From 2cfba1ff56314ccb7caffa56316a18bcf19c7fce Mon Sep 17 00:00:00 2001
From: clangen <casey.langen@gmail.com>
Date: Thu, 9 Jun 2016 01:01:47 -0700
Subject: [PATCH] Added volume support; ALSA doesn't seem to support this
 natively so we do it in software.

---
 src/contrib/alsaout/AlsaOut.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/contrib/alsaout/AlsaOut.cpp b/src/contrib/alsaout/AlsaOut.cpp
index 1f5ead2a0..70b950f64 100755
--- a/src/contrib/alsaout/AlsaOut.cpp
+++ b/src/contrib/alsaout/AlsaOut.cpp
@@ -188,7 +188,8 @@ void AlsaOut::Resume() {
 }
 
 void AlsaOut::SetVolume(double volume) {
-
+    LOCK("set volume");
+    this->volume = volume;
 }
 
 void AlsaOut::WriteLoop() {
@@ -219,6 +220,17 @@ void AlsaOut::WriteLoop() {
 
             if (next) {
                 size_t samples = next->buffer->Samples();
+                size_t channels = next->buffer->Channels();
+
+                float volume = (float) this->volume;
+
+                /* software volume; alsa doesn't support this internally. this is about
+                as terrible as an algorithm can be -- it's just a linear ramp. */
+                float *buffer = next->buffer->BufferPointer();
+                for (size_t i = 0; i < samples * channels; i++) {
+                    (*buffer) *= volume;
+                    ++buffer;
+                }
 
                 err = snd_pcm_writei(
                     this->pcmHandle,