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 custom source format (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.