hw_base_encode: Support refs option to limit number of references

Set default value to 0 to keep the old behavior of using maximum number
of references.

libavcodec/d3d12va_encode_hevc.c

@@ -762,6 +762,7 @@ static const FFCodecDefault d3d12va_encode_hevc_defaults[] = {
     { "b_qoffset",      "0"   },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/hw_base_encode.c

@@ -666,6 +666,11 @@ int ff_hw_base_init_gop_structure(FFHWBaseEncodeContext *ctx, AVCodecContext *av
     ctx->ref_l0 = FFMIN(ref_l0, MAX_PICTURE_REFERENCES);
     ctx->ref_l1 = FFMIN(ref_l1, MAX_PICTURE_REFERENCES);
 
+    if (avctx->refs > 0) {
+        ctx->ref_l0 = FFMIN(ctx->ref_l0, avctx->refs);
+        ctx->ref_l1 = FFMIN(ctx->ref_l1, avctx->refs);
+    }
+
     if (flags & FF_HW_FLAG_INTRA_ONLY || avctx->gop_size <= 1) {
         av_log(avctx, AV_LOG_VERBOSE, "Using intra frames only.\n");
         ctx->gop_size = 1;

libavcodec/vaapi_encode_av1.c

@@ -1027,6 +1027,7 @@ static const FFCodecDefault vaapi_encode_av1_defaults[] = {
     { "g",              "120" },
     { "qmin",           "1"   },
     { "qmax",           "255" },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vaapi_encode_h264.c

@@ -1153,6 +1153,7 @@ static const FFCodecDefault vaapi_encode_h264_defaults[] = {
     { "b_qoffset",      "0"   },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vaapi_encode_h265.c

@@ -1184,6 +1184,7 @@ static const FFCodecDefault vaapi_encode_h265_defaults[] = {
     { "b_qoffset",      "0"   },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vaapi_encode_vp8.c

@@ -235,6 +235,7 @@ static const FFCodecDefault vaapi_encode_vp8_defaults[] = {
     { "g",              "120" },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vaapi_encode_vp9.c

@@ -292,6 +292,7 @@ static const FFCodecDefault vaapi_encode_vp9_defaults[] = {
     { "g",              "250" },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vulkan_encode_av1.c

@@ -1367,6 +1367,7 @@ static const FFCodecDefault vulkan_encode_av1_defaults[] = {
     { "g",              "300" },
     { "qmin",           "1"   },
     { "qmax",           "255" },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vulkan_encode_h264.c

@@ -1634,6 +1634,7 @@ static const FFCodecDefault vulkan_encode_h264_defaults[] = {
     { "b_qoffset",      "0"   },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };
 

libavcodec/vulkan_encode_h265.c

@@ -1761,6 +1761,7 @@ static const FFCodecDefault vulkan_encode_h265_defaults[] = {
     { "b_qoffset",      "0"   },
     { "qmin",           "-1"  },
     { "qmax",           "-1"  },
+    { "refs",           "0"   },
     { NULL },
 };