vaapi: av1: submit slice parameters as an array

All tiles belonging to the same tile group must be submitted to the vaapi
driver as an array.

The Intel driver, in particular, expects one array of Slice Parameters per
instance of Slice Data when submitting the data for an AV1 Tile Group. It will
produce a corrupted frame if the slice parameters are submitted separately
(i.e.: in their own VABuffers).

This was discovered by Nicolas Dufresne.

Author: dwlsalmeida

src/decoder/stateless/av1/vaapi.rs

@@ -536,11 +536,12 @@ fn build_pic_param<M: SurfaceMemoryDescriptor>(
     ))
 }
 
-fn build_slice_params_for_tg(tg: &TileGroupObu) -> anyhow::Result<Vec<libva::BufferType>> {
-    let mut slice_params = vec![];
+fn build_slice_params_for_tg(tg: &TileGroupObu) -> anyhow::Result<libva::BufferType> {
+    let mut slice_params = libva::SliceParameterBufferAV1::new();
 
     for tile in &tg.tiles {
-        let slice_param = libva::SliceParameterBufferAV1::new(
+        /* all tiles must be submitted in the same slice parameter array */
+        slice_params.add_slice_parameter(
             tile.tile_size,
             tile.tile_offset,
             0,
@@ -551,13 +552,11 @@ fn build_slice_params_for_tg(tg: &TileGroupObu) -> anyhow::Result<Vec<libva::Buf
             0,
             0,
         );
-
-        slice_params.push(libva::BufferType::SliceParameter(
-            libva::SliceParameter::AV1(slice_param),
-        ));
     }
 
-    Ok(slice_params)
+    Ok(libva::BufferType::SliceParameter(
+        libva::SliceParameter::AV1(slice_params),
+    ))
 }
 
 fn build_slice_data_for_tg(tg: TileGroupObu) -> libva::BufferType {
@@ -652,13 +651,11 @@ impl<M: SurfaceMemoryDescriptor + 'static> StatelessAV1DecoderBackend for VaapiB
         let metadata = self.metadata_state.get_parsed()?;
         let context = &metadata.context;
 
-        for slice_param in slice_params {
-            let buffer = context
-                .create_buffer(slice_param)
-                .context("Failed to create slice parameter buffer")?;
+        let buffer = context
+            .create_buffer(slice_params)
+            .context("Failed to create slice parameter buffer")?;
 
-            picture.add_buffer(buffer)
-        }
+        picture.add_buffer(buffer);
 
         let buffer = context
             .create_buffer(slice_data)