I've recently purchased an ipod nano and wish to listen to DAB grabs from my Pure BUG radio via SD card @ 128kbps MP2, and also some older 198kbps WMA files. Both are CBR.

I'm aware that to transcode from lossy to lossy would lose further but would i lose less if I a transcode to a higher m4a bitrate. i.e. 128kbps MP2 -> 150kbps m4a and 198kbps WMA -> 225kbps m4a.

Or would the loss be the same so I should just transcode at (around) the original bitrate?

I am transcoding using Foobar and neroAacEnc.exe.

Additionally would there be any benefit in transcoding to VBR? (other than a small reduction in file size.)

Thanks for reading...

The problem is that most lossy transcoding involves a bad source - universal bitrate of 128~192k is good for listening but too low for transcoding. So here nothing will save you as 128 mp2 is a horrid quality, old wma not much better. I'd simply transcode to the same bitrate as your other ipod files. Using large target bitrate will give you the worst of everything.

It doesn't help you at all, but the best solution is usually:

a) to get the broadcasts from satellite rather than DAB (as the bitrate is almost always higher, and often (but not always!) the sound quality is higher), and

b) to find a portable player that supports mp2 (can't help you here).


I agree with shadowking - just use whatever settings you use for CD rips. You can't make a silk purse out of a sow's ear!

Cheers,
David.

Thanks for the quick response guys and nice analogy David, much more polite than Peter Kay's "you can't polish a turd" Thanks for the suggestion, I can look at saving a freeview broadcast via my pc's Winfast TV tuner. A new player is not a current £ option.

I had been ripping CD's to 225kbps m4a files but am going to listen to effect of some lower bitrates to gain disk space.

Shadowking, is increasing the bit rate then the same effect as using a large target bit rate? If so is best case option to just maintain the original files bitrate and CBR setting?

I will do some listening tests but am wondering about the mechanics of what is happening to the original files.

Cheers.

Why don't you make a second copy of one of your MP2 files as a test and simply change the file extension to MP3 (and possibly indicate the fact by using filename_MP2.MP3 so you can tell it's really an MP2 that you changed for compatibility reasons). Windows will ask for confirmation and warn you, but if you keep the original, you won't break anything.

If Windows is hiding filename extensions (which it does by default, and I always turn off), you can show them by Tools/Folder Options.../View/Advanced Settings/ and unchecking the "Hide extensions for known file types". You could simply apply that View setting to your DABrip folder if you want but otherwise leave your PC as you like it.

That method has worked for my MP3 car stereo which refuses to even look at files with the MP2 extension (much as iPods won't look at MP4 files until you rename to M4A). Fortunately, too, the files are very close to 89dB SPL loudness so I don't need to care about applying ReplayGain to match my other music.

I understand that a compliant MP3 decoder should also handle layers 1 (very rare) and 2 (i.e. MP2) as well as 3 (i.e. MP3). I should add that my tested files were not sourced from DAB, but were encodings of mine from the 1990s when I had a very slow PC. DAB usually inteleaves text info (e.g. song name, programme & presenter name, sports score, traffic) into the bitstream but this should be outside the frame boundaries so shouldn't adversely affect a compliant decoder.

I don't know of any hardware or software decoders where this renaming method hasn't worked, though my experience is naturally limited to the small number of devices I've tried it on.

Just be aware that tools like mp3gain and mp3directcut won't be able to apply volume changes and might choke on MP2's in disguise.

Renaming avoids transcoding for MP2, though you have no choice with WMA.

Then again, if you want lower bitrate, AAC (or Ogg Vorbis) if supported by your device can do pretty well at much lower bitrates than MP2 and MP3 (e.g. 64-96 kbps).

With an iPod Nano, installing the Rockbox firmware might be an option that removes the need to transcode or rename entirely and gives you lovely features like ReplayGain.

Thanks for info Dynamic (Mr Dastardly???)

I've tried renaming to mp3 but "audio format is not supported by the ipod".
It seems that with renamed files itunes (and foobar) still recognise them as mpeg layer 2.
The windows filename is not the same as name/title in itunes/foobar.

Rockbox is another good suggestion but my 2nd gen nano is not supported.

Thanks again for you considered response, I think i'll continue listening to further reduced bitrates because so far 125kbps aac (m4a) on my headphones and car stereo sound spot-on.

Not DickDastardly, but DickDarlington. Equally fictional, however.

Anyhow, thanks for the first info I've seen on a player where this doesn't work - and it's a serious mass-market player too. If it's indeed true that it's a requirement of a compliant MPEG decoder to handle layer 2, then it doesn't surprise me to find the Apple is the exception, though I wouldn't complain bitterly given that this is a rare situation and it's a decent player in most respects (though again, it's non-compliant by not accepting .mp4 filenames).

This is probably just iTunes assuming that the ipod can't play the file, to be really certain, replace an existing MP3 on the ipod (the files are in \iPod_Control\Music\randomly named folders). You can tell what the original MP3 is by loading it into foobar/media player/something which should display it's true title, then replace that file with the MP2 file. Try playing the track on your ipod. If it works, you could perhaps appeal to musicmusic to add the ability to send MP2 files without transcoding to foo_dop.

Close then (i'm in Manchester), there's a fella from the UK on my nintendo wii called DickyD, thought it might be you.

The lack of compliance thing is acceptable to me because i'm finding it a great product, even good enough to put up with itunes! tho not for long if i can get happy with foo dop.

Anyway thanks again.

Thanks for the suggestion but no joy there i'm afraid.
I tried several methods with my renamed mp2 file but each did not play.
Replaced ABCD.mp3 with ABCD.mp3
Replaced EFGH.m4a with EFGH.mp3
Replaced IJKL.m4a with IJKL.mp2
Replaced MNOP.mp3 with MNOP.mp2

I will check out foo_dop though, cheers.