вс, 5 мая 2019 г. в 01:41, Georg Chini <georg@xxxxxxxx>: > > On 04.05.19 20:54, Alexander E. Patrakov wrote: > > сб, 4 мая 2019 г. в 20:25, Georg Chini <georg@xxxxxxxx>: > >> On 04.05.19 16:42, Alexander E. Patrakov wrote: > >>> сб, 4 мая 2019 г. в 16:17, Georg Chini <georg@xxxxxxxx>: > >>>> Here is the new version of the header file, based on your feedback. > >>>> The main changes are: > >>>> > >>>> - The create_filter() function now receives the channel maps for input > >>>> and output. > >>>> - The create_filter() function receives a kill_filter() function and a > >>>> module pointer > >>>> which makes it possible for the filter to initiate unloading of the > >>>> module if it > >>>> detects that it is no longer applicable. > >>>> - An output_changed() function was added which communicates current sink > >>>> and port name to the filter, so that it can detect if the output has > >>>> changed. > >>>> > >>>> Also I did a bit of cleanup and added a few more comments. Hope it looks > >>>> better now. > >>> It definitely looks better. > >>> > >>> I am still confused about disable_rewind and max_latency. Let's > >>> suppose that someone wants to implement a rewindable filter. In this > >>> case, they need to keep history, because PulseAudio can ask the filter > >>> to rewind some samples. And, as it is not allowed to say "no", they > >>> must keep enough history to satisfy any possible rewind request. But > >>> some upper bound must exist. Do I understand correctly that > >>> max_latency serves as such upper bound? > >>> > >>> Regarding the non-rewindable filters, we do need to limit the latency, > >>> but I believe it is wrong for each individual filter to specify its > >>> own value for such limit. It should be a global policy (the same value > >>> for all non-rewindable sinks), and I don't see any reason for the > >>> filter to be able to influence it. > >>> > >>> Therefore, I believe these two fields can be replaced by one, > >>> max_rewind, which is the size of history, in samples, that the filter > >>> is willing to keep. Zero means a non-rewindable filter. > >>> > >> That sounds like a good suggestion. I would however think > >> that it is better if 0 means that the filter will rewind as far as > >> PA wants it to. There may be filters that are stateless (like the > >> trivial amplifier example). We could use -1 to disable rewinding. > > OK. > > > >> That would also mean to limit the latency to whatever the filter > >> can rewind, correct? I would use the maximum of max_rewind > >> and the default latency for non-rewindable filters as the > >> max_latency value then, because I don't think it makes sense > >> to set the maximum latency even smaller than for non-rewindable > >> filters. > > Makes sense. > > > >> What do you think is reasonable for non-rewindable filters? > >> 50 ms? > > There were different opinions on that matter. 50 ms is indeed in a > > range that I would agree to. > > > Just finished the next version. Does this look OK to you now? I think that the only significant difference is the addition of error codes. I cannot comment on them with any authority, but the majority do not seem applicable to filters. Probably we need some mechanism that allows arbitrary error strings to be logged? -- Alexander E. Patrakov _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
