[FFmpeg-devel] [PATCH] dxva: wait until D3D11 buffer copies are done before submitting them

[Steve Lhomme]

When used aggressively, calling SubmitDecoderBuffers() just after
ReleaseDecoderBuffer() may have the buffers not used properly and created
decoding artifacts.
It's likely due to the time to copy the submitted buffer in CPU mapped memory
to GPU memory. SubmitDecoderBuffers() doesn't appear to wait for the state
of the buffer submitted to become "ready".

For now it's not supported in the legacy API using AVD3D11VAContext, we need to
add a ID3D11DeviceContext in there as it cannot be derived from the other
interfaces we provide (ID3D11VideoContext is not a kind of ID3D11DeviceContext).
---
 libavcodec/dxva2.c          | 32 ++++++++++++++++++++++++++++++++
 libavcodec/dxva2_internal.h |  2 ++
 2 files changed, 34 insertions(+)

diff --git a/libavcodec/dxva2.c b/libavcodec/dxva2.c
index 32416112bf..dbbad8ed00 100644
--- a/libavcodec/dxva2.c
+++ b/libavcodec/dxva2.c
@@ -692,6 +692,12 @@ int ff_dxva2_decode_init(AVCodecContext *avctx)
         d3d11_ctx->surface       = sctx->d3d11_views;
         d3d11_ctx->workaround    = sctx->workaround;
         d3d11_ctx->context_mutex = INVALID_HANDLE_VALUE;
+
+        D3D11_QUERY_DESC query = { 0 };
+        query.Query = D3D11_QUERY_EVENT;
+        if (FAILED(ID3D11Device_CreateQuery(device_hwctx->device, &query,
+                                            (ID3D11Query**)&sctx->wait_copies)))
+            sctx->wait_copies = NULL;
     }
 #endif
 
@@ -729,6 +735,8 @@ int ff_dxva2_decode_uninit(AVCodecContext *avctx)
     av_buffer_unref(&sctx->decoder_ref);
 
 #if CONFIG_D3D11VA
+    if (sctx->wait_copies)
+        ID3D11Asynchronous_Release(sctx->wait_copies);
     for (i = 0; i < sctx->nb_d3d11_views; i++) {
         if (sctx->d3d11_views[i])
             ID3D11VideoDecoderOutputView_Release(sctx->d3d11_views[i]);
@@ -932,6 +940,13 @@ int ff_dxva2_common_end_frame(AVCodecContext *avctx, AVFrame *frame,
 
 #if CONFIG_D3D11VA
     if (ff_dxva2_is_d3d11(avctx)) {
+        if (sctx->wait_copies)
+        {
+            AVHWFramesContext *frames_ctx = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
+            AVD3D11VADeviceContext *device_hwctx = frames_ctx->device_ctx->hwctx;
+            ID3D11DeviceContext_Begin(device_hwctx->device_context, sctx->wait_copies);
+        }
+
         buffer = &buffer11[buffer_count];
         type = D3D11_VIDEO_DECODER_BUFFER_PICTURE_PARAMETERS;
     }
@@ -1005,9 +1020,26 @@ int ff_dxva2_common_end_frame(AVCodecContext *avctx, AVFrame *frame,
 
 #if CONFIG_D3D11VA
     if (ff_dxva2_is_d3d11(avctx))
+    {
+        int maxWait = 10;
+        /* wait until all the buffer release is done copying data to the GPU
+         * before doing the submit command */
+        if (sctx->wait_copies)
+        {
+            AVHWFramesContext *frames_ctx = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
+            AVD3D11VADeviceContext *device_hwctx = frames_ctx->device_ctx->hwctx;
+            ID3D11DeviceContext_End(device_hwctx->device_context, sctx->wait_copies);
+
+            while (maxWait-- && S_FALSE ==
+                   ID3D11DeviceContext_GetData(device_hwctx->device_context,
+                                               sctx->wait_copies, NULL, 0, 0))
+                SleepEx(2, TRUE);
+        }
+
         hr = ID3D11VideoContext_SubmitDecoderBuffers(D3D11VA_CONTEXT(ctx)->video_context,
                                                      D3D11VA_CONTEXT(ctx)->decoder,
                                                      buffer_count, buffer11);
+    }
 #endif
 #if CONFIG_DXVA2
     if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD) {
diff --git a/libavcodec/dxva2_internal.h b/libavcodec/dxva2_internal.h
index b822af59cd..c44e8e09b0 100644
--- a/libavcodec/dxva2_internal.h
+++ b/libavcodec/dxva2_internal.h
@@ -81,6 +81,8 @@ typedef struct FFDXVASharedContext {
     ID3D11VideoDecoderOutputView  **d3d11_views;
     int                          nb_d3d11_views;
     ID3D11Texture2D                *d3d11_texture;
+
+    ID3D11Asynchronous             *wait_copies;
 #endif
 
 #if CONFIG_DXVA2
-- 
2.26.2