[MPlayer-dev-eng] ALSA issue, r29549 fix seems incomplete

[Sylvain Bertrand]

> alsa-init: got buffersize=65536
> alsa-init: got period size 1024
> alsa: 48000 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little Endian

alsa-init: got buffersize=216000
alsa-init: got period size 6000
alsa: 48000 Hz/6 channels/12 bpf/216000 bytes buffer/Signed 16 bit Little Endian

When I dump the initial len and the outburst in the play function, I
get len=65536 (64k) (sometimes 19392) and outburst=72000 (6000*2*6
which is set in init function).
Off course, the truncated len is then 0.