Try earlier versions? Or try CBR mode, maybe this will change the result.

Maybe related, or maybe not: https://hydrogenaud.io/index.php/topic,17773.0.html

m4a container written by qaac is different from the ones created by iTunes. fb2k also writes some metadata which is never written by iTunes. Therefore, there *can* be a compatibility issue regarding container. MP4 is an unnecessarily versatile, complex format for storing a single audio track. Some kind of compatibility issues are quite common in poor parser implementations, especially seen in hardware players.

However, since your ipod is able to play at least one track, I guess it's not simply because there's something in the container which iPod cannot handle properly.
There might be an issue in the sync process when files came from outside of iTunes... but I really have no idea.

    Support decoding FLAC in MP4.
    AAC decoder: now recognizes 6.1ch/7.1ch AAC channel config constants (11 and 12) defined in 14496-3:2009/Amd 4:2013
    Concatenating files with no title tag with --concat now creates empty chapter name (formerly file name was used).
    --start now accept negative value. using --start and --delay at the same time is not allowed now. These two options are the same in functionality-wise, except for the reversed sign (For trimming, you use positive value for ---start, and negative value for --delay).
    --adts and --concat doesn't allow concatenating files with varying sample format anymore.
    External dlls are now loaded in lazy way, which means that they are not loaded until needed.
    Increased buffering size for --play to avoid glitches on multi channel files.
    --native-resampler now always use dedicated AudioConverter.
    CAF: enabled 7.1ch rear AAC output.
    AAC in CAF: when chan chunk is not present, get channel layout from kuki chunk.
    Named pipe output is removed. I guess it has been rarely used anyway, but if you happen to want it, use https://github.com/nu774/namedpipe .

Different question from the previously asked in the Opus thread, will the new qaac or refalac support Opus in a CAF container since Apple will start using it? Thanks nu774.

What are the codec constraints of CAF?

(You can see this list by running https://github.com/nu774/cafmux)

This method has a danger of introducing some pops/clicks, but can reduce zeroes at beginning when decoded, and also beginning of the input can be (hopefully) more or less restored (instead of just discarding them).
Any comments?

You can try this by the attached experimental implementation:
[attachment=7286:qaac.zip]

Since then, are those "popclicks" still there with no delay option ?

Quote from: andiandi on 2017-09-20 17:45:10

Since then, are those "popclicks" still there with no delay option ?

Actually, I'm routinely using it for encoding video soundtrack. Don't use it for music.

Nothing has changed regarding --no-delay option.
--no-delay is safe as long as the beginning (50ms or so) of input signal is digitally silent.
Moreover, even when the beginning of input signal is not silent, you won't hear any "glitches" as long as you listen to one file only.
The effect of --no-delay should become apparent only when you encode two or more gapless inputs, and you listen to the gapless transition between songs.