nvenc: Minimize the surface allocation

The previous default sets the allocated surfaces to 32 unless it is
user-overridden or the lookahead parameter is set.

Change the surfaces calculation for default, B-frames and lookahead scenario.

libavcodec/nvenc.c

@@ -874,6 +874,44 @@ static int nvenc_setup_codec_config(AVCodecContext *avctx)
     return 0;
 }
 
+static int nvenc_recalc_surfaces(AVCodecContext *avctx)
+{
+    NVENCContext *ctx = avctx->priv_data;
+    // default minimum of 4 surfaces
+    // multiply by 2 for number of NVENCs on gpu (hardcode to 2)
+    // another multiply by 2 to avoid blocking next PBB group
+    int nb_surfaces = FFMAX(4, ctx->config.frameIntervalP * 2 * 2);
+
+    // lookahead enabled
+    if (ctx->rc_lookahead > 0) {
+        // +1 is to account for lkd_bound calculation later
+        // +4 is to allow sufficient pipelining with lookahead
+        nb_surfaces = FFMAX(1, FFMAX(nb_surfaces, ctx->rc_lookahead + ctx->config.frameIntervalP + 1 + 4));
+        if (nb_surfaces > ctx->nb_surfaces && ctx->nb_surfaces > 0) {
+            av_log(avctx, AV_LOG_WARNING,
+                "Defined rc_lookahead requires more surfaces, "
+                "increasing used surfaces %d -> %d\n",
+                ctx->nb_surfaces, nb_surfaces);
+        }
+        ctx->nb_surfaces = FFMAX(nb_surfaces, ctx->nb_surfaces);
+    } else {
+        if (ctx->config.frameIntervalP > 1 &&
+            ctx->nb_surfaces < nb_surfaces && ctx->nb_surfaces > 0) {
+            av_log(avctx, AV_LOG_WARNING,
+                "Defined b-frame requires more surfaces, "
+                "increasing used surfaces %d -> %d\n",
+                ctx->nb_surfaces, nb_surfaces);
+            ctx->nb_surfaces = FFMAX(ctx->nb_surfaces, nb_surfaces);
+        } else if (ctx->nb_surfaces <= 0)
+            ctx->nb_surfaces = nb_surfaces;
+        // otherwise use user specified value
+    }
+
+    ctx->nb_surfaces = FFMAX(1, FFMIN(MAX_REGISTERED_FRAMES, ctx->nb_surfaces));
+    ctx->async_depth = FFMIN(ctx->async_depth, ctx->nb_surfaces - 1);
+    return 0;
+}
+
 static int nvenc_setup_encoder(AVCodecContext *avctx)
 {
     NVENCContext *ctx               = avctx->priv_data;
@@ -956,6 +994,8 @@ static int nvenc_setup_encoder(AVCodecContext *avctx)
     ctx->initial_pts[0] = AV_NOPTS_VALUE;
     ctx->initial_pts[1] = AV_NOPTS_VALUE;
 
+    nvenc_recalc_surfaces(avctx);
+
     nvenc_setup_rate_control(avctx);
 
     if (avctx->flags & AV_CODEC_FLAG_INTERLACED_DCT) {
@@ -1057,11 +1097,6 @@ static int nvenc_setup_surfaces(AVCodecContext *avctx)
     NVENCContext *ctx = avctx->priv_data;
     int i, ret;
 
-    ctx->nb_surfaces = FFMAX(4 + avctx->max_b_frames,
-                             ctx->nb_surfaces);
-    ctx->async_depth = FFMIN(ctx->async_depth, ctx->nb_surfaces - 1);
-
-
     ctx->frames = av_mallocz_array(ctx->nb_surfaces, sizeof(*ctx->frames));
     if (!ctx->frames)
         return AVERROR(ENOMEM);

libavcodec/nvenc_h264.c

@@ -72,14 +72,14 @@ static const AVOption options[] = {
     { "ll_2pass_quality", "Multi-pass optimized for image quality (only for low-latency presets)",       0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_QUALITY },       0, 0, VE, "rc" },
     { "ll_2pass_size",    "Multi-pass optimized for constant frame size (only for low-latency presets)", 0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_FRAMESIZE_CAP }, 0, 0, VE, "rc" },
     { "vbr_2pass",        "Multi-pass variable bitrate mode",                                            0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_VBR },           0, 0, VE, "rc" },
-    { "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 = 0 },                    0, MAX_REGISTERED_FRAMES, VE },
     { "device",   "Select a specific NVENC device",       OFFSET(device),      AV_OPT_TYPE_INT,    { .i64 = -1 },                   -2, INT_MAX, VE, "device" },
     { "any",      "Pick the first device available",      0,                   AV_OPT_TYPE_CONST,  { .i64 = ANY_DEVICE },           0, 0, VE, "device" },
     { "list",     "List the available devices",           0,                   AV_OPT_TYPE_CONST,  { .i64 = LIST_DEVICES },         0, 0, VE, "device" },
     { "async_depth", "Delay frame output by the given amount of frames", OFFSET(async_depth), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, VE },
     { "delay",       "Delay frame output by the given amount of frames", OFFSET(async_depth), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, VE },
 #if NVENCAPI_MAJOR_VERSION >= 7
-    { "rc-lookahead", "Number of frames to look ahead for rate-control", OFFSET(rc_lookahead), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, VE },
+    { "rc-lookahead", "Number of frames to look ahead for rate-control", OFFSET(rc_lookahead), AV_OPT_TYPE_INT, { .i64 = 0 }, -1, INT_MAX, VE },
     { "no-scenecut", "When lookahead is enabled, set this to 1 to disable adaptive I-frame insertion at scene cuts", OFFSET(no_scenecut), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },
     { "b_adapt", "When lookahead is enabled, set this to 0 to disable adaptive B-frame decision", OFFSET(b_adapt), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, VE },
     { "spatial-aq", "set to 1 to enable Spatial AQ", OFFSET(aq), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },

libavcodec/nvenc_hevc.c

@@ -72,14 +72,14 @@ static const AVOption options[] = {
     { "ll_2pass_quality", "Multi-pass optimized for image quality (only for low-latency presets)",       0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_QUALITY },       0, 0, VE, "rc" },
     { "ll_2pass_size",    "Multi-pass optimized for constant frame size (only for low-latency presets)", 0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_FRAMESIZE_CAP }, 0, 0, VE, "rc" },
     { "vbr_2pass",        "Multi-pass variable bitrate mode",                                            0, AV_OPT_TYPE_CONST,  { .i64 = NV_ENC_PARAMS_RC_2_PASS_VBR },           0, 0, VE, "rc" },
-    { "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 = 0 },                    0, MAX_REGISTERED_FRAMES, VE },
     { "device",   "Select a specific NVENC device",       OFFSET(device),      AV_OPT_TYPE_INT,    { .i64 = -1 },                   -2, INT_MAX, VE, "device" },
     { "any",      "Pick the first device available",      0,                   AV_OPT_TYPE_CONST,  { .i64 = ANY_DEVICE },           0, 0, VE, "device" },
     { "list",     "List the available devices",           0,                   AV_OPT_TYPE_CONST,  { .i64 = LIST_DEVICES },         0, 0, VE, "device" },
     { "async_depth", "Delay frame output by the given amount of frames", OFFSET(async_depth), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, VE },
     { "delay",       "Delay frame output by the given amount of frames", OFFSET(async_depth), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, VE },
 #if NVENCAPI_MAJOR_VERSION >= 7
-    { "rc-lookahead", "Number of frames to look ahead for rate-control", OFFSET(rc_lookahead), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, VE },
+    { "rc-lookahead", "Number of frames to look ahead for rate-control", OFFSET(rc_lookahead), AV_OPT_TYPE_INT, { .i64 = 0 }, -1, INT_MAX, VE },
     { "no-scenecut", "When lookahead is enabled, set this to 1 to disable adaptive I-frame insertion at scene cuts", OFFSET(no_scenecut), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },
     { "spatial_aq", "set to 1 to enable Spatial AQ", OFFSET(aq), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },
     { "zerolatency", "Set 1 to indicate zero latency operation (no reordering delay)", OFFSET(zerolatency), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },