From b2109aadba5c960a01bce80e58f56c0d9d84f473 Mon Sep 17 00:00:00 2001
From: jens1608 <47902940+jens1608@users.noreply.github.com>
Date: Wed, 27 Mar 2024 19:53:43 +0100
Subject: [PATCH] Turn off output on idle (#25)

* Update main.c

Trying to disable PCM while waiting for data

* Update main.c

Made disabling PCM during underrun configurable

* Update main.c

Added debug log messages

* Fix formatting

* Update README

---------

Co-authored-by: Tucker Kern <tuckkern@gmail.com>
---
 README.md     |  1 +
 source/main.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/README.md b/README.md
index 83ec1f1..c44b8c8 100644
--- a/README.md
+++ b/README.md
@@ -102,6 +102,7 @@ Check `raspdif --help` for additional optional arguments to tweak behavior.
 ```
 Usage: raspdif [OPTION...]
 
+  -d, --disable-pcm-on-idle  Disable PCM during underrun.
   -f, --format=FORMAT        Set audio sample format to s16le or s24le.
                              Default: s16le
   -i, --input=INPUT_FILE     Read data from file instead of stdin.
diff --git a/source/main.c b/source/main.c
index b6012dd..2c7e67c 100644
--- a/source/main.c
+++ b/source/main.c
@@ -34,6 +34,7 @@ typedef struct raspdif_arguments_t
   const char* file;
   bool verbose;
   bool keep_alive;
+  bool pcm_disable;
   double sample_rate;
   raspdif_format_t format;
 } raspdif_arguments_t;
@@ -45,6 +46,7 @@ static struct argp_option options[] = {
   {"rate", 'r', "RATE", 0, "Set audio sample rate. Default: 44.1 kHz"},
   {"format", 'f', "FORMAT", 0, "Set audio sample format to s16le or s24le. Default: s16le"},
   {"no-keep-alive", 'k', 0, 0, "Don't send silent noise during underrun."},
+  {"disable-pcm-on-idle", 'd', 0, 0, "Disable PCM during underrun."},
   {"verbose", 'v', 0, 0, "Enable debug messages."},
   {0},
 };
@@ -91,6 +93,10 @@ static error_t parse_opt(int key, char* arg, struct argp_state* state)
       arguments->keep_alive = false;
       break;
 
+    case 'd':
+      arguments->pcm_disable = true;
+      break;
+
     default:
       return ARGP_ERR_UNKNOWN;
   }
@@ -526,12 +532,24 @@ int main(int argc, char* argv[])
       // Zero fill the sample buffers for silence
       raspdif_fill_buffers(buffer_index, &block, arguments.format, arguments.sample_rate, arguments.keep_alive);
 
+      if (arguments.pcm_disable)
+      {
+        bcm283x_pcm_enable(false, false);
+        LOGD(TAG, "PCM disabled.");
+      }
+
       // Wait for file to be readable
       struct pollfd poll_list;
       poll_list.fd = fileno(file);
       poll_list.events = POLLIN;
       poll(&poll_list, 1, -1);
 
+      if (arguments.pcm_disable)
+      {
+        bcm283x_pcm_enable(true, false);
+        LOGD(TAG, "PCM enabled.");
+      }
+
       // Resume read loop
       LOGD(TAG, "Data available.");
       continue;