Lower surfaces usage for nvenc encoding process

ffmpeg_surfaces.patch

diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index a3a2ef5..1691d15 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -1157,7 +1157,7 @@ static av_cold int nvenc_setup_surfaces(AVCodecContext *avctx)
     NvencContext *ctx = avctx->priv_data;
     int i, res;
     int num_mbs = ((avctx->width + 15) >> 4) * ((avctx->height + 15) >> 4);
-    ctx->nb_surfaces = FFMAX((num_mbs >= 8160) ? 32 : 48,
+    ctx->nb_surfaces = FFMAX((num_mbs >= 8160) ? 8 : 12,
                              ctx->nb_surfaces);
     ctx->async_depth = FFMIN(ctx->async_depth, ctx->nb_surfaces - 1);
 
diff --git a/libavcodec/nvenc_h264.c b/libavcodec/nvenc_h264.c
index 6914046b..7f050af 100644
--- a/libavcodec/nvenc_h264.c
+++ b/libavcodec/nvenc_h264.c
@@ -80,7 +80,7 @@ static const AVOption options[] = {
     { "vbr_2pass",    "Multi-pass variable bitrate mode",   0,                    AV_OPT_TYPE_CONST, { .i64 = NV_ENC_PARAMS_RC_2_PASS_VBR },           0, 0, VE, "rc" },
     { "rc-lookahead", "Number of frames to look ahead for rate-control",
                                                             OFFSET(rc_lookahead), AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX, VE },
-    { "surfaces",     "Number of concurrent surfaces",      OFFSET(nb_surfaces),  AV_OPT_TYPE_INT,   { .i64 = 32 },  0, INT_MAX, VE },
+    { "surfaces",     "Number of concurrent surfaces",      OFFSET(nb_surfaces),  AV_OPT_TYPE_INT,   { .i64 = 8 },  0, INT_MAX, VE },
     { "cbr",          "Use cbr encoding mode",              OFFSET(cbr),          AV_OPT_TYPE_BOOL,  { .i64 = 0 },   0, 1, VE },
     { "2pass",        "Use 2pass encoding mode",            OFFSET(twopass),      AV_OPT_TYPE_BOOL,  { .i64 = -1 }, -1, 1, VE },
     { "gpu",          "Selects which NVENC capable GPU to use. First GPU is 0, second is 1, and so on.",