avcodec/nvenc: added support for rate control lookahead

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

libavcodec/nvenc.c

@@ -328,6 +328,12 @@ static int nvenc_check_capabilities(AVCodecContext *avctx)
         return AVERROR(ENOSYS);
     }
 
+    ret = nvenc_check_cap(avctx, NV_ENC_CAPS_SUPPORT_LOOKAHEAD);
+    if (ctx->rc_lookahead > 0 && ret <= 0) {
+        av_log(avctx, AV_LOG_VERBOSE, "RC lookahead not supported\n");
+        return AVERROR(ENOSYS);
+    }
+
     return 0;
 }
 
@@ -687,6 +693,11 @@ static av_cold void nvenc_setup_rate_control(AVCodecContext *avctx)
     } else if (ctx->encode_config.rcParams.averageBitRate > 0) {
         ctx->encode_config.rcParams.vbvBufferSize = 2 * ctx->encode_config.rcParams.averageBitRate;
     }
+
+    if (ctx->rc_lookahead > 0) {
+        ctx->encode_config.rcParams.enableLookahead = 1;
+        ctx->encode_config.rcParams.lookaheadDepth = FFMIN(ctx->rc_lookahead, 32);
+    }
 }
 
 static av_cold int nvenc_setup_h264_config(AVCodecContext *avctx)

libavcodec/nvenc.h

@@ -179,6 +179,7 @@ typedef struct NvencContext
     int device;
     int flags;
     int async_depth;
+    int rc_lookahead;
 } NvencContext;
 
 int ff_nvenc_encode_init(AVCodecContext *avctx);

libavcodec/nvenc_h264.c

@@ -76,6 +76,7 @@ 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" },
+    { "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 },
     { "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 },

libavcodec/nvenc_hevc.c

@@ -74,6 +74,7 @@ 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" },
+    { "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 },
     { "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 },