Jaroslav Kysela wrote: > > On Fri, 11 Oct 2002, Abramo Bagnara wrote: > > > I really don't understand why you've added another ioctl and another > > function to replicate in all PCM classes. > > snd_pcm_delay existence is enough to implement that. > > I'm missing something? > > You're completely right, but in my eyes, the avail ioctl looks much better > for kernel space (it's a base value for computing delay, computing avail > from delay needs twice substractions which doesn't look very good). > Unfortunately, delay ioctl was first, and we should keep binary > compatibility for 2.5, so we should leave both ioctls there. In library, > we can remove the delay operation from chains and use avail to compute it > as well to simplify code.
No, you can't. The semantic of snd_pcm_delay is: "How many frames are current application read/write pointer far away from 'now' (i.e. real world sound)?" It's *not* simply equivalent to buffer_size - avail (playback) or avail (capture). It's designed to take in account also olatencies introduced by other things (network layer, hardware limits, etc.). Although I don't understand why you think that snd_pcm_avail is needed when we have the right (and safe) snd_pcm_avail_update, it can be implemented calling snd_pcm_delay (so to update hw pointer) and then computing the avail count using the mmap'ed counters. Of course this can't work for chained PCM (and this is why we have snd_pcm_avail_update). I think you should revert your patch (and to force yourself to believe a bit more in peer review before important changes although it seems I'm beating a dead horse here). -- Abramo Bagnara mailto:abramo.bagnara@;libero.it Opera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
