video: Add `configure_video_stream_decoder` to the `VideoBackend` trait

video/external/src/backend.rs

@@ -63,6 +63,24 @@ impl VideoBackend for ExternalVideoBackend {
         Ok(self.streams.insert(proxy_or_stream))
     }
 
+    fn configure_video_stream_decoder(
+        &mut self,
+        stream: VideoStreamHandle,
+        configuration_data: &[u8],
+    ) -> Result<(), Error> {
+        let stream = self
+            .streams
+            .get_mut(stream)
+            .ok_or(Error::VideoStreamIsNotRegistered)?;
+
+        match stream {
+            ProxyOrStream::Proxied(handle) => self
+                .software
+                .configure_video_stream_decoder(*handle, configuration_data),
+            ProxyOrStream::Owned(stream) => stream.decoder.configure_decoder(configuration_data),
+        }
+    }
+
     fn preload_video_stream_frame(
         &mut self,
         stream: VideoStreamHandle,

video/software/src/backend.rs

@@ -66,6 +66,15 @@ impl VideoBackend for SoftwareVideoBackend {
         stream.decoder.preload_frame(encoded_frame)
     }
 
+    fn configure_video_stream_decoder(
+        &mut self,
+        _stream: VideoStreamHandle,
+        _configuration_data: &[u8],
+    ) -> Result<(), Error> {
+        // None of the software decoders require configuration.
+        Ok(())
+    }
+
     fn decode_video_stream_frame(
         &mut self,
         stream: VideoStreamHandle,

video/software/src/decoder.rs

@@ -13,6 +13,11 @@ pub mod screen;
 /// Trait for video decoders.
 /// This should be implemented for each video codec.
 pub trait VideoDecoder {
+    /// Configure the decoder.
+    fn configure_decoder(&mut self, _configuration_data: &[u8]) -> Result<(), Error> {
+        Ok(())
+    }
+
     /// Preload a frame.
     ///
     /// No decoding is intended to happen at this point in time. Instead, the

video/src/backend.rs

@@ -26,6 +26,15 @@ pub trait VideoBackend {
         filter: VideoDeblocking,
     ) -> Result<VideoStreamHandle, Error>;
 
+    /// Configure the decoder of a given video stream.
+    ///
+    /// The `configuration_data` contains codec-specific parameters.
+    fn configure_video_stream_decoder(
+        &mut self,
+        stream: VideoStreamHandle,
+        configuration_data: &[u8],
+    ) -> Result<(), Error>;
+
     /// Preload a frame of a given video stream.
     ///
     /// No decoding is intended to happen at this point in time. Instead, the

video/src/null.rs

@@ -44,6 +44,14 @@ impl VideoBackend for NullVideoBackend {
         Ok(self.streams.insert(()))
     }
 
+    fn configure_video_stream_decoder(
+        &mut self,
+        _stream: VideoStreamHandle,
+        _configuration_data: &[u8],
+    ) -> Result<(), Error> {
+        Ok(())
+    }
+
     fn preload_video_stream_frame(
         &mut self,
         _stream: VideoStreamHandle,