Trait devices::virtio::video::decoder::backend::DecoderSession

source · 
pub trait DecoderSession {
    // Required methods
    fn set_output_parameters(
        &mut self,
        buffer_count: usize,
        format: Format
    ) -> Result<(), VideoError>;
    fn decode(
        &mut self,
        resource_id: u32,
        timestamp: u64,
        resource: GuestResourceHandle,
        offset: u32,
        bytes_used: u32
    ) -> Result<(), VideoError>;
    fn flush(&mut self) -> Result<(), VideoError>;
    fn reset(&mut self) -> Result<(), VideoError>;
    fn clear_output_buffers(&mut self) -> Result<(), VideoError>;
    fn event_pipe(&self) -> &dyn AsRawDescriptor;
    fn use_output_buffer(
        &mut self,
        picture_buffer_id: i32,
        resource: GuestResource
    ) -> Result<(), VideoError>;
    fn reuse_output_buffer(
        &mut self,
        picture_buffer_id: i32
    ) -> Result<(), VideoError>;
    fn read_event(&mut self) -> Result<DecoderEvent, VideoError>;
}
Expand description

Contains the device’s state for one playback session, i.e. one stream.

Required Methods§

source

fn set_output_parameters( &mut self, buffer_count: usize, format: Format ) -> Result<(), VideoError>

Tell how many output buffers will be used for this session and which format they will carry. This method must be called after a ProvidePictureBuffers event is emitted, and before the first call to use_output_buffer().

source

fn decode( &mut self, resource_id: u32, timestamp: u64, resource: GuestResourceHandle, offset: u32, bytes_used: u32 ) -> Result<(), VideoError>

Decode the compressed stream contained in [offset..offset+bytes_used] of the shared memory in the input resource.

resource_id is the ID of the input resource. It will be signaled using the NotifyEndOfBitstreamBuffer once the input resource is not used anymore.

timestamp is a timestamp that will be copied into the frames decoded from that input stream. Units are effectively free and provided by the input stream.

The device takes ownership of resource and is responsible for closing it once it is not used anymore.

The device will emit a NotifyEndOfBitstreamBuffer event with the resource_id value after the input buffer has been entirely processed.

The device will emit a PictureReady event with the timestamp value for each picture produced from that input buffer.

source

fn flush(&mut self) -> Result<(), VideoError>

Flush the decoder device, i.e. finish processing all queued decode requests and emit frames for them.

The device will emit a FlushCompleted event once the flush is done.

source

fn reset(&mut self) -> Result<(), VideoError>

Reset the decoder device, i.e. cancel all pending decoding requests.

The device will emit a ResetCompleted event once the reset is done.

source

fn clear_output_buffers(&mut self) -> Result<(), VideoError>

Immediately release all buffers passed using use_output_buffer() and reuse_output_buffer().

source

fn event_pipe(&self) -> &dyn AsRawDescriptor

Returns the event pipe on which the availability of events will be signaled. Note that the returned value is borrowed and only valid as long as the session is alive.

source

fn use_output_buffer( &mut self, picture_buffer_id: i32, resource: GuestResource ) -> Result<(), VideoError>

Ask the device to use resource to store decoded frames according to its layout. picture_buffer_id is the ID of the picture that will be reproduced in PictureReady events using this buffer.

The device takes ownership of resource and is responsible for closing it once the buffer is not used anymore (either when the session is closed, or a new set of buffers is provided for the session).

The device will emit a PictureReady event with the picture_buffer_id field set to the same value as the argument of the same name when a frame has been decoded into that buffer.

source

fn reuse_output_buffer( &mut self, picture_buffer_id: i32 ) -> Result<(), VideoError>

Ask the device to reuse an output buffer previously passed to use_output_buffer and that has previously been returned to the decoder in a PictureReady event.

The device will emit a PictureReady event with the picture_buffer_id field set to the same value as the argument of the same name when a frame has been decoded into that buffer.

source

fn read_event(&mut self) -> Result<DecoderEvent, VideoError>

Blocking call to read a single event from the event pipe.

Implementors§