mp4client man page

MP4Client — GPAC MPEG-4 command-line Player


MP4Client [options] [file]


MP4Client is GPAC command-line player. It supports all GPAC playback features (2D and 3D support, local playback, RTP streaming, HTTP faststart, many audio and video codecs ...). MP4Client also supports visual extraction to BMP, RAW or AVI (no compression, no audio).

Startup Options

-c file

specifies config file to use. Default config file is located in user home directory and created if not found.

-rti file

logs run-time information to file. Information logged is: FPS, CPU, Memory usage.


removes script message, buffering and downloading status.


exits after the first error is reported.

-log-file FILE

specifies where to write logs. Default is stdout. Same as -lf.

-logs TOOLS

sets log tools and levels, formatted as a ':'-separated list of toolX[:toolZ]@level. By default all errors are logged. level can be one of quiet, error, warning, info or debug. tool can be:
core: libgpac core
coding: bitstream formats (audio, video, scene)
container: container formats (ISO File, MPEG-2 TS, AVI, ...)
network: network data exept RTP trafic
rtp: rtp trafic
author: authoring tools (hint, import, export)
sync: terminal sync layer
codec: terminal codec messages
parser: scene parsers (svg, xmt, bt) and other
media: terminal media object management
scene: scene graph and scene manager
script: scripting engine messages
interact: interaction engine (events, scripts, etc)
smil: SMIL timing engine
compose: composition engine (2D, 3D, etc)
mmio: Audio/Video HW I/O management
rti: various run-time stats
cache: HTTP cache subsystem
audio: Audio renderer and mixers
mem: GPAC memory tracker
module: GPAC modules debugging
mutex: mutex
none: no tool logged
all: all tools logged - other tools can be specified afterwards.

Playback Options

A file can be controled during playback by typing one of the following key at prompt.


connects to a new URL entered at prompt by user.


restarts the current presentation


plays/pauses the current presentation


step one frame ahead in the current presentation


seek into presentation. Seek percentage is entered at prompt


prints current timing of the main timeline of the presentation


prints world info of the current presentation


prints list of all GF_ObjectDescriptor used in current presentation.


prints information of a given OD. Object ID is entered at prompt.


prints all objects timing and buffering info.


prints all objects buffering and memory info.


dumps current presentation scene graph to file or stdout.


Turns stress mode on/off.


Changes current navigation mode if possible/allowed. When a Layer3D is selected, sets layer3D navigation if allowed.


Reset to last active viewpoint. When a layer3D is selected, resets layer3D viewpoint.


Reload MPEG-4 Client with GPAC 2D Renderer.


Reload MPEG-4 Client with GPAC 3D Renderer.


forces 4/3 Aspect Ratio.


forces 16/9 Aspect Ratio.


forces no aspect ratio (always fill screen).


forces original Aspect Ratio (default mode).


prints the list of available plugins.


prints some GPAC configuration info.


quits the application.


enables streaming cache.


stops streaming cache and record it.


stops streaming cache and discard it.


prints list of available commands.

Window Shortcuts

When MP4Client window has the focus, the following shortcuts are available

Alt + right

Seeks 5% ahead from current time.

Alt + left

Seeks 5% before the current time

Alt + up

Increases volume by 5%

Alt + down

Decreases volume by 5%


Resets navigation to last bound viewpoint/viewport

4, 5, 6, 7

Same as non-window values

ESCAPE , alt+return, doubleclick

Toggles fullscreen on/off.

ctrl + 'f'

Prints current rendering framerate.

ctrl + 'R'

Sends a redraw message (complete scene state recompute).

ctrl + 'P'


ctrl + 'S'

Step one frame ahead.

Configuration File

When launched for the first time, MP4Client will ask for a font directory and a cache directory.

Font Directory

Indicates the absolute path to a directory containing a TrueType font repository. In case this directory is not specified or does not contain valid TrueType fonts, text will be disabled.

Cache Directory

Indicates the absolute path to a directory with write access to store files retrieved through HTTP downloads. In case this directory is not specified or has no write access HTTP downloads won't work.

Visual Extraction Options

When used to dump a visual presentation, the client is no longer interactive. All GPAC features are supported during capture, except audio-related ones. The following options can be passed at prompt:

-bmp [times]

dumps the specified frames to BMP format. If no time is specified, capture is made at t=0s. time is given in millisecond, as an SMPTE time code or as HH:MM:SS:MS time code. You may specify several frame times by using a dash-separated list of times (eg, '0-10-15').

-raw [times]

dumps the specified frames to RAW format. If no time is specified, cpature is made at t=0s.

-avi start:end

dumps the specified segment to uncompressed AVI format.

-fps rate

specifies frame rate for AVI dumping. Default frame rate is 25.0.

-size WxH

specifies frame size for dumping. Default frame size is the scene size.


uses fill aspect ratio. By default, the scene aspect ratio is preserved when dumping.


show window while dumping the content. By default, the window is hidden during capture.


forces usage of 2D renderer. By default, MP4Client uses the renderer indicated in GPAC configuration file.


forces usage of 3D renderer. By default, MP4Client uses the renderer indicated in GPAC configuration file.


removes script message, buffering and downloading status.


GPAC Configuration File: ~/.gpacrc


Jean Le Feuvre <> - GPAC (c) 2000-2005 - ENST 2005-200X

See Also

GPAC(1), MP4Box(1)


March 2005 MP4Client GPAC