From: Mike Brady <mikebrady@eircom.net>
Date: Wed, 17 Aug 2016 18:59:26 +0000 (+0100)
Subject: add ability to not use mmap
X-Git-Tag: 2.8.4.6~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c1e07b98d1f96d3caef0fb6d7f678857800bea07;p=thirdparty%2Fshairport-sync.git

add ability to not use mmap
---

diff --git a/audio_alsa.c b/audio_alsa.c
index 76ab58c6..ad5b0c74 100644
--- a/audio_alsa.c
+++ b/audio_alsa.c
@@ -205,6 +205,15 @@ static int init(int argc, char **argv) {
         die("Invalid disable_synchronization option choice \"%s\". It should be \"yes\" or \"no\"");
     }
     
+    /* Get the use_mmap_if_available setting. */
+    if (config_lookup_string(config.cfg, "alsa.use_mmap_if_available", &str)) {
+      if (strcasecmp(str, "no") == 0)
+        config.no_mmap = 1;
+      else if (strcasecmp(str, "yes") == 0)
+        config.no_mmap = 0;
+      else
+        die("Invalid use_mmap_if_available option choice \"%s\". It should be \"yes\" or \"no\"");
+    }
     /* Get the optional period size value */
     if (config_lookup_int(config.cfg, "alsa.period_size",
                           &value)) {
@@ -393,7 +402,7 @@ int open_alsa_device(void) {
         alsa_out_dev);
   }
 
-  if (snd_pcm_hw_params_set_access(alsa_handle, alsa_params, SND_PCM_ACCESS_MMAP_INTERLEAVED) >= 0) {
+  if ((config.no_mmap == 0) && (snd_pcm_hw_params_set_access(alsa_handle, alsa_params, SND_PCM_ACCESS_MMAP_INTERLEAVED) >= 0)) {
   	if (output_method_signalled==0) {
   		debug(1,"Output written using MMAP");
   		output_method_signalled=1;
diff --git a/common.h b/common.h
index a67f95b4..32ee301d 100644
--- a/common.h
+++ b/common.h
@@ -66,6 +66,7 @@ typedef struct {
   int udp_port_range;
   int ignore_volume_control;
   int no_sync; // disable synchronisation, even if it's available
+  int no_mmap; // disable use of mmap-based output, even if it's available
   int resyncthreshold; // if it get's out of whack my more than this, resync. Zero means never
                        // resync.
   int allow_session_interruption;
diff --git a/scripts/shairport-sync.conf b/scripts/shairport-sync.conf
index 05840df9..bb737ee8 100644
--- a/scripts/shairport-sync.conf
+++ b/scripts/shairport-sync.conf
@@ -62,7 +62,7 @@ alsa =
 //  audio_backend_buffer_desired_length = 6615; // If set too small, buffer underflow occurs on low-powered machines. Too long and the response times with software mixer become annoying.
 //  disable_synchronization = "no"; // Set to "yes" to disable synchronization. Default is "no".
 //  period_size = <number>; // Use this optional advanced setting to set the alsa period size near to this value
-//  buffer_size = <number>; // Use this optional advanced setting to set the alsa buffer size near to this value
+//  use_mmap_if_available = "yes"; // Use this optional advanced setting to control whether MMAP-based output is used to communicate  with the DAC. Default is "yes"
 };
 
 // These are parameters for the "pipe" audio back end, a back end that directs raw CD-style audio output to a pipe. No interpolation is done.
diff --git a/shairport.c b/shairport.c
index df577348..72ea8d0c 100644
--- a/shairport.c
+++ b/shairport.c
@@ -1012,6 +1012,7 @@ int main(int argc, char **argv) {
   debug(1, "ignore_volume_control is %d.", config.ignore_volume_control);
   debug(1, "playback_mode is %d (0-stereo, 1-mono).", config.playback_mode);
   debug(1, "disable_synchronization is %d.", config.no_sync);
+  debug(1, "use_mmap_if_available is %d.", config.no_mmap ? 0 : 1);
   debug(1, "audio backend desired buffer length is %d.",
         config.audio_backend_buffer_desired_length);
   debug(1, "audio backend latency offset is %d.", config.audio_backend_latency_offset);