[FFmpeg-devel] [PATCH v2] avcodec/cuviddec: update parser ulMaxNumDecodeSurfaces

[Random Joe]

Fixes video output stutter caused by different number of buffers in
decoder vs parser introduced in 402d98c.

Signed-off-by: Random Joe <ff.random.joe at gmail.com>
---
  libavcodec/cuviddec.c | 13 +++++++++++--
  1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/libavcodec/cuviddec.c b/libavcodec/cuviddec.c
index 814bc53f70..1b62832eca 100644
--- a/libavcodec/cuviddec.c
+++ b/libavcodec/cuviddec.c
@@ -360,7 +360,14 @@ static int CUDAAPI cuvid_handle_video_sequence(void *opaque, CUVIDEOFORMAT* form
          }
      }
  
-    return 1;
+    // make CUVIDDECODECREATEINFO::ulNumDecodeSurfaces = CUVIDPARSERPARAMS::ulMaxNumDecodeSurfaces
+    // returning a value > 1  , will notify the driver to set the parser ulMaxNumDecodeSurfaces
+    // to this return value .
+
+    if(ctx->cuparseinfo.ulMaxNumDecodeSurfaces != cuinfo.ulNumDecodeSurfaces)
+        return cuinfo.ulNumDecodeSurfaces;
+    else
+        return 1;
  }
  
  static int CUDAAPI cuvid_handle_picture_decode(void *opaque, CUVIDPICPARAMS* picparams)
@@ -1022,7 +1029,9 @@ static av_cold int cuvid_decode_init(AVCodecContext *avctx)
          goto error;
      }
  
-    ctx->cuparseinfo.ulMaxNumDecodeSurfaces = ctx->nb_surfaces;
+    // set ulMaxNumDecodeSurfaces to a dummy value of 1 as recommended in NVDEC Programming Guide
+    // set the optimal value in pfnSequenceCallback where CUVIDEOFORMAT::min_num_decode_surfaces is reported
+    ctx->cuparseinfo.ulMaxNumDecodeSurfaces = 1;
      ctx->cuparseinfo.ulMaxDisplayDelay = (avctx->flags & AV_CODEC_FLAG_LOW_DELAY) ? 0 : CUVID_MAX_DISPLAY_DELAY;
      ctx->cuparseinfo.pUserData = avctx;
      ctx->cuparseinfo.pfnSequenceCallback = cuvid_handle_video_sequence;
-- 
2.39.2