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

[Uri Lublin]

On 7/16/19 1:55 PM, Snir Sheriber wrote:
> This allows to set plugin key=value properties on run time.
> To add encoder plugin property use the following syntax:
> -gst.prop="key=value"

Is this the correct syntax, or do you need a -c ?

> 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);

If gst_util_set_object_arg returns something it would be nice to add
a status to the gst_syslog


> +        }
> +
>       }
>       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);

Maybe better to get pairs.

Uri.

> +            }
>           }
>       }
>   }
>