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

[Snir Sheriber]

This allows to set plugin key=value properties on run time.
To add encoder plugin property use the following syntax:
-gst.prop="key=value"
Make sure syntax is accurate and that the property is supported by
the chosen plugin, wrong/invalid properties will be ignored silently.
Specific encoder available properties can be viewed by:
gst-inspect-1.0 <PLUGIN-NAME>
---
* This patch useful for encoders tuning and testing (later we can introduce
  fixed encoders setups), hence not checking for validity of input.
* I dropped sstream in previous patch but i found it useful here and added it
  again, alternative suggestions are welcome

---
 src/gst-plugin.cpp | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/gst-plugin.cpp b/src/gst-plugin.cpp
index 4e802f1..0d8773d 100644
--- a/src/gst-plugin.cpp
+++ b/src/gst-plugin.cpp
@@ -6,6 +6,7 @@
 
 #include <config.h>
 #include <cstring>
+#include <sstream>
 #include <exception>
 #include <stdexcept>
 #include <memory>
@@ -35,6 +36,7 @@ struct GstreamerEncoderSettings
     int fps = 25;
     SpiceVideoCodecType codec = SPICE_VIDEO_CODEC_TYPE_H264;
     std::string encoder;
+    std::vector<std::string> prop_strings;
 };
 
 template <typename T>
@@ -180,10 +182,15 @@ 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
+        const char *key;
+        const char *val;
+        for (int i = 1; i < settings.prop_strings.size(); i += 2) {
+            key = settings.prop_strings[i-1].c_str();
+            val = settings.prop_strings[i].c_str();
+            gst_util_set_object_arg(G_OBJECT(encoder), key, val);
+            gst_syslog(LOG_NOTICE, "Trying to set encoder property: '%s = %s'", key, val);
+        }
+
     }
     gst_plugin_feature_list_free(filtered);
     gst_plugin_feature_list_free(encoders);
@@ -449,6 +456,12 @@ void GstreamerPlugin::ParseOptions(const ConfigureOption *options)
             }
         } else if (name == "gst.encoder") {
             settings.encoder = value;
+        } else if (name == "gst.prop") {
+            std::stringstream ss(value);
+            std::string item;
+            while (std::getline(ss, item, '=')) {
+               settings.prop_strings.push_back(item);
+            }
         }
     }
 }
-- 
2.21.0