lavc/vaapi_encode_h264: add "coder" option support

Follow libx264 style to support "coder" option, and set it to
cabac by default.

Signed-off-by: Yi A Wang <yi.a.wang@intel.com>
Signed-off-by: Jun Zhao <jun.zhao@intel.com>
Reviewed-by: Steven Liu <lingjiujianke@gmail.com>
Signed-off-by: Mark Thompson <sw@jkqxz.net>

libavcodec/vaapi_encode_h264.c

@@ -160,6 +160,8 @@ typedef struct VAAPIEncodeH264Options {
     int qp;
     int quality;
     int low_power;
+    // Entropy encoder type.
+    int coder;
 } VAAPIEncodeH264Options;
 
 
@@ -775,6 +777,8 @@ static int vaapi_encode_h264_init_sequence_params(AVCodecContext *avctx)
     VAEncPictureParameterBufferH264   *vpic = ctx->codec_picture_params;
     VAAPIEncodeH264Context            *priv = ctx->priv_data;
     VAAPIEncodeH264MiscSequenceParams *mseq = &priv->misc_sequence_params;
+    VAAPIEncodeH264Options             *opt =
+        (VAAPIEncodeH264Options*)ctx->codec_options_data;
     int i;
 
     {
@@ -920,7 +924,7 @@ static int vaapi_encode_h264_init_sequence_params(AVCodecContext *avctx)
         vpic->num_ref_idx_l1_active_minus1 = 0;
 
         vpic->pic_fields.bits.entropy_coding_mode_flag =
-            ((avctx->profile & 0xff) != 66);
+            opt->coder ? ((avctx->profile & 0xff) != 66) : 0;
         vpic->pic_fields.bits.weighted_pred_flag = 0;
         vpic->pic_fields.bits.weighted_bipred_idc = 0;
         vpic->pic_fields.bits.transform_8x8_mode_flag =
@@ -1262,6 +1266,12 @@ static const AVOption vaapi_encode_h264_options[] = {
     { "low_power", "Use low-power encoding mode (experimental: only supported "
       "on some platforms, does not support all features)",
       OFFSET(low_power), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, FLAGS },
+    { "coder", "Entropy coder type",
+      OFFSET(coder), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, FLAGS, "coder" },
+        { "cavlc", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, FLAGS, "coder" },
+        { "cabac", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, INT_MIN, INT_MAX, FLAGS, "coder" },
+        { "vlc",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, FLAGS, "coder" },
+        { "ac",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, INT_MIN, INT_MAX, FLAGS, "coder" },
     { NULL },
 };