I263
- FOURCCs: I263
- Company: Intel
General description
This codec is based on early drafts of the H.263 standard specification. It supports the following modes: Unrestricted Motion Vector mode, Advanced Prediction mode, PB frames mode, Improved PB frames mode (old version!) and Deblocking Filter mode.
Picture Layer
Data for each picture consists of a picture header followed by data for Group of Blocks, eventually followed by an end-of-sequence code and stuffing bits.
Picture Header
The Picture Header of the I.263 has the following format:
- Picture Start Code (PSC) (22 bits)
PSC is a word of 22 bits. Its value is 0000 0000 0000 0000 1 00000. All picture start codes shall be byte aligned.
- Temporal Reference (TR) (8 bits)
An 8-bit number which can have 256 possible values. It is formed by incrementing its value in the previously transmitted picture header by one plus the number of non-transmitted pictures (at 29.97 Hz) since the previously transmitted one. The arithmetic is performed with only the eight LSBs. In the optional PB-frames mode, TR only addresses P-pictures; for the temporal reference for B-pictures refer to section 5.1.7.
- Marker (1 bit)
This bit should be always set to "1" in order to avoid start code emulation.
- H.263 ID (1 bit)
This bit should be always set to "0" for distinction with H.261.
- Split screen indicator (1 bit)
This indicator is not used in the I.263. Just skip this bit.
- Document camera indicator (1 bit)
This indicator is not used in the I.263. Just skip this bit.
- Freeze Picture Release (1 bit)
Unused. Just skip this bit.
- Source Format (3 bits)
Indicates the source format of the picture. Values "000" and "110" are forbidden. "111" indicates the extended PTYPE (see below).
- Picture type (1 bit)
Picture Coding Type: “0” INTRA (I-picture), “1” INTER (P-picture).
- Unrestricted Motion Vector mode indicator (1 bit)
Unrestricted Motion Vector mode: “0” off, “1” on.
- Syntax-based Arithmetic Coding mode (SAC) indicator (1 bit)
Syntax-based Arithmetic Coding mode is not supported in the I.263. Just skip this bit.
- Advanced Prediction mode indicator (1 bit)
Advanced Prediction mode: “0” off, “1” on.
- PB-frames mode indicator (1 bit)
PB-frames mode: “0” normal I- or P-picture, “1” PB-frame. If the Picture Type bit (see above) is set to “0”, this bit shall be set to “0” as well.
Extended PTYPE (EPTYPE):
- Source Format (3 bits)
Values "000" and "111" are forbidden. "110" indicates that the custom source format (CSFMT) extension is present (see below).
- Unknown flags (2 bits)
These bits should be always set to "0". They have no meaning. Just skip them.
- Deblocking Filter mode indicator (1 bit)
Deblocking Filter mode: “0” off, “1” on.
- Unknown flag (1 bit)
This bit should be always set to "0". It has no meaning. Just skip it.
- Improved PB-frames mode indicator (1 bit)
Improved PB-frames mode: “0” off, “1” on. For description of this mode see below.
- Unknown flags (5 bits)
These bits should be always set to "0". They have no meaning. Just skip them.
- Unknown Marker (5 bits)
The value of this bits should be always set to "00001".