From fd00d16361d24718e59dbd90ad290e381500eb5c Mon Sep 17 00:00:00 2001
From: Michael Tretter <m.tretter@pengutronix.de>
Date: Fri, 20 Mar 2020 17:00:36 +0100
Subject: [PATCH] gst: add properties for limits of negotiated buffers

By default, the pipewiresrc tries to negotiate 16 buffers. This value is
hard coded in the pipewiresrc. If the buffers are large, this could lead
to an undesirably high memory usage. Applications that know about the
buffer size and that fewer buffers are sufficient should be able to
configure the limits for the number of buffers that are negotiated.

Therefore, add the min-buffers and max-buffers properties to the
pipewiresrc to enable applications to configure limits for the number of
negotiated buffers.
---
 src/gst/gstpipewiresrc.c | 45 +++++++++++++++++++++++++++++++++++++++-
 src/gst/gstpipewiresrc.h |  2 ++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/gst/gstpipewiresrc.c b/src/gst/gstpipewiresrc.c
index 95d262373..d2e9b3213 100644
--- a/src/gst/gstpipewiresrc.c
+++ b/src/gst/gstpipewiresrc.c
@@ -60,6 +60,8 @@ GST_DEBUG_CATEGORY_STATIC (pipewire_src_debug);
 #define GST_CAT_DEFAULT pipewire_src_debug
 
 #define DEFAULT_ALWAYS_COPY     false
+#define DEFAULT_MIN_BUFFERS     1
+#define DEFAULT_MAX_BUFFERS     INT32_MAX
 
 enum
 {
@@ -68,6 +70,8 @@ enum
   PROP_CLIENT_NAME,
   PROP_STREAM_PROPERTIES,
   PROP_ALWAYS_COPY,
+  PROP_MIN_BUFFERS,
+  PROP_MAX_BUFFERS,
   PROP_FD,
 };
 
@@ -124,6 +128,14 @@ gst_pipewire_src_set_property (GObject * object, guint prop_id,
       pwsrc->always_copy = g_value_get_boolean (value);
       break;
 
+    case PROP_MIN_BUFFERS:
+      pwsrc->min_buffers = g_value_get_int (value);
+      break;
+
+    case PROP_MAX_BUFFERS:
+      pwsrc->max_buffers = g_value_get_int (value);
+      break;
+
     case PROP_FD:
       pwsrc->fd = g_value_get_int (value);
       break;
@@ -157,6 +169,14 @@ gst_pipewire_src_get_property (GObject * object, guint prop_id,
       g_value_set_boolean (value, pwsrc->always_copy);
       break;
 
+    case PROP_MIN_BUFFERS:
+      g_value_set_int (value, pwsrc->min_buffers);
+      break;
+
+    case PROP_MAX_BUFFERS:
+      g_value_set_int (value, pwsrc->max_buffers);
+      break;
+
     case PROP_FD:
       g_value_set_int (value, pwsrc->fd);
       break;
@@ -282,6 +302,24 @@ gst_pipewire_src_class_init (GstPipeWireSrcClass * klass)
                                                          G_PARAM_READWRITE |
                                                          G_PARAM_STATIC_STRINGS));
 
+  g_object_class_install_property (gobject_class,
+                                   PROP_MIN_BUFFERS,
+                                   g_param_spec_int ("min-buffers",
+                                                     "Min Buffers",
+                                                     "Minimum number of buffers to negotiate with PipeWire",
+                                                     1, G_MAXINT, DEFAULT_MIN_BUFFERS,
+                                                     G_PARAM_READWRITE |
+                                                     G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (gobject_class,
+                                   PROP_MAX_BUFFERS,
+                                   g_param_spec_int ("max-buffers",
+                                                     "Max Buffers",
+                                                     "Maximum number of buffers to negotiate with PipeWire",
+                                                     1, G_MAXINT, DEFAULT_MAX_BUFFERS,
+                                                     G_PARAM_READWRITE |
+                                                     G_PARAM_STATIC_STRINGS));
+
    g_object_class_install_property (gobject_class,
                                     PROP_FD,
                                     g_param_spec_int ("fd",
@@ -325,6 +363,8 @@ gst_pipewire_src_init (GstPipeWireSrc * src)
   GST_OBJECT_FLAG_SET (src, GST_ELEMENT_FLAG_PROVIDE_CLOCK);
 
   src->always_copy = DEFAULT_ALWAYS_COPY;
+  src->min_buffers = DEFAULT_MIN_BUFFERS;
+  src->max_buffers = DEFAULT_MAX_BUFFERS;
   src->fd = -1;
 
   g_queue_init (&src->queue);
@@ -699,11 +739,14 @@ on_param_changed (void *data, uint32_t id,
     const struct spa_pod *params[2];
     struct spa_pod_builder b = { NULL };
     uint8_t buffer[512];
+    uint32_t buffers = buffers = CLAMP (16, pwsrc->min_buffers, pwsrc->max_buffers);
 
     spa_pod_builder_init (&b, buffer, sizeof (buffer));
     params[0] = spa_pod_builder_add_object (&b,
         SPA_TYPE_OBJECT_ParamBuffers, SPA_PARAM_Buffers,
-        SPA_PARAM_BUFFERS_buffers, SPA_POD_CHOICE_RANGE_Int(16, 1, INT32_MAX),
+        SPA_PARAM_BUFFERS_buffers, SPA_POD_CHOICE_RANGE_Int(buffers,
+                                                            pwsrc->min_buffers,
+                                                            pwsrc->max_buffers),
         SPA_PARAM_BUFFERS_blocks,  SPA_POD_CHOICE_RANGE_Int(0, 1, INT32_MAX),
         SPA_PARAM_BUFFERS_size,    SPA_POD_CHOICE_RANGE_Int(0, 0, INT32_MAX),
         SPA_PARAM_BUFFERS_stride,  SPA_POD_CHOICE_RANGE_Int(0, 0, INT32_MAX),
diff --git a/src/gst/gstpipewiresrc.h b/src/gst/gstpipewiresrc.h
index 02374f6d3..c80e13ee0 100644
--- a/src/gst/gstpipewiresrc.h
+++ b/src/gst/gstpipewiresrc.h
@@ -61,6 +61,8 @@ struct _GstPipeWireSrc {
   gchar *path;
   gchar *client_name;
   gboolean always_copy;
+  gint min_buffers;
+  gint max_buffers;
   int fd;
 
   gboolean negotiated;