[FFmpeg-devel] [PATCH] nvenc set slice number to 1 to improve encoding quality and clamp initial qp value to [1, 51]

[Agatha Hu]

---
 libavcodec/nvenc.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index 43b8e78..6365434 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -762,6 +762,17 @@ static av_cold int nvenc_encode_init(AVCodecContext *avctx)
         }
     }
 
+    switch (avctx->codec->id) {
+    case AV_CODEC_ID_H264:
+        ctx->encode_config.encodeCodecConfig.h264Config.sliceMode = 3;
+        ctx->encode_config.encodeCodecConfig.h264Config.sliceModeData = 1;
+        break;
+    case AV_CODEC_ID_H265:
+        ctx->encode_config.encodeCodecConfig.hevcConfig.sliceMode = 3;
+        ctx->encode_config.encodeCodecConfig.hevcConfig.sliceModeData = 1;
+        break;
+    }
+
     /* when there're b frames, set dts offset */
     if (ctx->encode_config.frameIntervalP >= 2)
         ctx->last_dts = -2;
@@ -843,10 +854,10 @@ static av_cold int nvenc_encode_init(AVCodecContext *avctx)
         ctx->encode_config.rcParams.initialRCQP.qpInterP  = qp_inter_p;
 
         if(avctx->i_quant_factor != 0.0 && avctx->b_quant_factor != 0.0) {
-            ctx->encode_config.rcParams.initialRCQP.qpIntra = qp_inter_p * fabs(avctx->i_quant_factor);
-            ctx->encode_config.rcParams.initialRCQP.qpIntra += avctx->i_quant_offset;
-            ctx->encode_config.rcParams.initialRCQP.qpInterB = qp_inter_p * fabs(avctx->b_quant_factor);
-            ctx->encode_config.rcParams.initialRCQP.qpInterB += avctx->b_quant_offset;
+            ctx->encode_config.rcParams.initialRCQP.qpIntra = av_clip(
+                qp_inter_p * fabs(avctx->i_quant_factor) + avctx->i_quant_offset, 0, 51);
+            ctx->encode_config.rcParams.initialRCQP.qpInterB = av_clip(
+                qp_inter_p * fabs(avctx->b_quant_factor) + avctx->b_quant_offset, 0, 51);
         } else {
             ctx->encode_config.rcParams.initialRCQP.qpIntra = qp_inter_p;
             ctx->encode_config.rcParams.initialRCQP.qpInterB = qp_inter_p;
-- 
1.9.5.github.0