XRECODE

On tracks with seamless playing, converting from WAV to M4A results in a 20ms added silence at the beginning and at the end of the track, as shown in these screenshots:

end of track

WAV


M4A

start of next track

WAV


M4A

Tried replicating the issue converting the same files to other formats and conversion was fine with those, the issue was only present with M4A conversion. Some other seamless playing tracks I've converted don't present this issue, as this is the first time I've noticed this issue on any WAV to M4A conversion, so I'm unsure as to what specifically is making this happen with these particular tracks, only on M4A.

I tried with qaac and nero and can see that silence added, but that might be something to do with the ITUNSMPB tag saved into file, which is used for the gapless playback. Anyway, when I tried to listen to the encoded (gapless) tracks, they were perfectly fine.
And just to double check, I converted the same files manually from the command line, using qaac and nero, and got the same result.

In my case the small gap is audible on foobar2000, that's how I noticed this issue first. Though it is true that these were manually cut from a longer WAV file, never bothered to actually tag them as gapless, that my be the issue. I'll check again and report.

Haven't managed to find where to set that tag, but I tried converting it again, and while the silence was there, it did indeed play correctly gapless on foobar2000 this time, must have been an issue with the player, then. Whatever it was, it's working now, so all's well ends well I suppose.