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2.2.2.2.4 TS_RFX_CONTEXT

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The TS_RFX_CONTEXT message contains information regarding the encoding properties being used.


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CodecChannelT

...

ctxId

tileSize

properties

...

CodecChannelT (8 bytes): A TS_RFX_CODEC_CHANNELT structure. The blockType field MUST be set to WBT_CONTEXT (0xCCC3).

ctxId (1 byte): An 8-bit unsigned integer. Specifies an identifier for this context message. This field MUST be set to 0x00. The decoder SHOULD ignore this field.

tileSize (2 bytes): A 16-bit unsigned integer. Specifies the tile size used by the RemoteFX codec. This field MUST be set to CT_TILE_64x64 (0x0040), indicating that a tile is 64 x 64 pixels.

properties (2 bytes): A 16-bit unsigned integer. Contains a collection of bit-packed property fields. The format of this field is described by the following bitfield diagram.


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flags

cct

xft

et

qt

r

flags (3 bits): A 3-bit unsigned integer. Specifies operational flags.

Flag

Meaning

CODEC_MODE

0x02

The codec is operating in image mode. If this flag is not set, the codec is operating in video mode.

When operating in image mode, the Encode Headers messages (section 2.2.2.2) MUST always precede an encoded frame. When operating in video mode, the header messages MUST be present at the beginning of the stream and MAY be present elsewhere.

cct (2 bits): A 2-bit unsigned integer. Specifies the color conversion transform. This field MUST be set to COL_CONV_ICT (0x1) to specify the transform defined by the equations in sections 3.1.8.1.3 and 3.1.8.2.5. The decoder SHOULD ignore this field.

xft (4 bits): A 4-bit unsigned integer. Specifies the DWT. This field MUST be set to CLW_XFORM_DWT_53_A (0x1), which indicates the DWT given by the equations in sections 3.1.8.1.4 and 3.1.8.2.4.

et (4 bits): A 4-bit unsigned integer. Specifies the entropy algorithm. This field MUST be set to one of the following values.

Value

Meaning

CLW_ENTROPY_RLGR1

0x01

RLGR algorithm as detailed in 3.1.8.1.7.1.

CLW_ENTROPY_RLGR3

0x04

RLGR algorithm as detailed in 3.1.8.1.7.2.

The decoder SHOULD ignore this value and use the value defined in the properties field of TS_RFX_TILESET (section 2.2.2.3.4).

qt (2 bits): A 2-bit unsigned integer. Specifies the quantization type. This field MUST be set to SCALAR_QUANTIZATION (0x1). The decoder SHOULD ignore this field.

r (1 bit): A 1-bit field reserved for future use. This field MUST be ignored when received.