mp3 reencoding

[bigcat]

Hi people,
I've got 4.5 Gb of different music encoded by someone (not me) to 256 kbps mp3 (possibly CBR). I don't know if LAME was used or not.
What i do know is that i need do shrink this music library at least to 2 Gb (or less) without noticeable loss of quality. All the variants i have are mp3 (LAME) and mp4/aac/aac+ any profile (NeroAacEnc and the one from WinAmp plugin that encodes to aac+). That is to put it on iPod nano 2G which supports it all. I'd like to know if it's possible to shrink that music this way with no noticeable loss. Time, memory and resources are not important for me:)

And one more question. I encoded file using enhAacPlusEnc.exe (enchanced aac plus used with CLI plugin for dbPowerAmp) at 64 kbps and got an .mp4 file. Winamp, QuickTime and iTunes recognize its sample rate as 22 kHz, but the original file was 44 kHz! I convert this file to WAV and get 44 kHz with almost the same quality (indistinguishable from original) again. I converted that .mp4 file to .aac using dbPowerAmp plugin for changing aac containers (no reencoding had been done) and got the file with the same bitrate and size, but WinAmp and QT recognized it as 44 kHz. The problem is that iTunes, which i need to upload music to iPod, doesn't accept .aac file. I renamed file to .m4a and although iTunes accepted it, it didn't appear in the list of music, and so it won't be uploaded. What appears to be the problem? Is it compression that iTunes doesn't understand or is it wrong file format?

[setarip_old]

Hi!I've got 4.5 Gb of different music encoded by someone (not me) to 256 kbps mp3 (possibly CBR). I don't know if LAME was used or not.You might want to RE-read the rules of the forum (#6, in particular), as wll as the "ANNOUNCEMENT" at the top of the "Newbies" sub-forum...

[bigcat]

Hi!You might want to RE-read the rules of the forum (#6, in particular), as wll as the "ANNOUNCEMENT" at the top of the "Newbies" sub-forum...

You didn't tell me exactly what i did wrong. That's a music i own (i purchased it in mp3 format already) and i need to shrink it to upload to ipod.

[bigcat]

Hi!You might want to RE-read the rules of the forum (#6, in particular), as wll as the "ANNOUNCEMENT" at the top of the "Newbies" sub-forum...

You didn't tell me exactly what i did wrong. Yow woldn't deny that if that music is in mp3 format, then SOMEONE was encoding it, maybe the same studio that recorded it. That's a music i own (i PURCHASED it in mp3 format already) and i need to shrink it to upload to ipod.
About second part - sorry, i guess even iPod 5G doesn't support aac+.

[Sharktooth]

AFAIK iPod supports LC-AAC only. However that's not a problem since you want to mantain the audio quality. 128kbits stereo LC-AAC is very high quality, so you wont loose any noticeable sound detail. 96kbits is good too (about the same as a 128kbits mp3).
if you want a good quality dont go below 96 though.

[foxyshadis]

AFAIK iPod supports LC-AAC only. However that's not a problem since you want to mantain the audio quality. 128kbits stereo LC-AAC is very high quality, so you wont loose any noticeable sound detail. 96kbits is good too (about the same as a 128kbits mp3).
if you want a good quality dont go below 96 though.

A lot of people would dispute "very high", but in comparison to the average 128 mp3 on a website, it probably is. Current Lame mp3 is nearly as efficient as lc-aac encoders though, shocked me when I tested those claims. (Although my hearing is no audiophile's.)

As for showing he-aac as 22khz, that's an artifact of lousy information panels caused by the lousy way that it's stored in mp4 (no HE flag to signal a sampling rate doubling). ps, you can't just rename .aac to .mp4 or .m4a, you have to mux it, but it's better to convert directly to it. (Although an .m4a is technically supposed to be equivalent to .aac, a raw aac stream, Apple has redefined standards instead of bothering to pick a new extension, and now .m4a is aac muxed in mp4.)

You didn't tell me exactly what i did wrong. Yow woldn't deny that if that music is in mp3 format, then SOMEONE was encoding it, maybe the same studio that recorded it. That's a music i own (i PURCHASED it in mp3 format already) and i need to shrink it to upload to ipod.
Yes, well, read the announcement - the onus is on you, not the forum, to identify the legitimacy of questionable content, because of the tenuous legal position of the forum.

[bigcat]

Thanx 4 help. All you said here is right.