MPEG-4 Scene Encoding Options¶
General considerations¶
MP4Box supports encoding and decoding of of BT, XMT, VRML and (partially) X3D formats int MPEG-4 BIFS, and encoding and decoding of XSR and SVG into MPEG-4 LASeR
Any media track specified through a MuxInfo element will be imported in the resulting MP4 file.
See https://wiki.gpac.io/Howtos/scenecoding/MPEG-4-BIFS-Textual-Format and related pages.
Scene Random Access¶
MP4Box can encode BIFS or LASeR streams and insert random access points at a given frequency. This is useful when packaging content for broadcast, where users will not turn in the scene at the same time. In MPEG-4 terminology, this is called the scene carousel.## BIFS Chunk Processing
The BIFS chunk encoding mode allows encoding single BIFS access units from an initial context and a set of commands.
The generated AUs are raw BIFS (not SL-packetized), in files called FILE-ESID-AUIDX.bifs, with FILE the basename of the input file.
Commands with a timing of 0 in the input will modify the carousel version only (i.e. output context).
Commands with a timing different from 0 in the input will generate new AUs.
Options:
-mp4: specify input file is for BIFS/LASeR encoding
-def: encode DEF names in BIFS
-sync (int): force BIFS sync sample generation every given time in ms (cannot be used with -shadow or -carousel )
-shadow (int): force BIFS sync shadow sample generation every given time in ms (cannot be used with -sync or -carousel )
-sclog: generate scene codec log file if available
-ms (string): import tracks from the given file
-ctx-in (string): specify initial context (MP4/BT/XMT) file for chunk processing. Input file must be a commands-only file
-ctx-out (string): specify storage of updated context (MP4/BT/XMT) file for chunk processing, optional
-resolution (int): resolution factor (-8 to 7, default 0) for LASeR encoding, and all coordinates are multiplied by 2^res before truncation (LASeR encoding)
-coord-bits (int): number of bits used for encoding truncated coordinates (0 to 31, default 12) (LASeR encoding)
-scale-bits (int): extra bits used for encoding truncated scales (0 to 4, default 0) (LASeR encoding)
-auto-quant (int): resolution is given as if using -resolution but coord-bits and scale-bits are inferred (LASeR encoding)
-global-quant (int): resolution is given as if using -resolution but the res is inferred (BIFS encoding)
Live Scene Encoder Options¶
The options shall be specified as opt_name=opt_val.
Options:
-live: enable live BIFS/LASeR encoder
-dst (string): destination IP
-port (int, default: 7000): destination port
-mtu (int, default: 1450): path MTU for RTP packets
-ifce (string): IP address of the physical interface to use
-ttl (int, default: 1): time to live for multicast packets
-sdp (string, default: session.sdp): output SDP file
-dims: turn on DIMS mode for SVG input
-no-rap: disable RAP sending and carousel generation
-src (string): source of scene updates
-rap (int): duration in ms of base carousel; you can specify the RAP period of a single ESID (not in DIMS) using ESID=X:time
Runtime options:
- q: quits
- u: inputs some commands to be sent
- U: same as u but signals the updates as critical
- e: inputs some commands to be sent without being aggregated
- E: same as e but signals the updates as critical
- f: forces RAP sending
- F: forces RAP regeneration and sending
- p: dumps current scene
SWF Importer Options¶
MP4Box can import simple Macromedia Flash files (".SWF")
You can specify a SWF input file with '-bt', '-xmt' and '-mp4' options
Options:
-global: all SWF defines are placed in first scene replace rather than when needed
-no-ctrl: use a single stream for movie control and dictionary (this will disable ActionScript)
-no-text: remove all SWF text
-no-font: remove all embedded SWF Fonts (local playback host fonts used)
-no-line: remove all lines from SWF shapes
-no-grad: remove all gradients from swf shapes
-quad: use quadratic bezier curves instead of cubic ones
-xlp: support for lines transparency and scalability
-ic2d: use indexed curve 2D hardcoded proto
-same-app: appearance nodes are reused
-flatten (number): complementary angle below which 2 lines are merged, value 0 means no flattening