DSP_CAP_DUPLEX
res &= ~DSP_CAP_DUPLEX;
result = DSP_CAP_TRIGGER | DSP_CAP_MMAP | DSP_CAP_DUPLEX | DSP_CAP_REALTIME;
if (snd_pcm_oss_get_caps(pcm_oss_file) & DSP_CAP_DUPLEX)