[PATCH 2/2] gstreamer-encoder: Use a h/w based encoder with Intel GPUs if possible (v2)

[Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>]

Once it is determined that an Intel GPU is available/active (after
looking into udev's database), we try to see if there is a h/w
based encoder (element) available (in Gstreamer's registry cache)
for the user selected video codec. In other words, if we find that
the Intel Media SDK Gstreamer plugin (libgstmsdk.so) and associated
libraries (such as va or vaapi) are all installed properly, we add
the appropriate h/w based encoder and post-processor/converter
elements to the pipeline (along with any relevant options) instead
of the s/w based elements.

For example, if the user selects h264 as the preferred codec format,
msdkh264enc and vapostproc will be preferred instead of x264enc
and videoconvert.

v2: (addressed some review comments from Frediano)
- Moved the udev helper into spice-common
- Refactored the code to choose plugins in order msdk > va > vaapi

Cc: Frediano Ziglio <freddy77@xxxxxxxxx>
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>
Cc: Dongwon Kim <dongwon.kim@xxxxxxxxx>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Co-developed-by: Jin Chung Teng <jin.chung.teng@xxxxxxxxx>
Co-developed-by: Hazwan Arif Mazlan <hazwan.arif.mazlan@xxxxxxxxx>
---
 server/gstreamer-encoder.c | 96 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 93 insertions(+), 3 deletions(-)

diff --git a/server/gstreamer-encoder.c b/server/gstreamer-encoder.c
index 057509b5..44666f42 100644
--- a/server/gstreamer-encoder.c
+++ b/server/gstreamer-encoder.c
@@ -31,6 +31,7 @@
 #include "red-common.h"
 #include "video-encoder.h"
 #include "utils.h"
+#include "common/udev.h"
 
 
 #define SPICE_GST_DEFAULT_FPS 30
@@ -913,14 +914,94 @@ static const gchar* get_gst_codec_name(const SpiceGstEncoder *encoder)
     }
 }
 
+static const char video_codecs[][8] = {
+    { "" },
+    { "mjpeg" },
+    { "vp8" },
+    { "h264" },
+    { "vp9" },
+    { "h265" },
+};
+
+static bool gst_features_lookup(const gchar *feature_name)
+{
+    GstRegistry *registry;
+    GstPluginFeature *feature;
+
+    registry = gst_registry_get();
+    if (!registry) {
+        return false;
+    }
+
+    feature = gst_registry_lookup_feature(registry, feature_name);
+    if (!feature) {
+        return false;
+    }
+
+    gst_object_unref(feature);
+    return true;
+}
+
+static gchar *find_best_plugin(const gchar *codec_name)
+{
+    const char *plugins[3] = {"msdk", "va", "vaapi"};
+    gchar *feature_name;
+    int i;
+
+    for (i = 0; i < 3; i++) {
+        feature_name = !codec_name ? g_strconcat(plugins[i], "postproc", NULL) :
+                       g_strconcat(plugins[i], codec_name, "enc", NULL);
+        if (!gst_features_lookup(feature_name)) {
+            g_free(feature_name);
+            feature_name = NULL;
+            continue;
+        }
+        break;
+    }
+    return feature_name;
+}
+
+static void try_intel_hw_plugins(const gchar *codec_name, gchar **converter,
+                                 gchar **gstenc_name, gchar **gstenc_opts)
+{
+    gchar *encoder = find_best_plugin(codec_name);
+    if (!encoder) {
+        return;
+    }
+    gchar *vpp = find_best_plugin(NULL);
+    if (!vpp) {
+        return;
+    }
+
+    g_free(*converter);
+    g_free(*gstenc_name);
+    g_free(*gstenc_opts);
+
+    *gstenc_name = encoder;
+    if (strstr(encoder, "msdk")) {
+        *gstenc_opts = g_strdup("async-depth=1 rate-control=3 gop-size=1 tune=16 b-frames=0 target-usage=7 min-qp=15 max-qp=35");
+    } else if (strstr(encoder, "vaapi")) {
+        *gstenc_opts = g_strdup("rate-control=cqp max-bframes=0 min-qp=15 max-qp=35");
+    } else {
+        *gstenc_opts = g_strdup("rate-control=16 b-frames=0 target-usage=7 min-qp=15 max-qp=35");
+    }
+
+    if (strstr(vpp, "vaapi")) {
+        *converter = g_strconcat(vpp, " ! video/x-raw(memory:VASurface),format=NV12", NULL);
+    } else {
+        *converter = g_strconcat(vpp, " ! video/x-raw(memory:VAMemory),format=NV12", NULL);
+    }
+    g_free(vpp);
+}
+
 static gboolean create_pipeline(SpiceGstEncoder *encoder)
 {
 #ifdef HAVE_GSTREAMER_0_10
-    const gchar *converter = "ffmpegcolorspace";
+    gchar *converter = g_strdup("ffmpegcolorspace");
 #else
-    const gchar *converter = "videoconvert ! video/x-raw,format=NV12";
+    gchar *converter = g_strdup("videoconvert ! video/x-raw,format=NV12");
 #endif
-    const gchar* gstenc_name = get_gst_codec_name(encoder);
+    gchar* gstenc_name = g_strdup(get_gst_codec_name(encoder));
     if (!gstenc_name) {
         return FALSE;
     }
@@ -973,12 +1054,21 @@ static gboolean create_pipeline(SpiceGstEncoder *encoder)
         return FALSE;
     }
 
+    const char *codec_name = video_codecs[encoder->base.codec_type];
+    GpuVendor vendor = spice_udev_detect_gpu();
+    if (vendor == GPU_VENDOR_INTEL) {
+        try_intel_hw_plugins(codec_name, &converter, &gstenc_name,
+                             &gstenc_opts);
+    }
+
     GError *err = NULL;
     gchar *desc = g_strdup_printf("appsrc is-live=true format=time do-timestamp=true name=src !"
                                   " %s ! %s name=encoder %s ! appsink name=sink",
                                   converter, gstenc_name, gstenc_opts);
     spice_debug("GStreamer pipeline: %s", desc);
     encoder->pipeline = gst_parse_launch_full(desc, NULL, GST_PARSE_FLAG_FATAL_ERRORS, &err);
+    g_free(converter);
+    g_free(gstenc_name);
     g_free(gstenc_opts);
     g_free(desc);
     if (!encoder->pipeline || err) {
-- 
2.39.2