Re: CDDA playback on Pismo (and other newer models)

Using the ATAPI CD drivers there are underruns with significant
dropouts every couple of seconds. Various hdparms and cdparanoia
parms were tried with no significant change. These include various
transfers modes and cdparanoia's buffer (-n) and speed (-S)
parms and various data formats. Piping cdparanoia out to /dev/null
showed data rates of 46 sectors/sec at -S1, 65sps at -S8, and
133sps at -S12 and above (also the default and no significant
changes with different transfer modes and -n values). At the higher
speeds (>-S11) there is a high-level of continuous head-seek noise,
suggesting a lot of overruns and reseeks on the CD i/f side.

Rebuilding the kernel to use SCSI generic devices with IDE SCSI
emulation produced much better, even usable, results. At startup
there are still a couple of dropouts in the first few seconds,
but after that the playback is clean across multiple tracks (even
with a concurrent kernel compile). Piping cdparanoia to /dev/null
shows data rates of 187sectors/sec at all -S settings (and default).
From the the drive's spin-up sounds it seems to always be in
high-speed mode, but unlike the ATAPI driver, there is little
head movement noise.

I think the problem is more with cdparanoia. I think it's more or less
synchronous, it doesn't have a thread that collects datas while another
outputs sounds. I've looked at cdparanoia sources some time ago, and I
think and intermediate step of buffering is necessary.


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