Video Recording

Headless H.264 video recording via EGL offscreen rendering and ffmpeg. More...

Classes
struct	mj_kdl::VideoRecorder

Enumerations
enum class	mj_kdl::VideoResolution {   mj_kdl::VideoResolution::R360p = 360 , mj_kdl::VideoResolution::R480p = 480 , mj_kdl::VideoResolution::R720p = 720 , mj_kdl::VideoResolution::R1080p = 1080 ,   mj_kdl::VideoResolution::R2K = 1440 , mj_kdl::VideoResolution::R4K = 2160 }

Functions
bool	mj_kdl::init_video_recorder (VideoRecorder *vr, mjModel *model, const char *out_path, int width=1280, int height=720, int fps=60)
bool	mj_kdl::init_video_recorder (VideoRecorder *vr, mjModel *model, const char *out_path, VideoResolution resolution, int fps=60)
bool	mj_kdl::record_frame (VideoRecorder *vr, mjModel *model, mjData *data)
void	mj_kdl::cleanup (VideoRecorder *vr)

Detailed Description

Headless H.264 video recording via EGL offscreen rendering and ffmpeg.

No display or GLFW window is needed. Requires EGL (libegl-dev) and ffmpeg in PATH. Enable with -DBUILD_RECORDER=ON (default).

Enumeration Type Documentation

VideoResolution

enum class mj_kdl::VideoResolution

strong

Standard output resolution presets for init_video_recorder(). Each maps to a 16:9 frame size at the named quality level.

Enumerator
R360p
R480p
R720p
R1080p
R2K
R4K

Definition at line 239 of file mj_kdl_wrapper.hpp.

Function Documentation

cleanup()

void mj_kdl::cleanup

(

VideoRecorder *

vr

)

Flush the ffmpeg pipe, finalise the MP4, and release all EGL resources. After this call vr->_impl is null and the VideoRecorder may be discarded.

Parameters

vr	VideoRecorder to tear down.

init_video_recorder() [1/2]

bool mj_kdl::init_video_recorder	(	VideoRecorder *	vr,
		mjModel *	model,
		const char *	out_path,
		int	width = 1280,
		int	height = 720,
		int	fps = 60
	)

Initialise a headless EGL video recorder. Creates an EGL context, an offscreen render target, and launches an ffmpeg process (H.264/MP4) via a pipe. The MuJoCo model is used to size the scene and initialise the rendering context; it must remain valid until cleanup().

Parameters

vr	VideoRecorder to initialise; freed by cleanup(VideoRecorder*).
model	MuJoCo model for the rendering context.
out_path	Output MP4 path (e.g. "sim.mp4").
width	Frame width in pixels (default 1280).
height	Frame height in pixels (default 720).
fps	Playback frame rate (default 60).

Returns

true on success; false if EGL init or ffmpeg launch fails.

Referenced by main().

init_video_recorder() [2/2]

bool mj_kdl::init_video_recorder	(	VideoRecorder *	vr,
		mjModel *	model,
		const char *	out_path,
		VideoResolution	resolution,
		int	fps = 60
	)

Convenience overload: initialise a VideoRecorder using a named resolution preset. Frame width is derived from the preset at 16:9 aspect ratio.

Parameters

vr	VideoRecorder to initialise.
model	MuJoCo model.
out_path	Output MP4 path.
resolution	VideoResolution preset (e.g. VideoResolution::R1080p).
fps	Playback frame rate (default 60).

Returns

true on success.

record_frame()

bool mj_kdl::record_frame	(	VideoRecorder *	vr,
		mjModel *	model,
		mjData *	data
	)

Render the current simulation state and write one frame to the video stream. Call mj_step() (or equivalent) before each record_frame() call.

Parameters

vr	VideoRecorder initialised by init_video_recorder().
model	MuJoCo model.
data	MuJoCo data (current state).

Returns

true on success; false on render or pipe write error.

Referenced by main().