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.