libs: encoder: h264: Add uncompliant mode reducing coded buffer size

Added a new property "compliance-mode", which default is the normal
strict compliant mode.

The second mode, "restrict-buf-alloc", is to limit the coded buffer
allocation size to improve performance in some specific Intel
platforms (there is asignificant performance improvement in parallel
encodings). Under this new mode, we use the MinCR field in A.3.1 for
pre-calculating the coded-buffer size.

https://bugzilla.gnome.org/show_bug.cgi?id=784590

2 files changed, 71 insertions, 0 deletions

diff --git a/gst-libs/gst/vaapi/gstvaapiencoder_h264.c b/gst-libs/gst/vaapi/gstvaapiencoder_h264.c
index 601a4be2..a3824124 100644
--- a/gst-libs/gst/vaapi/gstvaapiencoder_h264.c
+++ b/gst-libs/gst/vaapi/gstvaapiencoder_h264.c
@@ -76,6 +76,37 @@
 #define GST_H264_NAL_REF_IDC_MEDIUM      2
 #define GST_H264_NAL_REF_IDC_HIGH        3
 
+typedef enum
+{
+  GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_STRICT = 0,
+  GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_RESTRICT_CODED_BUFFER_ALLOC = 1,
+} GstVaapiEnoderH264ComplianceMode;
+
+static GType
+gst_vaapi_encoder_h264_compliance_mode_type (void)
+{
+  static GType gtype = 0;
+
+  if (gtype == 0) {
+    static const GEnumValue values[] = {
+      {GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_STRICT,
+            "Strict compliance to the H264 Specification ",
+          "strict"},
+      /* The main intention is to reduce the CodedBuffer Size allocation.
+       * This will help to get better performance in some of the Intel
+       * platforms which has LLC restirictions */
+      {GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_RESTRICT_CODED_BUFFER_ALLOC,
+            "Restict the allocation size of coded-buffer",
+          "restrict-buf-alloc"},
+      {0, NULL, NULL},
+    };
+
+    gtype =
+        g_enum_register_static ("GstVaapiEncoderH264ComplianceMode", values);
+  }
+  return gtype;
+}
+
 /* only for internal usage, values won't be equal to actual payload type */
 typedef enum
 {
@@ -717,6 +748,10 @@ struct _GstVaapiEncoderH264
   GstVaapiH264ViewReorderPool reorder_pools[MAX_NUM_VIEWS];
 
   gboolean use_aud;
+
+  /* Complance mode */
+  GstVaapiEnoderH264ComplianceMode compliance_mode;
+  guint min_cr;                 // Minimum Compression Ratio (A.3.1)
 };
 
 /* Write a SEI buffering period payload */
@@ -1140,6 +1175,7 @@ ensure_level (GstVaapiEncoderH264 * encoder)
 
   encoder->level = limits_table[i].level;
   encoder->level_idc = limits_table[i].level_idc;
+  encoder->min_cr = limits_table[i].MinCR;
   return TRUE;
 
   /* ERRORS */
@@ -2880,6 +2916,17 @@ set_context_info (GstVaapiEncoder * base_encoder)
   /* Account for slice header */
   base_encoder->codedbuf_size += encoder->num_slices * (4 +
       GST_ROUND_UP_8 (MAX_SLICE_HDR_SIZE) / 8);
+  /* Some of the Intel Platforms(eg: APL) doesn't have LLC so
+   * the driver call cflush to ensure data consistency which is an
+   * expensive operation but we can still reduce the impact by
+   * limitting the pre-calculated coded_buffer size. This is not
+   * strictly following the h264 specification, but should be safe
+   * enough with intel-vaapi-driver. Our test cases showing significat
+   * performance improvement on APL platfrom with small coded-buffer size */
+  if (encoder->compliance_mode ==
+      GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_RESTRICT_CODED_BUFFER_ALLOC)
+    base_encoder->codedbuf_size /= encoder->min_cr;
+
 
   base_encoder->context_info.entrypoint = encoder->entrypoint;
 
@@ -2959,6 +3006,9 @@ gst_vaapi_encoder_h264_init (GstVaapiEncoder * base_encoder)
     ref_pool->max_reflist1_count = 1;
   }
 
+  encoder->compliance_mode = GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_STRICT;
+  encoder->min_cr = 1;
+
   return TRUE;
 }
 
@@ -3051,6 +3101,10 @@ gst_vaapi_encoder_h264_set_property (GstVaapiEncoder * base_encoder,
     case GST_VAAPI_ENCODER_H264_PROP_AUD:
       encoder->use_aud = g_value_get_boolean (value);
       break;
+    case GST_VAAPI_ENCODER_H264_PROP_COMPLIANCE_MODE:
+      encoder->compliance_mode = g_value_get_enum (value);
+      break;
+
     default:
       return GST_VAAPI_ENCODER_STATUS_ERROR_INVALID_PARAMETER;
   }
@@ -3228,6 +3282,21 @@ gst_vaapi_encoder_h264_get_default_properties (void)
           "Use AU (Access Unit) delimeter", FALSE,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
+  /**
+   * GstVaapiEncoderH264:Compliance Mode:
+   *
+   * Encode Tuning(Tweaking) with different compliance modes .
+   *
+   *
+   */
+  GST_VAAPI_ENCODER_PROPERTIES_APPEND (props,
+      GST_VAAPI_ENCODER_H264_PROP_COMPLIANCE_MODE,
+      g_param_spec_enum ("compliance-mode",
+          "Spec Compliance Mode",
+          "Tune Encode quality/performance by relaxing specification compliance restrictions",
+          gst_vaapi_encoder_h264_compliance_mode_type (),
+          GST_VAAPI_ENCODER_H264_COMPLIANCE_MODE_STRICT, G_PARAM_READWRITE));
+
   return props;
 }
 
diff --git a/gst-libs/gst/vaapi/gstvaapiencoder_h264.h b/gst-libs/gst/vaapi/gstvaapiencoder_h264.h
index 5019b6cf..dec2ea97 100644
--- a/gst-libs/gst/vaapi/gstvaapiencoder_h264.h
+++ b/gst-libs/gst/vaapi/gstvaapiencoder_h264.h
@@ -48,6 +48,7 @@ typedef struct _GstVaapiEncoderH264 GstVaapiEncoderH264;
  *   in milliseconds (uint).
  * @GST_VAAPI_ENCODER_H264_PROP_NUM_VIEWS: Number of views per frame.
  * @GST_VAAPI_ENCODER_H264_PROP_VIEW_IDS: View IDs
+ * @GST_VAAPI_ENCODER_H264_PROP_COMPLIANCE_MODE: Relax Compliance restrictions
  *
  * The set of H.264 encoder specific configurable properties.
  */
@@ -62,6 +63,7 @@ typedef enum {
   GST_VAAPI_ENCODER_H264_PROP_NUM_VIEWS = -8,
   GST_VAAPI_ENCODER_H264_PROP_VIEW_IDS = -9,
   GST_VAAPI_ENCODER_H264_PROP_AUD = -10,
+  GST_VAAPI_ENCODER_H264_PROP_COMPLIANCE_MODE = -11,
 } GstVaapiEncoderH264Prop;
 
 GstVaapiEncoder *