diff options
Diffstat (limited to 'hw/audio/asc.c')
| -rw-r--r-- | hw/audio/asc.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/hw/audio/asc.c b/hw/audio/asc.c index 9084708eaf..0f36b4ce9b 100644 --- a/hw/audio/asc.c +++ b/hw/audio/asc.c @@ -341,6 +341,21 @@ static void asc_out_cb(void *opaque, int free_b) } if (!generated) { + /* Workaround for audio underflow bug on Windows dsound backend */ + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + int silent_samples = muldiv64(now - s->fifo_empty_ns, + NANOSECONDS_PER_SECOND, ASC_FREQ); + + if (silent_samples > ASC_FIFO_CYCLE_TIME / 2) { + /* + * No new FIFO data within half a cycle time (~23ms) so fill the + * entire available buffer with silence. This prevents an issue + * with the Windows dsound backend whereby the sound appears to + * loop because the FIFO has run out of data, and the driver + * reuses the stale content in its circular audio buffer. + */ + AUD_write(s->voice, s->silentbuf, samples << s->shift); + } return; } @@ -618,6 +633,7 @@ static void asc_unrealize(DeviceState *dev) ASCState *s = ASC(dev); g_free(s->mixbuf); + g_free(s->silentbuf); AUD_remove_card(&s->card); } @@ -642,6 +658,9 @@ static void asc_realize(DeviceState *dev, Error **errp) s->samples = AUD_get_buffer_size_out(s->voice) >> s->shift; s->mixbuf = g_malloc0(s->samples << s->shift); + s->silentbuf = g_malloc0(s->samples << s->shift); + memset(s->silentbuf, 0x80, s->samples << s->shift); + /* Add easc registers if required */ if (s->type == ASC_TYPE_EASC) { memory_region_add_subregion(&s->asc, ASC_EXTREG_OFFSET, |