you feed higher-quality audio to it.

#3: I'm not sure what "AAC+ 48bit" means. What is the data rate you're using? 48 bits of what?

#4: Where is your source audio coming from? CDs, MP3 files you downloaded from Napster five years ago, old 8 track tapes, or what? There is no point in going for some ultra-wonderful codec if the source audio isn't any good.

#5: Do you have the originals in a lossless format? If not, there's no point in converting from one lossy format to another; you'll only get worse results.

#5: If you really care about the audio quality, lossless may well be what you want. It's worth a try, anyway.

As with most things audio, your best bet is to try a few different settings and see if you can tell any difference. (And be aware that it's very easy to fool yourself into thinking you DO hear a difference, unless you are really careful about matching levels and doing a good double-blind test -- which few people bother to do.)
posted by xil at 9:03 PM on January 8, 2007

But for the record, there's not much point in fussing over the fine points between compression formats if you're going to be listening with in-ear headphones.

I usually like what you say about music/audio/whatnot, cribcage, but in this case I must disagree. In-ear headphones have come a long way. Etymotic's in-ear phones are comparable to Shure's--both get excellent reviews, and lots of folks think that the Ultimate Ears in-ear phones are among the best headphones available period (that said, I find in-ear phones desperately uncomfortable and have never worn any of them for more than a few seconds) (and that said, if you argued that big drivers win out due to simple physics, I wouldn't contradict you).

I was going to say, however, that there's not much point in fussing over the fine points between compression formats if you're satisfied with 48k aac+. I'm not a big audiophile, and I don't have great ears, but I find those kinds of bitrates very hard to listen to. Like others have said, though, high audio quality means large filesizes. It's always a tradeoff (another tradeoff--.ogg is more processor-intensive than .mp3, so, at least with my iRiver-running-Rockbox, it meant reduced battery life), so do your own listening tests, using the er6's, and find out what you prefer.

Forums like HydrogenAudio and Head-Fi are a good source of additional information.
posted by box at 9:19 PM on January 8, 2007

Raw CD data is 1,411,200 bits per second, and a typical CD is about 650 megs. 320k/sec MP3 is about 1/4 of that. Very, very few people can hear any difference. If you want to trade off close to zero quality, but cut your filesizes by 3/4, use 320k MP3.

If those files are too big, LAME with --preset standard usually averages 160k to 170k/sec. It's variable bitrate, so that's not terribly precise, but it'll be close to that figure. Very few people can hear MP3 artifacts at this compression level. I sometimes can, and so I generally go for the next level up, --preset extreme. That averages about 220k, and even on very good listening equipment, I can't tell it's MP3 at that level.

(I think the command line options in LAME have changed recently... I believe -v 0 is the old "--preset standard", and -v 1 is "--preset extreme". You'll want to verify this in the docs. )

At 320k, you should be able to fit roughly 100 albums in 20 gigs. At 160k, you should be able to fit about 200.

If you have a very great deal of music you want to fit onto your player, AAC has the reputation of sounding better at the lower bitrates, like 128k/sec. At 128k, you'd probably be able to fit something like 300 albums.

Basically, decide how much music you want to carry with you, and choose the highest possible bitrate that will let you put that much music into 20 gigs.
posted by Malor at 9:24 PM on January 8, 2007

I have a pair of ER6i's and pretty decent ears. 192kbps mp3 or AAC seems to be a good compromise between size and quality for me.
posted by flaterik at 9:38 PM on January 8, 2007

Since you dropped over $100 on headphones, I'd suggest looking in the 192kbps --> 256kbps range with either a good AAC encoder (iTunes was supposed to be pretty good, last I checked), or LAME. In that range most people can't tell the difference between the encoded version and the original CD. Of course you are just one person, so I'd suggest doing your own listening test with a range of songs at a range of bitrates. You might be able to get away with 128kbps AAC, you might need lossless. You won't know until you try.

Since you are using Rockbox, you could also try other formats, including things like Musepack and MonkeyAudio, which, if I remember right, also deliver great quality at higher bitrates.
posted by Good Brain at 10:07 PM on January 8, 2007

As others have said, do some blind tests for yourself (but there's no need for double-blind, IMO). It's the surest way to answer this question. I use 192kb/s vbr AAC and LAME-encoded MP3 (alt-present-standard or alt-present-extreme) with my Sennheiser headphones. Both formats sound good at those bitrates, although I have a slight preference for AAC, which is transparent to my ears, whereas MP3 is not. In your case, be aware that higher bitrates will drain your battery faster.
posted by smorange at 10:21 PM on January 8, 2007

lame -V0 --vbr-new

Nothing else is good enough or small enough.
posted by majick at 10:23 PM on January 8, 2007

Another vote for V0.
posted by sixacross at 10:27 PM on January 8, 2007

third vote for V0. if you need instructions on how to do this in itunes on a mac, respond and i'll post those.
posted by Señor Pantalones at 10:43 PM on January 8, 2007

Whatever format you choose, definitely make sure you are using VBR (variable bitrate) and not CBR (constant bitrate.) If you encode a file using CBR, that means that every frame uses the same equal amount of bits. The encoder has no choice in the matter. However, if you choose VBR, it means that you give the encoder a target budget and it gets to decide how to use it. So frames that have fewer details (or are silence) can use a low bitrate and frames with a lot of detail can use a high bitrate -- much higher than the average. For example if you encoded the file at 192 kbit/s VBR, some frames might use 64 kbit/s and some might use 320 kbit/s, but the overall filesize will average out such that it should be approximately 192 kbit/s for the whole file. By letting the encoder choose the bitrate in this way you get a file of the same size as if you had chosen CBR, but better quality.

I have my music stored in aac+ 48bit, which is great for listening on my phone, and keeping on my laptop since the file sizes are nice and tiny. But I understand that if I want to get the best audio experience out of my shiny new earphones I would want to use a different format.

As others have said, I hope you realize that this means you need to start over from the source material (i.e. the CD or a lossless encoded copy of the CD) and re-rip these files. There is no way that you can "upconvert" from some low bitrate to a higher bitrate. Sure, you can technically do it, but it will just be wasting space as there is no way to get the quality back once it's gone. And in fact if you care about quality then you should consider lossy encoding to be a one-time one-way operation: never convert from one lossy format to another, always from source/loessless copy to lossy.
posted by Rhomboid at 10:54 PM on January 8, 2007

Above 128kbits/s, ogg has always sounded better than mp3, to my ears, for the same track compressed to similar file sizes.
posted by flabdablet at 3:17 AM on January 9, 2007

I have a pair of ER6i earplugs (the ER6 and ER6i are different models). After comparing the same music in different rips, AAC 128 bit VBR was the best compromise for me. I could easily hear differences between rates and 192 bit was clearly more detailed. These are very detailed 'phones, so higher bitrates are worthwhile if storage isn't at a premium.

On disk-based portable players, lower bit rates give you longer battery life because the device accesses the disk less frequently to maintain the playback stream. Lossless sounds great, but give up on all-day playback if you go that route.
posted by ardgedee at 3:17 AM on January 9, 2007

(Kilobit. It's early, I need more coffee.)
posted by ardgedee at 3:19 AM on January 9, 2007

Raw CD data is 1,411,200 bits per second, and a typical CD is about 650 megs. 320k/sec MP3 is about 1/4 of that. Very, very few people can hear any difference. If you want to trade off close to zero quality, but cut your filesizes by 3/4, use 320k MP3.

But most lossless formats (FLAC, Apple Lossless) compress this RAW data by a half, so the savings are roughly a 1/2, not 3/4.

You've got two different questions. Which format? Which bitrate?

I've noticed that AAC is noticeably better than MP3 at any given bitrate. To my ears, a 128k AAC file sounds about the same as a 192k MP3. On the other hand, MP3s are a bit more interoperable. MP3's are more likely to be supported in some cheapo flash MP3 player or cell phone and it's more likely to be around 10-20-30 years from now.

I would only bother with OGG if you're going to use OGG lossless, since I don't see that format has having a robust future, and with lossless at least you could losslessly re-encode it to another format.

I'm stuck in the Apple sandbox, so I've got my opera and classical music in Apple Lossless. If I were to leave this OS X/iTunes/iPod sandbox, I could losslessly re-encode this stuff. My indie rock/hip-hop is in 192kbps AAC.

As to what bitrate you should choose, well, as others have said, only you could decide how much sound quality you'd want to trade off for file size. I'd recommend at the very least 192kbps VBR.
posted by alidarbac at 6:48 AM on January 9, 2007

All of the format, bitrate, and encoder advice given so far is good. But what you're going to have to realize is that while you're limited by the audio quality of your player and your nice earphones, you're always going to have the final limit of your own ears. Only you can really determine what is "too large" for a file, or degraded quality in your audio.

I personally tend to use lame with a high alt-preset setting. I've purchased albums in FLAC format from bleep and other sources and usually tend to either reencode to Apple Lossless to stream to my stereo, or to a high bitrate mp3 for portable playing. OGG may be a good choice as far as quality per filesize goes for your player, but if you have any plans to trade music with friends or switch devices in the future it might not be optimal.
posted by mikeh at 1:15 PM on January 9, 2007

On the other hand, Ogg Vorbis is free and unencumbered by patents, licencing fees and DRM. Anything that can run Rockbox is always going to support Ogg Vorbis. People have been predicting the demise of Ogg Vorbis since it was first released, and it still hasn't gone away, and it still sounds better than MP3.

Anybody who wants to grab tracks from my own music collection is SOL unless they can use Oggs, and that's no skin off my nose. I feel no inclination at all to choose formats that help the majors continue to rake their cut from the music marketplace.
posted by flabdablet at 8:31 PM on January 9, 2007