vulkan_decode: clean up slice handling

Move the slice offsets buffer to the thread decode context.
It isn't part of the resources for frame decoding, the driver
has to process and finish with it at submission time.
That way, it doesn't need to be alloc'd + freed on every frame.

libavcodec/vulkan_decode.c

@@ -207,12 +207,12 @@ int ff_vk_decode_add_slice(AVCodecContext *avctx, FFVulkanDecodePicture *vp,
                       ctx->caps.minBitstreamBufferSizeAlignment;
     new_size = FFALIGN(new_size, ctx->caps.minBitstreamBufferSizeAlignment);
 
-    slice_off = av_fast_realloc(vp->slice_off, &vp->slice_off_max,
+    slice_off = av_fast_realloc(dec->slice_off, &dec->slice_off_max,
                                 (nb + 1)*sizeof(slice_off));
     if (!slice_off)
         return AVERROR(ENOMEM);
 
-    *offsets = vp->slice_off = slice_off;
+    *offsets = dec->slice_off = slice_off;
     slice_off[nb] = vp->slices_size;
 
     vkbuf = vp->slices_buf ? (FFVkVideoBuffer *)vp->slices_buf->data : NULL;
@@ -538,9 +538,6 @@ void ff_vk_decode_free_frame(AVHWDeviceContext *dev_ctx, FFVulkanDecodePicture *
     /* Free slices data */
     av_buffer_unref(&vp->slices_buf);
 
-    /* TODO: use a pool in the decode context instead to avoid per-frame allocs. */
-    av_freep(&vp->slice_off);
-
     /* Destroy image view (out) */
     if (vp->img_view_out && vp->img_view_out != vp->img_view_dest)
         destroy_image_view(hwctx->act_dev, vp->img_view_out, hwctx->alloc);
@@ -1035,6 +1032,7 @@ int ff_vk_decode_uninit(AVCodecContext *avctx)
     av_buffer_pool_uninit(&dec->tmp_pool);
     av_buffer_unref(&dec->session_params);
     av_buffer_unref(&dec->shared_ref);
+    av_freep(&dec->slice_off);
     return 0;
 }
 

libavcodec/vulkan_decode.h

@@ -66,6 +66,9 @@ typedef struct FFVulkanDecodeContext {
     AVBufferPool *tmp_pool; /* Pool for temporary data, if needed (HEVC) */
     size_t tmp_pool_ele_size;
     int params_changed;
+
+    uint32_t                       *slice_off;
+    unsigned int                    slice_off_max;
 } FFVulkanDecodeContext;
 
 typedef struct FFVulkanDecodePicture {
@@ -94,8 +97,6 @@ typedef struct FFVulkanDecodePicture {
     /* Slice data */
     AVBufferRef                    *slices_buf;
     size_t                          slices_size;
-    uint32_t                       *slice_off;
-    unsigned int                    slice_off_max;
 } FFVulkanDecodePicture;
 
 /**

libavcodec/vulkan_h264.c

@@ -463,7 +463,6 @@ static int vk_h264_start_frame(AVCodecContext          *avctx,
     hp->h264_pic_info = (VkVideoDecodeH264PictureInfoKHR) {
         .sType = VK_STRUCTURE_TYPE_VIDEO_DECODE_H264_PICTURE_INFO_KHR,
         .pStdPictureInfo = &hp->h264pic,
-        .sliceCount = 0,
     };
 
     vp->decode_info = (VkVideoDecodeInfoKHR) {

libavcodec/vulkan_hevc.c

@@ -855,7 +855,6 @@ static int vk_hevc_start_frame(AVCodecContext          *avctx,
         .sType = VK_STRUCTURE_TYPE_VIDEO_DECODE_H265_PICTURE_INFO_KHR,
         .pStdPictureInfo = &hp->h265pic,
         .sliceSegmentCount = 0,
-        .pSliceSegmentOffsets = vp->slice_off,
     };
 
     vp->decode_info = (VkVideoDecodeInfoKHR) {