nevadanevada wrote:
I've recently come to conclude that if I try to add WAV files with the same sample size, sample rate and bit rate, respectively, to my iPod nano (installed software is up to date) then iTunes displays an error message saying "cannot be played on this iPod".
Do you happen to be aware if this is a limitation common to all iPods?
Each iPod model has its own limitations on the audio formats it can handle. You can find the specific limitations for all but the WAV format for most models at
http://support.apple.com/specs/#ipod. In general, the highest bit rate for the listed formats is a good indicator of WAV format limitations.
Also consider that it is essentially pointless to use higher bit rates & sample sizes than the onboard digital to analog converter of any playback device can handle -- even if the device does internal "downsampling" before conversion, it is highly unlikely that the analog audio output circuitry has been designed with the precision to make any audible difference in the result.
In fact, at different times different iPod models have been considered to have the best "audiophile" sound quality even at lower bit rates than the maximum they can handle because of the specific analog converter & output circuitry they use. Surprisingly, when the original iPod Shuffle was introduced it was considered by many to have the best audiophile sound of any then current iPod.
Similarly, different playback devices vary in how accurately they handle different compression formats, especially the various VBR (variable bit rate) ones. Since this can vary depending on the complexity of musical content, there really is no one format guaranteed to produce the most pristine output, so some experimentation is always a good idea when choosing a format for transfer from your music library to your other playback devices.
Conventional wisdom has been to store the original in the library in its original, uncompressed format (assuming that is available) or an equivalent lossless format & convert that as appropriate for the external playback device. But even that may change in the foreseeable future because of some remarkable advances in methods of recovering what lossy compression formats discard. So far it has only been used with images (pictures & video) but it does what was previously considered impossible: reconstruct missing detail seemingly out of thin air. It is hard to explain how it works but it based on the discovery that if you let a computer alglorhrimically try enough guesses about what the missing details might be, for real world content the simplest guess is invariably the correct one. What "enough" & "simplest" means in this context is the tricky part, involving a highly abstracted mathematical analysis with no everyday language equivalents, but researchers have demonstrated that for a huge number of images, including ones so highly compressed they are almost unusable, the technique can reconstruct an exact or almost exact version of the original.
This literally could change everything we think we know about lossy vs. lossless compression but for now the conventional wisdom offers the best approach.
