Struct VirtioVideoAdapterSession

pub struct VirtioVideoAdapterSession<D: DecoderBackend> {

    id: u32,
    backend_session: Option<D::Session>,
    poller: WaitContext<u32>,
    backend: Arc<Mutex<D>>,
    input_format: Format,
    output_format: Format,
    coded_size: (u32, u32),
    stream_params: StreamParams,
    initial_drc_received: bool,
    need_set_output_params: bool,
    pending_output_buffers: Vec<(u32, Option<GuestResource>)>,
    eos_capture_buffer: EosBuffer,
    num_output_buffers: usize,
}

Fields

id: u32

Session ID.

backend_session: Option<D::Session>

The backend session can only be created once we know the input format.

poller: WaitContext<u32>

Proxy poller. We need this because this backend creates the actual session with a delay, but the device needs the session FD as soon as it is created.

backend: Arc<Mutex<D>>

Shared reference to the device backend. Required so we can create the session lazily.

input_format: Format

output_format: Format

coded_size: (u32, u32)

Coded size currently set for the CAPTURE buffers.

stream_params: StreamParams

Stream parameters, as obtained from the stream itself.

initial_drc_received: bool

Whether the initial DRC event has been received. The backend will ignore CAPTURE buffers queued before that.

need_set_output_params: bool

Whether the set_output_parameters of the backend needs to be called before a CAPTURE buffer is sent.

pending_output_buffers: Vec<(u32, Option<GuestResource>)>

Indices of CAPTURE buffers that are queued but not send to the backend.

eos_capture_buffer: EosBuffer

Index of the capture buffer we kept in order to signal EOS.

num_output_buffers: usize

Number of output buffers that have been allocated, as reported by the decoder device.

This is required to call set_output_parameters on the virtio-video session.

Implementations

impl<D: DecoderBackend> VirtioVideoAdapterSession<D>

fn get_or_create_session(&mut self) -> IoctlResult<&mut D::Session>

Get the currently existing backend session if it exists, or create it using the current input format if it doesn’t.

fn try_send_pending_output_buffers(&mut self) -> IoctlResult<()>

Trait Implementations

impl<D: DecoderBackend> VideoDecoderBackendSession for VirtioVideoAdapterSession<D>

type BufferStorage = VirtioVideoAdapterBuffer

fn current_format(&self, direction: QueueDirection) -> V4l2MplaneFormat

Returns the current format set for the given direction, in a form suitable as a reply to VIDIOC_G_FMT.

fn stream_params(&self) -> StreamParams

Returns the stream parameters as read from the input.

fn drain(&mut self) -> IoctlResult<()>

Start draining the decoder pipeline for all buffers still in it.

fn clear_output_buffers(&mut self) -> IoctlResult<()>

Remove any output buffer that has been previously added using [use_as_output].

fn next_event(&mut self) -> Option<VideoDecoderBackendEvent>

Returns the next pending event if there is one, or None if there aren’t any.

fn buffers_allocated(&mut self, direction: QueueDirection, num_buffers: u32)

Called whenever the decoder device has allocated buffers for a given queue.

fn poll_fd(&self) -> Option<BorrowedFd<'_>>

Returns a file descriptor that signals POLLIN whenever an event is pending and can be read using [next_event], or None if the backend does not support this.

fn decode( &mut self, input: &Self::BufferStorage, index: u32, timestamp: timeval, bytes_used: u32, ) -> IoctlResult<()>

Decode the encoded stream in input, of length bytes_used, which corresponds to OUTPUT buffer index.

fn use_as_output( &mut self, index: u32, backing: &mut Self::BufferStorage, ) -> IoctlResult<()>

Use backing as the backing storage for output buffer index.

fn streaming_state(&mut self, _direction: QueueDirection, _streaming: bool)

Optional hook called whenever the streaming state of a queue changes. Some backends may need this information to operate properly.

fn resume(&mut self)

Optional hook called by the decoder to signal it has processed a pausing event sent by the backend.