Have I lost my mind (bit rates)!?

[buchananmb]

I am steps away from deleting my entire library because of concerns about various bit rates and sound qualities. I could use some feedback in terms of best next steps with my collection. I understand that 128 kbps mp3's are perfectly good for most listening, but if I have space and time should I make some changes?

2,500 tracks that were ripped from store-bought cd's into 128 kbps mp3 (using musicmatch jukebox with its default ripping settings);
500 tracks from iTunes (128 kbps AAC) that have been converted to 192 kbps mp3 by iTunes (middle step intentionally left out);
1,500 tracks from various sources that are 192 or above and mostly variable bit rate (LAME).

My first question is if I just re-rip the 2,500 cd's since I still have the cd's? If so, what should I use and what bitrate, etc. (320 vbr?)? I am an mp3 person, but am open if an alternate format works across various music devices (iPod, Roku soundbridge, iTunes).

Second question, what about the converted mp4's? Did they lose quality during the second lossy compression? Can they be improved or just leave them as is?

[xoas]

Re: Have I lost my mind (bit rates)!?

My first question is if I just re-rip the 2,500 cd's since I still have the cd's? If so, what should I use and what bitrate, etc. (320 vbr?)? I am an mp3 person, but am open if an alternate format works across various music devices (iPod, Roku soundbridge, iTunes).

There would be 2 reasons for at best for re-ripping. First is because you are dissatisfied with the quality of your files. Granted, I prefer to rip to higher bitrates but if you are satisfied with what you have got, then this isn't a factor.

The other reason for re-ripping would be if you wanted higher quality copies for back-up purposes, especially if you do not anticipate keeping all these cd's. If you are keeping all the cd's they are their own back-up unless you use them a lot also.Some people prefer to archive original cd's to a lossless format such as Monkeys or Flac and to keep other copies for everyday use. But you might equally be satisfied with higher bit-rate lossy versions.

These are the only two situations I can think of where you would want to re-rip.

Should you decide to re-rip, I am not familiar with Roku Soundbridge so I don't know what it supports. "Expert" opinion would tend to recommend either one of the lossless formats (although these will take up quite a bit more space than your mp3 files), or Musepack (especialy at 160 kbs or higher), Ogg or AAC/m4a over mp3. However, mp3 is by easily the most portable format (wma being the second most supported format-and for space saving you might find wma able to provide similar quality copies to your 128 kbs mp3s at around 96 kbs). So I see no reason why you should be switching from mp3 unless you have a need for re-rip these tracks anyway.

Second question, what about the converted mp4's? Did they lose quality during the second lossy compression? Can they be improved or just leave them as is?

Yes they lost some quality during the second lossy compression. However, they did not necessarily lose enough quality for you to notice the difference. You can test this by taking some 128 kbs AAC files convert them to 192 kbs mp3 and listening to the two sets of tracks to see if you notice a difference. If not, you definitely do not have a problem. As far as trying to improve the mp3 files, that is not an option. There is nothing you can do that will improve them. If you find they are undesirable your ooptions are to go back to the 128 kbs. AAC files (if you still have them) or re-ripping (if you still have the source material).

Hope this helps.
Best wishes,
Bill

[buchananmb]

Re: Have I lost my mind (bit rates)!?

Bill, thanks again for the feedback. Very helpful. Given I have an ipod, it seems my best (only?) lossy choices are .aac or .mp3. Does .aac actually produce a higher sound quality than .mp3 or does it just produce an equal quality at a lower bit rate? I had planned to go with .mp3/alt preset insane (increasing file size on average by about 2.5 times?). What would be an equivalent .aac setting? I am a bit leery of going with .aac since it seems tied to the ipod at this point (or am I wrong on this?).

(I can keep my cd's as an archive since I don't use them and don't have the storage lossless would require.)

[xoas]

Re: Have I lost my mind (bit rates)!?

Does .aac actually produce a higher sound quality than .mp3

Yes. At the same bitrates AAC should give better performance than mp3. This being said, the operational question should be at particular bitrates, do you notice a difference between the 2?

or does it just produce an equal quality at a lower bit rate?

Well the answer here is also Yes. You can compensate for the difference in quality between AAC and mp3 by encoding mp3 at a higher bitrate than AAC.
As you get to higher and higher bitrates, however, it is likely that you will start losing the ability to discern differences in bitrate settings. With mp3, I have found that I do not recognize any improvement above a bitrate of around 240 (or alt-preset extreme).
Likewise, once you get aac bitrates and mp3 bitrates sufficiently high, you are likely to find differences between are no longer distinguishable.

Now that is my experience. As I have stated previously and elsewhere, any given listener's response to music is the result of many factors including the equipment you use for recording and playback, your own listening ability, the environements in which you do your listening, your listening tastes, and so forth. Practical aspects of the convertability and portability of particular formats and of the amount of storage space available and the features of a portable player (in terms of the formats it will support and the amount of storage capacity it has) also make a difference. There are some listeners who might note a qualitative difference between a lossless file and, say an mp3 file encoded at alt-preset insane. There are many listeners for whom far lower bitrates do just as well. And, as I have stated before, I have mp3 files originally encoded at 128 kbs that I enjoy greatly even though I wouold not personally encode those files to such a bitrate myself.

I think certainly for your iTunes downloads you would be best off sticking to AAC. Converting those files to mp3 at 192 kbs. is probably sufficient to minimize quality loss except for the unavoidable loss you encounter whenever you convert audio from one source (here an already lossy source) to another. For music you rip yourself I think that is up to you. Your iPod gives you a lot of space. It will support mp3 and AAC. Your computer will support both. If your other player supports mp3 but not aac, then ripping to mp3 makes sense (although Spoon has a multi-format codec available in beta that allows you to convert the same file to two different formats and/or settings at once, which minimizes the hassle of dual conversions considerably). AAC is generally a superior codec to mp3 but it is not as widely supported. Whether it will be in the future is anyone's guess.

Since you know you are pretty much going to work with mp3 and/or AAC, I strongly encourage you to rip a number of sample files to both AAC and to mp3 at a variety of settings (say 96 kbs, 128 kbs, 160, kbs, 192 kbs, 240 kbs and 320 kbs). Granted the quality settings in AAC and the alt-presets make this somewhat of a guessing game but you get the idea. Find out where your musical "sweet spot" is. Then try to do your conversions there.

So those are my thoughts and my recommendations.
Hoope they help.

Best wishes,
Bill

[GSV3MiaC]

Re: Have I lost my mind (bit rates)!?

Just to add (to the already excellent advice) that if you want to do proper, unbiassed, listening tests then WINABX (free!) lets you compare two different sound file encodings (having turned them both back into .wav) on a PC. Doesn't help you do it on an MP3 player, or in the car, but at least on the PC you can answer 'can I tell the difference or not'. Many people can't.

Of course even if you can tell the difference you still have to answer the second question 'do I care' .. or 'do I care ENOUGH to use twice the disk space'. 8>.

[buchananmb]

Re: Have I lost my mind (bit rates)!?

I can tell that I want to use m4a because I sense it's more advanced and would allow a given quality at a smaller file size; the only negative being compatibility--even though I am an ipod user. The second place thought is use mp3 at a higher bit rate to close the gap because storage is so cheap and drives are getting bigger and bigger. Thanks for the tip about WINABX!

[xoas]

Re: Have I lost my mind (bit rates)!?

if you want to do proper, unbiassed, listening tests then WINABX (free!) lets you compare two different sound file encodings (having turned them both back into .wav) on a PC.

-GSV3MiaC

Great tip. There is a link for WinABX (for those who might be intersted) here:

http://www.kikeg.arrakis.es/winabx/

Best wishes,
Bill

[Tomb]

Re: Have I lost my mind (bit rates)!?

There was a multi format test at 128 k/bits carried out last year by the Hydrogen Audio community: The results were:

As you can see the I-tunes AAC codec (the best one at present) is not that far ahead of Lame mp3 at all.

Therefore I say follow GSV3MiaC's advice, download winabx and decide which format is best for you. And as Xoas says can you notice a difference?

More on the test mentioned here and here.

[buchananmb]

Re: Have I lost my mind (bit rates)!?

My wife is hoping I get to some conclusion soon!

I did some testing last night and this morning (alt preset extreme 221-241 and m4a 224-256) and I am suprised that in each case I could identify which track was mp3 and which was m4a. I used two tracks from cd's and encoded both to mp3 and m4a; using an m4a bit rate that was similar to what the mp3 came out to. I used abx as well as simple random shuffle of the unlabelled test tracks in itunes and rhapsody. Headphones and pc speakers. The best way I can put it is the m4a tracks have a richness/depth that the mp3's don't (at similar bit rate) and I could spot it.

I think it just confirms my sense that I'll have to use higher bit rates if I want to go with mp3 to maintain player flexibility. Please let me know if you see something in my process that looks funny to you.

[xoas]

Re: Have I lost my mind (bit rates)!?

Please let me know if you see something in my process that looks funny to you.

Well the wife is right to worry.
Basically, I suspect you are on the right track although 2 tracks is a small sample. And the next question would be whether mp3 at alt-preset insane would sound as good as your extreme m4a.

For a listing of requirements for a properly designed listening test, you might want to check this list here: http://www.pcabx.com/#ten_req
I am sure you can find your own real or potential limitations (of your listening test protocol only!) listed therein.

But do try to take heed of your wife's warning. My own experience was that the listening tests I did started to get seriously in the way of enjoying music, not to mention my family life. They were a good experience but one of the lessons I took away from the experience was the importance of systematically doing a little sample listening at a time rather than to try to listen to a great deal at once. This, of course, amplifies the importance of being systematic.

BTW, I note that your SoundBridge does seem to support AAC, so that AAC would seem to meet your present needs as much as mp3 would.

Best wishes,
Bill

[buchananmb]

Re: Have I lost my mind (bit rates)!?

I agree that it's time to refocus on enjoyment! One last question that may fit in a new post? Is there a front-runner for encoding to aac similar to LAME in the mp3 world.

[GSV3MiaC]

Re: Have I lost my mind (bit rates)!?

I did some testing last night and this morning (alt preset extreme 221-241 and m4a 224-256) and I am suprised that in each case I could identify which track was mp3 and which was m4a.

I'm not - MP3 (even LAME, which is the best encoder) is 'well old' technology now, and gets eaten alive in my listening tests by any of the more modern (especially the VBR) encoders - WMA 2 pass VBR, or .OGG Vorbis (event he released version). I haven't tried m4a, but if it =didn't= beat MP3 it's be a pretty poor show.

Of course I'm usually well down the bitrate curve from where you were testing, but I suspect that MP3 just has an upper limit on goodness, and chucking more bits at it doesn't help all that much. 8>.

[xoas]

Re: Have I lost my mind (bit rates)!?

Is there a front-runner for encoding to aac similar to LAME in the mp3 world.

Well there are a variety of options for encoding to AAC almost all of them within an mp4/m4a framework.

If you missed it, there is a listening test of various AAC codecs (at 128 kbs) which Spoon has posted at the mp4/AAC codec site here:

http://www.rjamorim.com/test/aac128v2/results.html

If you use the search function for this forum you might be able to find some other useful information by looking at posts from Hans Jurgen.

Best wishes,
Bill

[buchananmb]

Re: Have I lost my mind (bit rates)!?

Thanks for the link to that result. I didn't realize iTunes was regarded so well as an (aac) encoder. It looks like that test is from 18 months ago and I wonder if there's a more current result? I've also read that there may be an advantage to quicktime pro in terms of going from better to best.

[LtData]

Re: Have I lost my mind (bit rates)!?

The best free AAC encoder is normally considered to be FAAC. It is the main m4a/aac codec in codec cental: http://www.dbpoweramp.com/codec-central-mp4.htm