HYL_OK3568_LINUX/buildroot/package/gstreamer1/gst1-plugins-good/0011-v4l2-Support-setting-v4l2-min-buffers.patch

From 27c5416b50ff2a62ca38c82bb45196e1e8ad1035 Mon Sep 17 00:00:00 2001
From: Jeffy Chen <jeffy.chen@rock-chips.com>
Date: Thu, 23 Jun 2022 16:04:18 +0800
Subject: [PATCH 11/12] v4l2: Support setting v4l2 min buffers

Tested with:
gst-launch-1.0 v4l2src min-buffers=32 ! waylandsink ts-offset=1000000000

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---
 sys/v4l2/gstv4l2object.c | 24 ++++++++++++++++++++++++
 sys/v4l2/gstv4l2object.h |  3 ++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 09fabf0..4c8791a 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -58,6 +58,8 @@ GST_DEBUG_CATEGORY_EXTERN (v4l2_debug);
 #define GST_V4L2_DEFAULT_WIDTH          320
 #define GST_V4L2_DEFAULT_HEIGHT         240
 
+static guint DEFAULT_PROP_MIN_BUFFERS = 0;
+
 enum
 {
   PROP_0,
@@ -312,6 +314,11 @@ void
 gst_v4l2_object_install_properties_helper (GObjectClass * gobject_class,
     const char *default_device)
 {
+  const gchar *buf = g_getenv ("GST_V4L2_MIN_BUFS");
+
+  if (buf)
+    DEFAULT_PROP_MIN_BUFFERS = atoi (buf);
+
   g_object_class_install_property (gobject_class, PROP_DEVICE,
       g_param_spec_string ("device", "Device", "Device location",
           default_device, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
@@ -431,6 +438,12 @@ gst_v4l2_object_install_properties_helper (GObjectClass * gobject_class,
           "When enabled, the pixel aspect ratio will be enforced", TRUE,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
+  g_object_class_install_property (gobject_class, PROP_MIN_BUFFERS,
+      g_param_spec_uint ("min-buffers", "Min buffers",
+          "Override the driver's min buffers (0 means auto)",
+          0, VIDEO_MAX_FRAME, DEFAULT_PROP_MIN_BUFFERS,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   gst_type_mark_as_plugin_api (GST_TYPE_V4L2_DEVICE_FLAGS, 0);
   gst_type_mark_as_plugin_api (GST_TYPE_V4L2_TV_NORM, 0);
   gst_type_mark_as_plugin_api (GST_TYPE_V4L2_IO_MODE, 0);
@@ -548,6 +561,8 @@ gst_v4l2_object_new (GstElement * element,
     v4l2object->munmap = munmap;
   }
 
+  v4l2object->min_buffers = DEFAULT_PROP_MIN_BUFFERS;
+
   return v4l2object;
 }
 
@@ -715,6 +730,9 @@ gst_v4l2_object_set_property_helper (GstV4l2Object * v4l2object,
     case PROP_FORCE_ASPECT_RATIO:
       v4l2object->keep_aspect = g_value_get_boolean (value);
       break;
+    case PROP_MIN_BUFFERS:
+      v4l2object->min_buffers = g_value_get_uint (value);
+      break;
     default:
       return FALSE;
       break;
@@ -812,6 +830,9 @@ gst_v4l2_object_get_property_helper (GstV4l2Object * v4l2object,
     case PROP_FORCE_ASPECT_RATIO:
       g_value_set_boolean (value, v4l2object->keep_aspect);
       break;
+    case PROP_MIN_BUFFERS:
+      g_value_set_uint (value, v4l2object->min_buffers);
+      break;
     default:
       return FALSE;
       break;
@@ -824,6 +845,9 @@ gst_v4l2_get_driver_min_buffers (GstV4l2Object * v4l2object)
 {
   struct v4l2_control control = { 0, };
 
+  if (v4l2object->min_buffers)
+    return;
+
   g_return_if_fail (GST_V4L2_IS_OPEN (v4l2object));
 
   if (V4L2_TYPE_IS_OUTPUT (v4l2object->type))
diff --git a/sys/v4l2/gstv4l2object.h b/sys/v4l2/gstv4l2object.h
index 3a5c961..276d58f 100644
--- a/sys/v4l2/gstv4l2object.h
+++ b/sys/v4l2/gstv4l2object.h
@@ -246,7 +246,8 @@ GType gst_v4l2_object_get_type (void);
     PROP_CAPTURE_IO_MODE,     \
     PROP_EXTRA_CONTROLS,      \
     PROP_PIXEL_ASPECT_RATIO,  \
-    PROP_FORCE_ASPECT_RATIO
+    PROP_FORCE_ASPECT_RATIO,  \
+    PROP_MIN_BUFFERS
 
 /* create/destroy */
 GstV4l2Object*  gst_v4l2_object_new       (GstElement * element,
-- 
2.20.1