[Spice-devel] [PATCH v2 spice-streaming-agent] gst-plugin: receive encoder properties as command parameters

[Snir Sheriber]

From: test <test at localhost.localdomain>

This allows to set plugin key=value properties on run time.
To add encoder plugin property use the following syntax:
-c gst.prop="property=value" -c gst.prop="property2=value2"...
Make sure syntax is accurate and that the property is supported by
the chosen plugin, wrong properties may ignored silently.

Signed-off-by: Snir Sheriber <ssheribe at redhat.com>
---

Difference from v1:
-Variables naming
-Using vector of pairs
-Add warnings for wrong input
-Set propeties after log msg
-Fix commit msg

*There is only basic input validation, assuming the user is
 accurate with the properties he sets.
 Currently the code checks property name exists for the encoder
 object, i had a version that checks also the value matches the
 property type but it seems to be over-coding for this purpose.
 
---
 src/gst-plugin.cpp | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/gst-plugin.cpp b/src/gst-plugin.cpp
index 4e802f1..3270cce 100644
--- a/src/gst-plugin.cpp
+++ b/src/gst-plugin.cpp
@@ -35,6 +35,7 @@ struct GstreamerEncoderSettings
     int fps = 25;
     SpiceVideoCodecType codec = SPICE_VIDEO_CODEC_TYPE_H264;
     std::string encoder;
+    std::vector<std::pair<std::string, std::string>> prop_pairs;
 };
 
 template <typename T>
@@ -179,11 +180,18 @@ GstElement *GstreamerFrameCapture::get_encoder_plugin(const GstreamerEncoderSett
     }
 
     encoder = factory ? gst_element_factory_create(factory, "encoder") : nullptr;
-    if (encoder) { // Invalid properties will be ignored silently
-        /* x264enc properties */
-        gst_util_set_object_arg(G_OBJECT(encoder), "tune", "zerolatency");// stillimage, fastdecode, zerolatency
-        gst_util_set_object_arg(G_OBJECT(encoder), "bframes", "0");
-        gst_util_set_object_arg(G_OBJECT(encoder), "speed-preset", "1");// 1-ultrafast, 6-med, 9-veryslow
+    if (encoder) { // Set encoder properties
+        for (int i = 0; i < settings.prop_pairs.size(); i++) {
+            const char *prop_name = settings.prop_pairs[i].first.c_str();
+            if (!g_object_class_find_property(G_OBJECT_GET_CLASS(encoder), prop_name)) {
+                gst_syslog(LOG_WARNING, "'%s' property was not found for this encoder", prop_name);
+                continue;
+            }
+            const char *prop_val = settings.prop_pairs[i].second.c_str();
+            gst_syslog(LOG_NOTICE, "Trying to set encoder property: '%s = %s'", prop_name, prop_val);
+            /* Invalid properties will be ignored silently */
+            gst_util_set_object_arg(G_OBJECT(encoder), prop_name, prop_val);
+        }
     }
     gst_plugin_feature_list_free(filtered);
     gst_plugin_feature_list_free(encoders);
@@ -449,6 +457,16 @@ void GstreamerPlugin::ParseOptions(const ConfigureOption *options)
             }
         } else if (name == "gst.encoder") {
             settings.encoder = value;
+        } else if (name == "gst.prop") {
+            std::string prop_name, prop_val;
+            size_t pos = value.find('=');
+            if (!pos || pos >= value.size() - 1) {
+                gst_syslog(LOG_WARNING, "Property input is invalid ('%s' Ignored)", value.c_str());
+                continue;
+            }
+            prop_name = value.substr(0, pos);
+            prop_val = value.substr(pos + 1);
+            settings.prop_pairs.push_back(make_pair(prop_name, prop_val));
         }
     }
 }
-- 
2.21.0