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Quoting Volker Rümelin: "try-poll=on tells the ALSA backend to try to use an event loop instead of the audio timer. This works most of the time. But the poll event handler in the ALSA backend has a bug. For example, if the guest can't provide enough audio frames in time, the ALSA buffer is only partly full and the event handler will be called again and again on every iteration of the main loop. This increases the processor load and the guest has less processor time to provide new audio frames in time. I have two examples where a guest can't recover from this situation and the guest seems to hang." One reproducer I've found is booting MorphOS demo iso on qemu-system-ppc -machine pegasos2 -audio alsa which should play a startup sound but instead it freezes. Even when it does not hang it plays choppy sound. Volker suggested using command line to set try-poll=off saying: "The try-poll=off arguments are typically necessary, because the alsa backend has a design issue with try-poll=on. If the guest can't provide enough audio frames, it's really unhelpful to ask for new audio frames on every main loop iteration until the guest can provide enough audio frames. Timer based playback doesn't have that problem." But users cannot easily find this option and having a non-working default is really unhelpful so to make life easier just set it to false by default which works until the issue with the alsa backend can be fixed. Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu> Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com> [ Marc-André - Updated QAPI and CLI doc ] Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20250316002046.D066A4E6004@zero.eik.bme.hu> |
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| .. | ||
| alsaaudio.c | ||
| audio-hmp-cmds.c | ||
| audio.c | ||
| audio.h | ||
| audio_int.h | ||
| audio_template.h | ||
| audio_win_int.c | ||
| audio_win_int.h | ||
| coreaudio.m | ||
| dbusaudio.c | ||
| dsound_template.h | ||
| dsoundaudio.c | ||
| jackaudio.c | ||
| meson.build | ||
| mixeng.c | ||
| mixeng.h | ||
| mixeng_template.h | ||
| noaudio.c | ||
| ossaudio.c | ||
| paaudio.c | ||
| pwaudio.c | ||
| rate_template.h | ||
| sdlaudio.c | ||
| sndioaudio.c | ||
| spiceaudio.c | ||
| trace-events | ||
| trace.h | ||
| wavaudio.c | ||
| wavcapture.c | ||