promeki::SDLPlayerMediaIO Class Reference

MediaIO sink that plays frames through SDL via FrameSync. More...

#include <sdlplayer.h>

Inheritance diagram for promeki::SDLPlayerMediaIO:

Collaboration diagram for promeki::SDLPlayerMediaIO:

Public Types
using	UPtr = UniquePtr< SDLPlayerMediaIO >
	Unique-ownership pointer to an SDLPlayerMediaIO.

Public Member Functions
SDLPlayerWidget *	widget () const
	Returns the widget that owns this task.
SDLAudioOutput *	audioOutput () const
	Returns the configured audio output.
bool	useAudioClock () const
	True when the audio device drives timing.
void	pause ()
	Pauses playback.
void	resume ()
	Resumes playback after a pause.
void	togglePause ()
	Convenience: calls pause or resume.
bool	isPaused () const
	Returns true when the playback clock is paused.
Error	describe (MediaIODescription *out) const override
Error	proposeInput (const MediaDesc &offered, MediaDesc *preferred) const override
void	cancelBlockingWork () override

Protected Member Functions
Error	executeCmd (MediaIOCommandOpen &cmd) override
Error	executeCmd (MediaIOCommandClose &cmd) override
Error	executeCmd (MediaIOCommandWrite &cmd) override

Friends
class	SDLPlayerWidget

Detailed Description

MediaIO sink that plays frames through SDL via FrameSync.

SDLPlayerMediaIO is a write-only MediaIO sink that consumes Frame objects via MediaIO::writeFrame(). It is always owned by an SDLPlayerWidget which provides both the render target and the user-facing controls (play/pause, focus routing, etc.) — clients should construct an SDLPlayerWidget rather than instantiating the backend directly.

Architecture

• The strand worker does not pace per frame. executeCmd(Write) decodes compressed images and hands the frame to a FrameSync instance, then returns.
• A dedicated pull thread drives FrameSync::pullFrame in a loop. The clock (SDL audio or wall) blocks the pull thread until each destination deadline; the output frame is then delivered to the SDLPlayerWidget for display and, if configured, to the SDLAudioOutput.
• Back-pressure comes from FrameSync's input queue running in FrameSync::InputOverflowPolicy::Block mode.
• Audio drift correction is real — the audio clock's rate ratio feeds FrameSync's audio resampler.

Thread Safety

Conditionally thread-safe. The dedicated worker thread, pull thread, and SDL event thread each touch a different subset of state, coordinated via FrameSync (lock-free queue), atomics on the clock state, and the SDL event-thread bounce for widget calls. Clients interact with the backend via the owning MediaIO sink, which marshals writeFrame() calls onto the worker — clients themselves may call from any thread.

Member Function Documentation

pause()

void promeki::SDLPlayerMediaIO::pause

(

)

Pauses playback.

Pauses the playback clock (which stops SDL audio consumption via SDLAudioClock::onPause) and tears down the pull thread so it isn't blocked on the clock. Safe to call from any thread; no-ops when no MediaIO is open or playback is already paused.

resume()

void promeki::SDLPlayerMediaIO::resume

(

)

Resumes playback after a pause.

Unpauses the clock and spawns a fresh pull thread. The base Clock's paused-offset accumulator rolls the deadline forward so the next output frame lands where it would have without the pause. No-op when no MediaIO is open or playback is not paused.

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The documentation for this class was generated from the following file:

• include/promeki/sdl/sdlplayer.h