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qemu: fix HDA recording latency

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Very long latency occurs for audio inputs when simulating an Intel HDA device.

Patch courtesy of Volker Rümeling.
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg03336.html
This commit is contained in:
Tim Jäger 2017-08-06 20:19:32 -07:00 committed by Franz Pletz
parent 378c6d7063
commit 0c1c3d2b99
2 changed files with 36 additions and 1 deletions
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3
pkgs/applications/virtualization/qemu/default.nix
View file

@ -55,7 +55,8 @@ stdenv.mkDerivation rec {
enableParallelBuilding = true;
patches = [ ./no-etc-install.patch ]
++ optional nixosTestRunner ./force-uid0-on-9p.patch;
++ optional nixosTestRunner ./force-uid0-on-9p.patch
++ optional pulseSupport ./fix-hda-recording.patch;
hardeningDisable = [ "stackprotector" ];

34
pkgs/applications/virtualization/qemu/fix-hda-recording.patch Normal file
View file

@ -0,0 +1,34 @@
diff --git a/audio/paaudio.c b/audio/paaudio.c
index fea6071..c1169d4 100644
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -608,6 +608,7 @@ static int qpa_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
{
int error;
pa_sample_spec ss;
+ pa_buffer_attr ba;
struct audsettings obt_as = *as;
PAVoiceIn *pa = (PAVoiceIn *) hw;
paaudio *g = pa->g = drv_opaque;
@@ -616,6 +617,12 @@ static int qpa_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
ss.channels = as->nchannels;
ss.rate = as->freq;
+ ba.fragsize = pa_frame_size (&ss) * g->conf.samples;
+ ba.maxlength = 5 * ba.fragsize;
+ ba.tlength = -1;
+ ba.prebuf = -1;
+ ba.minreq = -1;
+
obt_as.fmt = pa_to_audfmt (ss.format, &obt_as.endianness);
pa->stream = qpa_simple_new (
@@ -625,7 +632,7 @@ static int qpa_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
g->conf.source,
&ss,
NULL, /* channel map */
- NULL, /* buffering attributes */
+ &ba, /* buffering attributes */
&error
);
if (!pa->stream) {