OK, I think this is what the problem is with piping the output of an mp4a stream. Please correct me if I am wrong because obviously I am not as knowledgeable.
If I save an mp4a stream as a file and then try to play/decode/stream everything works fine
.
If I try to save it as a nameless pipe, it still probably works, although I cannot replay/decode it on the fly.
If I try to save it as a named pipe, vlc refuses to do so, the named pipe remains at zero bytes in size. This might be a format/codec issue that might be incompatible with the pipe format.
If I start saving the mp4 stream as a file and attempt to play it sometime later but before I stop recording process, vlc refuses to do so, and complains about the absence of moov box / atom. It only succeeds once the recording/saving is stopped. Therefore, with my limited knowledge, I speculate that a moov box / atom, which is needed to play an mp4 file, is added to the saved file only after the saving / recording stops. This is probably not the case with formats like wav, mp2, etc. I think this is why I failed my attempts so far.
If one kills the vlc process or terminates it rather than manually stopping, the mp4 file is still unreadable, probably because of the same issue, i.e. moov box / atom was not added.
None of the transcode options vlc is capable of works for mp4a stream with the vlc version that came with Mandriva 2009.0 (0.9.3 Grishenko), in case anybody else was trying.
Regards.