audio: align audio_generic_write with audio_pcm_hw_run_out
The function audio_generic_write should work exactly like
audio_pcm_hw_run_out. It's a very similar function working on a
different buffer.
This patch significantly reduces the number of drop-outs with
the DirectSound backend. To hear the difference start qemu with
-audiodev dsound,id=audio0,out.mixing-engine=off and play a
song in the guest with and without this patch.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-6-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/audio/audio.c b/audio/audio.c
index 341edc4..8587e3d 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -1484,12 +1484,34 @@
size_t audio_generic_write(HWVoiceOut *hw, void *buf, size_t size)
{
- size_t dst_size, copy_size;
- void *dst = hw->pcm_ops->get_buffer_out(hw, &dst_size);
- copy_size = MIN(size, dst_size);
+ size_t total = 0;
- memcpy(dst, buf, copy_size);
- return hw->pcm_ops->put_buffer_out(hw, dst, copy_size);
+ while (total < size) {
+ size_t dst_size = size - total;
+ size_t copy_size, proc;
+ void *dst = hw->pcm_ops->get_buffer_out(hw, &dst_size);
+
+ if (dst_size == 0) {
+ break;
+ }
+
+ copy_size = MIN(size - total, dst_size);
+ if (dst) {
+ memcpy(dst, (char *)buf + total, copy_size);
+ }
+ proc = hw->pcm_ops->put_buffer_out(hw, dst, copy_size);
+ total += proc;
+
+ if (proc == 0 || proc < copy_size) {
+ break;
+ }
+ }
+
+ if (hw->pcm_ops->run_buffer_out) {
+ hw->pcm_ops->run_buffer_out(hw);
+ }
+
+ return total;
}
size_t audio_generic_read(HWVoiceIn *hw, void *buf, size_t size)
