From 67bb11b5f6548c3b273b575f44077db19bb9a98e Mon Sep 17 00:00:00 2001
From: Philip Langdale <philipl@overt.org>
Date: Sat, 5 Dec 2020 20:25:29 -0800
Subject: [PATCH] avcodec/nvdec: Add support for decoding monochrome av1

The nvidia hardware explicitly supports decoding monochrome content,
presumably for the AVIF alpha channel. Supporting this requires an
adjustment in av1dec and explicit monochrome detection in nvdec.

I'm not sure why the monochrome path in av1dec did what it did - it
seems non-functional - YUV440P doesn't seem a logical pix_fmt for
monochrome and conditioning on chroma sub-sampling doesn't make sense.
So I changed it.

I've tested 8bit content, but I haven't found a way to create a 10bit
sample, so that path is untested for now.
---
 libavcodec/av1dec.c  | 19 ++++++++++++++++---
 libavcodec/nvdec.c   |  3 +++
 libavcodec/version.h |  2 +-
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
index d7b2ac9d46..bc897af9cf 100644
--- a/libavcodec/av1dec.c
+++ b/libavcodec/av1dec.c
@@ -387,9 +387,12 @@ static int get_pixel_format(AVCodecContext *avctx)
                 av_log(avctx, AV_LOG_WARNING, "Unknown AV1 pixel format.\n");
         }
     } else {
-        if (seq->color_config.subsampling_x == 1 &&
-            seq->color_config.subsampling_y == 1)
-            pix_fmt = AV_PIX_FMT_YUV440P;
+        if (bit_depth == 8)
+            pix_fmt = AV_PIX_FMT_GRAY8;
+        else if (bit_depth == 10)
+            pix_fmt = AV_PIX_FMT_GRAY10;
+        else if (bit_depth == 12)
+            pix_fmt = AV_PIX_FMT_GRAY12;
         else
             av_log(avctx, AV_LOG_WARNING, "Unknown AV1 pixel format.\n");
     }
@@ -430,6 +433,16 @@ static int get_pixel_format(AVCodecContext *avctx)
 #endif
 #if CONFIG_AV1_VAAPI_HWACCEL
         *fmtp++ = AV_PIX_FMT_VAAPI;
+#endif
+        break;
+    case AV_PIX_FMT_GRAY8:
+#if CONFIG_AV1_NVDEC_HWACCEL
+        *fmtp++ = AV_PIX_FMT_CUDA;
+#endif
+        break;
+    case AV_PIX_FMT_GRAY10:
+#if CONFIG_AV1_NVDEC_HWACCEL
+        *fmtp++ = AV_PIX_FMT_CUDA;
 #endif
         break;
     }
diff --git a/libavcodec/nvdec.c b/libavcodec/nvdec.c
index 48281293ce..23c84d9acf 100644
--- a/libavcodec/nvdec.c
+++ b/libavcodec/nvdec.c
@@ -83,6 +83,9 @@ static int map_chroma_format(enum AVPixelFormat pix_fmt)
 {
     int shift_h = 0, shift_v = 0;
 
+    if (av_pix_fmt_count_planes(pix_fmt) == 1)
+        return cudaVideoChromaFormat_Monochrome;
+
     av_pix_fmt_get_chroma_sub_sample(pix_fmt, &shift_h, &shift_v);
 
     if (shift_h == 1 && shift_v == 1)
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 4ee221b7f2..1c10d105f6 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -29,7 +29,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR  58
 #define LIBAVCODEC_VERSION_MINOR 115
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \