path: root/sound/isa
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authorTakashi Sakamoto <o-takashi@sakamocchi.jp>2018-10-01 04:11:49 +0900
committerTakashi Iwai <tiwai@suse.de>2018-10-02 17:28:29 +0200
commit5950229582bc4e5e332247dd9ec11e6fe85659e1 (patch)
tree15b387e2ffb9371d55899b7c9a4ade37b762f338 /sound/isa
parent96395e86e3f4c7f520bb7c53c7eee41b1992ebc2 (diff)
ALSA: firewire-lib: add PCM rules to obsolete PCM constraints based on LCM of SYT_INTERVAL
In blocking mode of IEC 61883-1/6, when one isochronous packet includes data for events, the data is for the same number of events as SYT_INTERVAL decided according to sampling transmission frequency (SFC). IEC 61883-1/6 engine of ALSA firewire stack applies constraints of period and buffer size of PCM intermediate buffer of PCM substream. At present, this constraint is designed to round the size up/down to 32 frames. This value comes from the least common multiple (LCM) of SYT_INTERVAL. Although this looks to work well, in lower sampling rate, applications are not allowed to set size of period quite near period time constraint (at present 5 msec per period). This commit adds PCM rules for period/buffer size and rate to obsoletes the constraints based on LCM. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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