[FFmpeg-devel] [PATCH] avcodec/av1_vaapi: add direct film grain mode

[Ruijing Dong]

Adding direct film grain mode for av1 decoder, which
outputs alongside film grain.

AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN is the new flag
introduced to enable this path.

issue:
By using AMD av1 decoder via VAAPI, when used with film
grain content, the output displays black screen with
incorrect frame order.

The issue being discussed in here:
https://gitlab.freedesktop.org/mesa/mesa/-/issues/6903#note_1613807

example:
This flag can be used in ffmpeg command:

ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128
      -hwaccel_flags 8
      -i input_with_film_gram.obu
      output_with_film_grain.yuv

Signed-off-by: Ruijing Dong <ruijing.dong at amd.com>
---
 libavcodec/avcodec.h   | 17 +++++++++++++++++
 libavcodec/vaapi_av1.c |  6 ++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 3edd8e2636..9420e7820d 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -2253,6 +2253,23 @@ typedef struct AVHWAccel {
  */
 #define AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH (1 << 2)
 
+/**
+ * The film grain synthesis could be seperate from decoding process.
+ * The downstream device would apply the film grain parameters seperately.
+ * The desired film grain parameters can be found in SEI section in H264
+ * or H265 bitstreams.
+ *
+ * In AV1, film grain is mandatorily specified, av1 decoders like AMD
+ * av1 decoder process film grain content internally, and the output
+ * includes applied film grain. For the purpose of supporting these av1
+ * decoders, this flag needs to be utilized.
+ *
+ * @warning If the stream has no film grain content, this flag will
+ *          be ignored in the supported av1 decoders. It is advised
+ *          that this flag should only be used in av1 decoders
+ *          that support it.
+ */
+#define AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN (1 << 3)
 /**
  * @}
  */
diff --git a/libavcodec/vaapi_av1.c b/libavcodec/vaapi_av1.c
index d0339b2705..6db910f2bf 100644
--- a/libavcodec/vaapi_av1.c
+++ b/libavcodec/vaapi_av1.c
@@ -127,6 +127,7 @@ static int vaapi_av1_start_frame(AVCodecContext *avctx,
     int8_t bit_depth_idx;
     int err = 0;
     int apply_grain = !(avctx->export_side_data & AV_CODEC_EXPORT_DATA_FILM_GRAIN) && film_grain->apply_grain;
+    int direct_film_grain = avctx->hwaccel_flags & AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN;
     uint8_t remap_lr_type[4] = {AV1_RESTORE_NONE, AV1_RESTORE_SWITCHABLE, AV1_RESTORE_WIENER, AV1_RESTORE_SGRPROJ};
     uint8_t segmentation_feature_signed[AV1_SEG_LVL_MAX] = {1, 1, 1, 1, 1, 0, 0, 0};
     uint8_t segmentation_feature_max[AV1_SEG_LVL_MAX] = {255, AV1_MAX_LOOP_FILTER,
@@ -136,7 +137,7 @@ static int vaapi_av1_start_frame(AVCodecContext *avctx,
     if (bit_depth_idx < 0)
         goto fail;
 
-    if (apply_grain) {
+    if (apply_grain && !direct_film_grain) {
         if (ctx->tmp_frame->buf[0])
             ff_thread_release_buffer(avctx, ctx->tmp_frame);
         err = ff_thread_get_buffer(avctx, ctx->tmp_frame, AV_GET_BUFFER_FLAG_REF);
@@ -375,6 +376,7 @@ static int vaapi_av1_end_frame(AVCodecContext *avctx)
     VAAPIAV1DecContext *ctx = avctx->internal->hwaccel_priv_data;
 
     int apply_grain = !(avctx->export_side_data & AV_CODEC_EXPORT_DATA_FILM_GRAIN) && film_grain->apply_grain;
+    int direct_film_grain = avctx->hwaccel_flags & AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN;
     int ret;
     ret = ff_vaapi_decode_issue(avctx, pic);
     if (ret < 0)
@@ -385,7 +387,7 @@ static int vaapi_av1_end_frame(AVCodecContext *avctx)
             if (ctx->ref_tab[i].frame->buf[0])
                 ff_thread_release_buffer(avctx, ctx->ref_tab[i].frame);
 
-            if (apply_grain) {
+            if (apply_grain && !direct_film_grain) {
                 ret = av_frame_ref(ctx->ref_tab[i].frame, ctx->tmp_frame);
                 if (ret < 0)
                     return ret;
-- 
2.25.1