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a module pointer which makes it possible for the filter to initiate unloading of the module if it detects that it is no longer applicable.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. 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. What do you think is reasonable for non-rewindable filters? 50 ms? _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
