Video Recording

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

Classes
struct	mj_kdl::CameraConf
class	mj_kdl::CameraRosPublisher
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
Status	mj_kdl::init_video_recorder (VideoRecorder *vr, mjModel *model, const char *out_path, int width=1280, int height=720, int fps=60)
Status	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, Env *env)
Status	mj_kdl::init_offscreen (VideoRecorder *vr, mjModel *model, int width, int height)
bool	mj_kdl::render_rgb (VideoRecorder *vr, Env *env, std::uint8_t *out)
bool	mj_kdl::render_rgb (VideoRecorder *vr, Env *env, std::function< void(const std::uint8_t *rgb)> done)
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 452 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_offscreen()

Status mj_kdl::init_offscreen	(	VideoRecorder *	vr,
		mjModel *	model,
		int	width,
		int	height )

Initialise offscreen rendering only: EGL context, no ffmpeg process and no output file. Use with render_rgb() to grab frames; the camera is vr->cam, as for a recording, and cleanup(VideoRecorder*) frees it. An open vr is freed first.

Parameters

vr	VideoRecorder to initialise; freed by cleanup(VideoRecorder*).
model	MuJoCo model whose default free camera vr->cam starts from.
width	Frame width in pixels.
height	Frame height in pixels.

Returns

an error if EGL init fails.

Referenced by TEST().

init_video_recorder() [1/2]

Status 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 and launches an ffmpeg process (H.264/MP4) via a pipe. The render context is made from the Env at its first frame and remade after the Env's model is rebuilt.

Parameters

vr	VideoRecorder to initialise; freed by cleanup(VideoRecorder*).
model	MuJoCo model whose default free camera vr->cam starts from.
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

an error if EGL init or ffmpeg launch fails.

Referenced by main(), and TEST().

init_video_recorder() [2/2]

Status 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

an empty Status on success, else the error.

record_frame()

bool mj_kdl::record_frame	(	VideoRecorder *	vr,
		Env *	env )

Snapshot env's current state as the next video frame; it is rendered and encoded on the recorder's thread. Waits only while the previous frame has not been picked up.

Parameters

vr	VideoRecorder initialised by init_video_recorder().
env	Env to render.

Returns

false once rendering or the pipe to ffmpeg has failed; every frame is recorded.

Referenced by main(), and TEST().

render_rgb() [1/2]

bool mj_kdl::render_rgb	(	VideoRecorder *	vr,
		Env *	env,
		std::function< void(const std::uint8_t *rgb)>	done )

Snapshot env's current state and return; done gets the top-down RGB8 frame on the recorder's thread, valid only during the call. Waits only while the previous frame has not been picked up.

Parameters

vr	VideoRecorder initialised by init_offscreen() or init_video_recorder().
env	Env to render.
done	Receives width*height*3 bytes.

Returns

false once rendering has failed.

render_rgb() [2/2]

bool mj_kdl::render_rgb	(	VideoRecorder *	vr,
		Env *	env,
		std::uint8_t *	out )

Render env's current state into a caller-owned top-down RGB8 buffer of width*height*3 bytes.

Parameters

vr	VideoRecorder initialised by init_offscreen() or init_video_recorder().
env	Env to render.
out	Destination buffer, width*height*3 bytes.

Returns

true on success.

Referenced by TEST().