On Fri, Oct 24, 2014 at 12:38:16AM +0600, Alexander E. Patrakov wrote: > 24.10.2014 00:08, Andrew Eikum wrote: > >I have a patch in-hand which improves the current driver > >significantly, but it isn't enough to fix the USB devices problem. If > >someone wants to review the winealsa driver with the patch applied and > >discuss solutions, let me know. I'd love to get this problem solved. > > If you send me the patch, I promise to have a look at it. But, see > my other reply why there cannot be a full solution within the ALSA > API. > I've attached the patch here. It's been a while since I've worked on this, so I'm fuzzy on the details. It should apply on any recent Wine version, including today's. There's a comment above alsa_write_data() describing how the buffer is laid out and what the offsets point to. alsa_write_data() is where we actually send data to ALSA. AudioClient_Stop() and _Start() are where the stream is rewound and paused. AudioClient_Initialize() is where the device setup occurs. AudioClock_GetPosition() returns the number of played frames. Note that we explicitly toggle handle_underrun to TRUE in make_handle_underrun_config(). Toggling this off does seem to have an impact on USB devices. The underruns aren't fixed in either setting, but it's worth playing with. If I remember correctly, the problem with USB devices is that snd_pcm_avail_update() updates too infrequently. To keep low latency, we set up a buffer size of four ALSA periods (about 40ms, I think). But, snd_pcm_avail_update() updates less frequently than that, so we constantly hit underruns. Some Windows applications behave very badly with large latencies. I think the issue was more complicated than that, but I've forgotten the details in the meantime... I believe disabling BATCH mode on USB devices "fixes" everything with this patch applied, but I presume there was a reason it was introduced in the first place (see PA bug 66962). I could be wrong here, I never totally understood the issue. There are two important programs that I test with: -Any well-behaved dsound program (I use the "American McGee's Alice Demo"; "Marble Arena 1" is another good test program.) -Microsoft Games's Pinball (This uses winmm very abusively, with lots of starts and stops. Good at testing latency.) Once the driver behaves well on those two, I usually run it through the rest of my audio application gauntlet to look for issues. Happy for feedback on any part of the driver. Thanks, Andrew -------------- next part -------------- A non-text attachment was scrubbed... Name: winealsa.patch Type: text/x-diff Size: 24452 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20141023/8fb94994/attachment.patch>
