Enum CodecFactoryRequest

pub enum CodecFactoryRequest {
    GetDetailedCodecDescriptions {
        responder: CodecFactoryGetDetailedCodecDescriptionsResponder,
    },
    CreateDecoder {
        decoder_params: CreateDecoderParams,
        decoder: ServerEnd<StreamProcessorMarker>,
        control_handle: CodecFactoryControlHandle,
    },
    CreateEncoder {
        encoder_params: CreateEncoderParams,
        encoder: ServerEnd<StreamProcessorMarker>,
        control_handle: CodecFactoryControlHandle,
    },
    AttachLifetimeTracking {
        codec_end: EventPair,
        control_handle: CodecFactoryControlHandle,
    },
}

The purpose of the media::CodecFactory interface is to create media::StreamProcessor instances for decoders and encoders.

The interface methods don’t attempt to homogenize all codec types, preferring to have a separate dedicated message for decoders.

Variants

GetDetailedCodecDescriptions

A client should call |GetDetailedCodecDescriptions()| to get a list of codecs supported either by software implementations or by underlying hardware.

Fields

responder: CodecFactoryGetDetailedCodecDescriptionsResponder

CreateDecoder

CreateDecoder:

decoder_params - See CreateDecoder_Params comments for required and optional parameters for creating a decoder.

decoder - a Codec.NewRequest() which will hopefully be connected to a Codec server, or the Codec channel will get closed if no suitable codec can be found. We don’t return any additional Codec-specific status here because finding the Codec is allowed to be fully async, so we don’t necessarily yet know on return from this method which Codec will be selected, if any.

Rough sequence to create a decoder:

factory = ConnectToEnvironmentService(CodecFactory); CreateDecoder_Params params; [fill out params] CreateDecoder(params, decoder_request);

See use_media_decoder code for more detail.

Fields

decoder_params: CreateDecoderParams

decoder: ServerEnd<StreamProcessorMarker>

control_handle: CodecFactoryControlHandle

CreateEncoder

CreateEncoder:

encoder_params - See CreateEncoder_Params comments for required and optional parameters for creating a decoder.

encoder - a Codec.NewRequest() which will hopefully be connected to a Codec server, or the Codec channel will get closed if no suitable codec can be found. We don’t return any additional Codec-specific status here because finding the Codec is allowed to be fully async, so we don’t necessarily yet know on return from this method which Codec will be selected, if any.

Fields

encoder_params: CreateEncoderParams

encoder: ServerEnd<StreamProcessorMarker>

control_handle: CodecFactoryControlHandle

AttachLifetimeTracking

AttachLifetimeTracking:

Attach an eventpair endpoint to the next Create{X}(), so that the codec_end will be closed when the number of buffers allocated reaches ‘buffers_remaining’. Multiple eventpair endpoints can be attached per create, with an enforced limit of CODEC_FACTORY_LIFETIME_TRACKING_EVENTPAIR_PER_CREATE_MAX.

The lifetime signalled by this event is intended to track all resources used by the codec, including sysmem-allocated buffers created internally by the codec. The sysmem buffer collections visible to the client, for input and output buffers, are not included in the resources tracked here, because those can be tracked separately via fuchsia.sysmem.BufferCollection.AttachLifetimeTracking(). It is permitted to send a duplicate of codec_end to both this AttachLifetimeTracking() and also to fuchsia.sysmem.BufferCollection.AttachLifetimeTracking(). The ZX_EVENTPAIR_PEER_CLOSED will happen when both/all lifetimes are fully over. This conveniently avoids needing multiple separate async waits by the client.

In the case of server process crashes, or failure of a codec to plumb codec_end to sysmem, ZX_EVENTPAIR_PEER_CLOSED signalled on the peer of codec_end may occur shortly before all resources are freed.

A maximum of CODEC_FACTORY_LIFETIME_TRACKING_EVENTPAIR_PER_CREATE_MAX calls to AttachLifetimeTracking() are allowed before any Create{X}(). There is no way to cancel an attach short of closing the CodecFactory channel. Closing the client end of the eventpair doesn’t subtract from the number of pending attach(es). For this reason, it can be good to only send attach message(s) immediately before the relevant Create{X}(), when it’s known by the client that both the attach message(s) and the Create{X}() messages will be sent.

Closing the client’s end doesn’t result in any action by the server. If the server listens to events from the client end at all, it is for debug logging only.

The server intentionally doesn’t “trust” any bits signalled by the client. This mechanism intentionally uses only ZX_EVENTPAIR_PEER_CLOSED which can’t be triggered early, and is only triggered when all handles to codec_end are closed. No meaning is associated with any of the other signal bits, and clients should functionally ignore any other signal bits on either end of the eventpair or its peer.

The codec_end may lack ZX_RIGHT_SIGNAL or ZX_RIGHT_SIGNAL_PEER, but must have ZX_RIGHT_DUPLICATE (and must have ZX_RIGHT_TRANSFER to transfer without causing CodecFactory channel failure).

Fields

codec_end: EventPair

control_handle: CodecFactoryControlHandle

Implementations

impl CodecFactoryRequest

pub fn into_get_detailed_codec_descriptions( self, ) -> Option<CodecFactoryGetDetailedCodecDescriptionsResponder>

pub fn into_create_decoder( self, ) -> Option<(CreateDecoderParams, ServerEnd<StreamProcessorMarker>, CodecFactoryControlHandle)>

pub fn into_create_encoder( self, ) -> Option<(CreateEncoderParams, ServerEnd<StreamProcessorMarker>, CodecFactoryControlHandle)>

pub fn into_attach_lifetime_tracking( self, ) -> Option<(EventPair, CodecFactoryControlHandle)>

pub fn method_name(&self) -> &'static str

Name of the method defined in FIDL

Trait Implementations

impl Debug for CodecFactoryRequest

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.