Opinions on Bitrates

I know this belongs in Digital Formats, but I ponder the same thing as you, sinster. I encoded all my cds into 192 kbps CBR mp3. I got a 30gb and I have still about 14 gb of space left. With all this space, I have wondered should I have encoded it at 256 or 320 (from my research, I hear that LAME encoding at 256 is better than 320, go figure).

Moral of the story is, I guess be happy with what you got, for at a certain point (which I think is 192 kbps CBR), it is pointless to be trying to get better sound quality because thats how compression is. If you wanted exact CD quality stuff to carry around, that's what CD cases are for. The file size of a .wav going from 55 mb to 4 mb is already incredible; something has to give in between from ripping to playing. Just be happy with what you got, but have the best you can get.

If I had a choice between encoding at 128 or 192, I'd pick 192 for the sheer fact that I can hear the difference. If you can, I don't know. In most cases, like lets say your in the car playing the iPod and someone else is with you, they will most likely not care if its 128 or 192. You might, but for someone else its not that big of a deal.

If you haven't check out 320 or 256. I know people say that its overkill or stupid for encoding that high, but I can hear a difference in the low end department with higher bitrates. Maybe its in my head, maybe its not. You must differentiate what is real to you or not. Oh man, maybe I shouldn't have watched that Matrix movie. :D

I've found that there is a noticeable difference between
128 and 160Kbps...The higher you go the less it will affect the quality...Anything above 192Kbps is pretty much not discernable quality-wise to most people's ears. If you can't fit the collection at 192Kbps why not try 160Kbps...It's a nice compromise that gives noticeable quality improvement from 128K...
I've personally never cared for VBR but have nothing really against using it either.
Regarding encoders...You'll see alot of people recommending EAC/LAME combination. EAC is indeed a good ripper (A little on the slow side) but gives excellent results...I personally do not like LAME...I've compared the results of encoding the same file using LAME/Xing/Fraunhofer...LAME always comes out the worst at the same bitrate compared to Xing and Fraunhofer...However it's FREE and that's why people ususally recommend it...

motox22a (or anyone),

What is the disadvantage of VBR? I figured 192 VBR (alt-preset std) would be indistinguishable from 192 CBR, using less HD space, and that's why I ripped everything there. Not disagreeing with you, just trying to understand why anyone would ever use CBR unless you had way more space than music (320 CBR). I suspect this is a pretty esoteric discussion isn't it (I'll learn)...

Like I said I've got nothing against VBR and I do understand the reasons and advantages for it...However...For MYSELF...I use my MP3 Files on various MP3 Players and devices besides the IPOD and have found that VBR sometimes has side effects on things like time counters and VBR was not initially supported universally on all players (Legacy players) so to have universal MP3s that I can use on any MP3 Player I found it was better to have CBRs rather than have to convert for a particular device...That's all...

sinister (or anyone else),
any reason why you haven't tried AAC?

Originally posted by tntracy
Right now, my personal preference are these settings for encoding in iTunes:

MP3: 192 Kbps, VBR, normal stereo, using iTunes' "highest" quality level for VBR

AAC: 160 Kbps.

I used to be quite happy with 160 Kbps VBR MP3s until I got some very good, detailed earphones which prompted me to re-encode to 192.

BTW, there are two iPodlounge FAQs on this subject - here (http://www.ipodlounge.com/faqs_more.php?id=111_0_10_0_C) and here (http://www.ipodlounge.com/faqs_more.php?id=289_0_10_0_C) - if any one is interested.

Tom

What earphones are those?
When do you use AAC and when do you use MP3?
If you have good quality earphones, maybe it would be worth encoding AAC with QuictTime Pro to get the High Quality setting (it's set to low in iTunes).

Originally posted by tntracy
Etymotic ER-4Ps.

So, I am intrigued by your comment concerning encoding from QuickTime Pro. How does that work? Is there a plug-in or something for iTunes so that you are still ripping and encoding from within iTunes, or do you rip & encode it QuickTime Pro separately, then add the AAC files to your iTunes library?



Those earphones seem to have excellent press. I bought a pair of sennheiser PX200 over the ear headphones for portables which I use in the office and at home - much more comfortable than Apple's ones, fairly good insulation of environmental sound and a nice clear sound. Plus they fold up neatly once you're finished with them. I wouldn't wear them outside though, as I would feel too self-conscious.

Just one question on the ER-4Ps - is it easy to keep them... eh... clean ? :)

When you encode in Quick Time Pro, there are 3 settings for AAC - good, better, and best. Based on the time it takes to encode an AAC, and from confirmation from an Apple source (which I found on a discussion thread at the Apple site), iTunes is indeed set to encode using "good". I think that with your quality headphones you should be quickly able to tell the difference (the guy at recordstorereview.com certainly could).

128K AAC sounds fine to me but I'm encoding to high quality as it seems silly not to use the highest quality setting. I have Quick Time Pro so I use a cool shareware called MakeMineMPEG4 (http://www.malcolmadams.com/itunes/itinfo/makeminempeg4.shtml) - basically an AppleScript that works with iTunes and QuickTime Pro fairly seamlessly. Before that I tried Aacelerator (for which you also need Quick Time Pro) but I hated that - MakeMineMPEG4 is way better (and actually cheaper). You can try both as a demo before buying.

If you don't have QT Pro, you can try using Aachoo (haven't got the link) which, unlike the other two, isn't an Applescript and works directly with the Quick Time encoder (no need for Quick Time Pro). Apparently (according to their web site anyway), it encodes at high quality setting. It's horrendously slow though but you can give it a whizz as a shareware.

If you do, let us know what you think,

hth,

pingin

Well I've been researching this topic for a while... I used to encode all my stuff around 192 VBR in iTunes. I'm just gonna throw out some of my opinions, hopefully someone finds them useful.

1. Compressing your music makes it sound worse. If you don't want to listen to an inferior version of your music, don't rip it.

2. The point of MP3s and the other compression schemes is to make your music smaller so you can more easily store it on a hard drive. iPods don't come in Terrabyte sizes.

3. You don't keep both an uncompressed and a compressed version of your music on your iPod. All the music has to be compressed. The point: there is no A/B-ing between the ripped and original version. When most people hear their MP3/Ogg Vorbis/ACC/WMA/RMA file it sounds like their music. If you then compare it to the original, sure it sounds ####tier. But _by_itself_ the stuff sounds good. Pristine? No. Good enuff, considering you have access to thousands of songs? Definitely.

4. There is always a trade-off between sound quality and file size.

5. Between ripping, getting artwork, and cleaning-up tags, converting a large cd collection is not an easily done job. Anything that makes it simpler is valuable.

6. The size of your cd collection vs. the size of your iPod should be taken into account. If you have only 100 cds and a 30GB iPod, go nuts! But if you have 200 cds and a 5GB iPod, it'd behoove you to consider lower bitrates.

Those are all well known, obvious points, but they seem to get lost in all the arguing about which codec/bitrate/ripper is better. There are so many audiophiles writing about how they test these files by playing them through their super-duper hi-end systems and they sound terrible. That may be an entirely accurate assessment, but it is not germane to the discussion. Using 256-bit encoding rates defeats the primary purpose of most people ripping their music.

I'm not going to go on and on. Here's my summary: I have a 15GB iPod. I probably have around 270 CDs. I like the idea of having the whole collection in my pocket. I used to rip MP3s around 160-192. If ACC at 128 is equivalent to 160 MP3, but gives significantly smaller file sizes, why wouldn't an iPod owner go for it? Does the music sound "pristine"? Uhh... listening to it right now, by itself, it sounds pretty #### good. I still wasn't able to get _everything_ on the iPod, mostly because I have a lot of downloaded MP3s that are copies of things I own on cassette, and therefore can't make it to ACC to benefit from the small size (well, at least I'm not willing to convert them and lose more quality). But out of a total collection of 3653 songs, 3373 have made it on to the iPod. Not bad at all. And like I said, they sound great (not compared to the original, but then again they're all in my pocket accessible instantly, not in a UHaul truck I need to drive everywhere)!

128 ACC is teh l33t codec. iTunes, similiarly, is friggin' awesome. Is the ACC encoding quality suspect? Dunno. Don't care. I got album art, and all my tags and even EQ presets in (I re-ripped my entire collection over the last week). Granted, I've been neglecting everything else for several days...

Just my 2 cents. I think most people will be psyched to actually get the advertised capacity of the new iPods. And the real world benefits to the ITunes/iPod/iTMS solution are... real. Would LAME do a better job? Define better. That's all I wanted to say. Well, that and thank you to everyone who's been contributing their own opinions about this. Trying to research such a subjective topic as audio quality now seems kinda pointless to me after doing it for several days, but everyone's reviews and suggestions were appreciated nonetheless.

Audio CDs are said to be encoded at 186 br ( around there )

hence 192 @ joint-stereo would be the closest resemblance to the original.

I've used 192 for ... oh almost 1 1/2 years now, and its fine for me. Until recently i did some research on the alt-presets and found --alt-preset standard to be exceptional.

imo, --alt-preset standard is the best br for non-audiophile encoding using the lame 3.9.0.2 codec and eac.

note: my reference to the 186 br is what i've found on websites, although i cant completely prove or stand behind this statement.

To start to understand why Apple choose AAC over the many other available formats on the market I will need to explain who created it, when it was created and why it the sounds quality is better than the MP3 File Format.

AAC was created by the MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony, and Nokia, companies that have also been involved in the development of audio codec?s such AC3 (also known as Dolby Digital). MP3 was also created by the MPEG Group but I believe that the MP3?s time is now up from once being the most popular codec for storing and transferring music and that AAC?s time has just started.

The MP3 file codec was created over 10 years ago, I was never a big fan of MP3?s sound quality one of the reasons that this may have been because was that it employed a "lossy" compression system which removes some data leading to the loss frequencies, judged to be essentially inaudible. Listeners believed to think that MP3 managed to deliver near-CD sound quality in a file that's only about a tenth or twelfth the size of a corresponding uncompressed WAV file, the size maybe true but I strongly disagree that it was near CD quality and would rather listen to tape. When creating an MP3 file, various amounts of compression can be selected, depending on the desired file size and sound quality a lot of the times I found these files to be over compressed resulting in a thin sound with loss off bass and definition within certain frequencies.

The original MP3 codec in now being replaced with MP3 Pro, which I have just recently found out. Its combined with MPEG4 which also includes AAC allowing small, low-bit rate files to contain much more high-frequency detail than standard MP3 files encoded at similar low bit rates.) The high-frequency portion of the audio signal is handled by an advanced and extremely efficient coding process known as Spectral Band Replication (SBR), while the rest of the signal is encoded using the same process as in regular MP3. This enables older MP3 "player" software applications to play files encoded in MP3. I am not going to do in to the depths of MP3Pro as it contains AAC, but I would say that they are each other?s competition.

Due to the popularity and development of the internet over the last few years, most people downloading music (via MP3 format), have relised that the quality compared to newer formats such as MPEG-4, 3GPP, and 3GPP2 is not nearly as good as it should be. This is due to the fact that the MP3 is over a decade old; within in this time lots advances in audio coding and compression have been achieved. AAC combines many of these advances; we can now use lower data rates whilst gaining a higher quality output, this has opened a doorway to the future of how we listen to music. The first encounter of AAC even for those of us that don?t have an I-pod will be via digital broadcasting, mobile multimedia, and Internet services.

The AAC codec builds upon new, state-of-the art signal processing technology from Dolby Laboratories and brings true variable bit rate (VBR) audio encoding. Bit rates are a measure of how many bits describe each sound in an audio file. A low bit rate means lower quality and a smaller file size, while a high bit rate means better quality and larger files. The standard bit rate is 128 kbps. True variable bit rate is a type of compression wherein certain audio sections are encoded at different bit rates so that complex sounds are encoded at a higher rate while simple sounds are encoded at a lower rate, as opposed to Standard bit rate encoding where the type of compression wherein an entire audio file is encoded at the same bit rate. This means you get the best sound possible for a certain amount of disk space. There is a disadvantage of this which is that certain players occasionally have problems decoding VBR audio files.


Getting Technical

Although I have been only referring to AAC as the one and only file type, advances have been made and will going as I write this essay. AAC can really stand for two things: either MPEG-2 Advanced Audio Coding or MPEG-4 Advanced Audio Coding and as its full name suggests, it is either an MPEG-2 or MPEG-4-based audio format.

The MPEG-2 version of the format is also often called as MPEG-2 NBC as in Non-backwards compatible, but the correct name that should be used, is the AAC. The NBC name comes from the fact that unlike older MPEG audio encoding methods, it is not backwards compatible (for example, MP3 is backwards compatible to MP2) to older MPEG audio formats.

When coming to music we are mainly concerned with MPEG-4 AAC as it produces better quality and smaller files than MPEG-2 AAC. This again can be broken to MPEG-4 AAC Low Complexity (LC) and MPEG-4 Spectral Band Replication (SBR) to MPEG-4/HE-AAC.

HE AAC stands for High Efficiency Advanced Audio Coding, it was created from a combination of MPEG-4 AAC (LC) and MPEG-4 (SBR). Quoted and proven from MPEG it can deliver ?coding gains of more than 40 percent compared to MPEG-4 AAC LC.? It also has an ultra low bit rate coding, as low as 32 Kb/s Stereo (45:1 compression!) HE AAC is able to achieve superior audio quality, without losing treble sound or collapsing of the stereo image. According to the formal listening tests done by leading broadcast unions, HE AAC clearly outperforms competition at 48 and 64 Kb/s.

Advantades of AAC over MP3

Improved compression provides higher-quality results with smaller file sizes this could be put to the test be listening to of the same songs with the same file size via MP3 and AAC and hearing the the Aac file was defiantly a lot better in quality..

Support for multichannel audio, providing up to 48 full frequency channels

Higher resolution audio, yielding sampling rates up to 96 kHz rather then the MP3 which only goes to 48 kHz.

Improved decoding efficiency, requiring less processing power for decode

Sorry if this is covered somewhere else. I've been automatically using the mp3 format (out of reflex I guess) and after reading this conversation I'd like to switch to the aac format, mostly to save file space (my 15G ipod is pretty full). Is it worth it to convert a 192 CBR .mp3 file to a 160 .aac file? Or would audio quality issues from the conversion make it necessary to re-rip the original CD to aac instead? I'd rather convert than re-rip, but if conversion means a significant loss of existing audio quality, then I'll have to re-rip.

Originally posted by Eddie '92
I was thinking about writing a really detailed reply to this with loads of technical babble but the fact is I'm listening to a 128K MP3 right now and it sounds great, and it sounds great on my iPod with Sony Fontopia earbuds. Dont you guys get it, you are bored with your music so you put it down to quality! For God's sake enjoy your music as it and will you all get a life!

Eddie '92

Aahhhh! Thank you. Someone finally agrees with me and realises thats 128k is the best bitrate. Now honestly if you had a 4gb hard drive (PC NOT iPod) and wanted as many songs as possible you would go with lower bit rates just for more songs, and woudlnt know any difference in quality.