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Diffstat (limited to 'ui/vnc-encoding-tight.h')
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diff --git a/ui/vnc-encoding-tight.h b/ui/vnc-encoding-tight.h new file mode 100644 index 0000000000..9b0910c79a --- /dev/null +++ b/ui/vnc-encoding-tight.h @@ -0,0 +1,181 @@ +/* + * QEMU VNC display driver: tight encoding + * + * From libvncserver/rfb/rfbproto.h + * Copyright (C) 2005 Rohit Kumar, Johannes E. Schindelin + * Copyright (C) 2000-2002 Constantin Kaplinsky. All Rights Reserved. + * Copyright (C) 2000 Tridia Corporation. All Rights Reserved. + * Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved. + * + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#ifndef VNC_ENCODING_TIGHT_H +#define VNC_ENCODING_TIGHT_H + +/*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + * Tight Encoding. + * + *-- The first byte of each Tight-encoded rectangle is a "compression control + * byte". Its format is as follows (bit 0 is the least significant one): + * + * bit 0: if 1, then compression stream 0 should be reset; + * bit 1: if 1, then compression stream 1 should be reset; + * bit 2: if 1, then compression stream 2 should be reset; + * bit 3: if 1, then compression stream 3 should be reset; + * bits 7-4: if 1000 (0x08), then the compression type is "fill", + * if 1001 (0x09), then the compression type is "jpeg", + * if 0xxx, then the compression type is "basic", + * values greater than 1001 are not valid. + * + * If the compression type is "basic", then bits 6..4 of the + * compression control byte (those xxx in 0xxx) specify the following: + * + * bits 5-4: decimal representation is the index of a particular zlib + * stream which should be used for decompressing the data; + * bit 6: if 1, then a "filter id" byte is following this byte. + * + *-- The data that follows after the compression control byte described + * above depends on the compression type ("fill", "jpeg" or "basic"). + * + *-- If the compression type is "fill", then the only pixel value follows, in + * client pixel format (see NOTE 1). This value applies to all pixels of the + * rectangle. + * + *-- If the compression type is "jpeg", the following data stream looks like + * this: + * + * 1..3 bytes: data size (N) in compact representation; + * N bytes: JPEG image. + * + * Data size is compactly represented in one, two or three bytes, according + * to the following scheme: + * + * 0xxxxxxx (for values 0..127) + * 1xxxxxxx 0yyyyyyy (for values 128..16383) + * 1xxxxxxx 1yyyyyyy zzzzzzzz (for values 16384..4194303) + * + * Here each character denotes one bit, xxxxxxx are the least significant 7 + * bits of the value (bits 0-6), yyyyyyy are bits 7-13, and zzzzzzzz are the + * most significant 8 bits (bits 14-21). For example, decimal value 10000 + * should be represented as two bytes: binary 10010000 01001110, or + * hexadecimal 90 4E. + * + *-- If the compression type is "basic" and bit 6 of the compression control + * byte was set to 1, then the next (second) byte specifies "filter id" which + * tells the decoder what filter type was used by the encoder to pre-process + * pixel data before the compression. The "filter id" byte can be one of the + * following: + * + * 0: no filter ("copy" filter); + * 1: "palette" filter; + * 2: "gradient" filter. + * + *-- If bit 6 of the compression control byte is set to 0 (no "filter id" + * byte), or if the filter id is 0, then raw pixel values in the client + * format (see NOTE 1) will be compressed. See below details on the + * compression. + * + *-- The "gradient" filter pre-processes pixel data with a simple algorithm + * which converts each color component to a difference between a "predicted" + * intensity and the actual intensity. Such a technique does not affect + * uncompressed data size, but helps to compress photo-like images better. + * Pseudo-code for converting intensities to differences is the following: + * + * P[i,j] := V[i-1,j] + V[i,j-1] - V[i-1,j-1]; + * if (P[i,j] < 0) then P[i,j] := 0; + * if (P[i,j] > MAX) then P[i,j] := MAX; + * D[i,j] := V[i,j] - P[i,j]; + * + * Here V[i,j] is the intensity of a color component for a pixel at + * coordinates (i,j). MAX is the maximum value of intensity for a color + * component. + * + *-- The "palette" filter converts true-color pixel data to indexed colors + * and a palette which can consist of 2..256 colors. If the number of colors + * is 2, then each pixel is encoded in 1 bit, otherwise 8 bits is used to + * encode one pixel. 1-bit encoding is performed such way that the most + * significant bits correspond to the leftmost pixels, and each raw of pixels + * is aligned to the byte boundary. When "palette" filter is used, the + * palette is sent before the pixel data. The palette begins with an unsigned + * byte which value is the number of colors in the palette minus 1 (i.e. 1 + * means 2 colors, 255 means 256 colors in the palette). Then follows the + * palette itself which consist of pixel values in client pixel format (see + * NOTE 1). + * + *-- The pixel data is compressed using the zlib library. But if the data + * size after applying the filter but before the compression is less then 12, + * then the data is sent as is, uncompressed. Four separate zlib streams + * (0..3) can be used and the decoder should read the actual stream id from + * the compression control byte (see NOTE 2). + * + * If the compression is not used, then the pixel data is sent as is, + * otherwise the data stream looks like this: + * + * 1..3 bytes: data size (N) in compact representation; + * N bytes: zlib-compressed data. + * + * Data size is compactly represented in one, two or three bytes, just like + * in the "jpeg" compression method (see above). + * + *-- NOTE 1. If the color depth is 24, and all three color components are + * 8-bit wide, then one pixel in Tight encoding is always represented by + * three bytes, where the first byte is red component, the second byte is + * green component, and the third byte is blue component of the pixel color + * value. This applies to colors in palettes as well. + * + *-- NOTE 2. The decoder must reset compression streams' states before + * decoding the rectangle, if some of bits 0,1,2,3 in the compression control + * byte are set to 1. Note that the decoder must reset zlib streams even if + * the compression type is "fill" or "jpeg". + * + *-- NOTE 3. The "gradient" filter and "jpeg" compression may be used only + * when bits-per-pixel value is either 16 or 32, not 8. + * + *-- NOTE 4. The width of any Tight-encoded rectangle cannot exceed 2048 + * pixels. If a rectangle is wider, it must be split into several rectangles + * and each one should be encoded separately. + * + */ + +#define VNC_TIGHT_EXPLICIT_FILTER 0x04 +#define VNC_TIGHT_FILL 0x08 +#define VNC_TIGHT_JPEG 0x09 +#define VNC_TIGHT_MAX_SUBENCODING 0x09 + +/* Filters to improve compression efficiency */ +#define VNC_TIGHT_FILTER_COPY 0x00 +#define VNC_TIGHT_FILTER_PALETTE 0x01 +#define VNC_TIGHT_FILTER_GRADIENT 0x02 + +/* Note: The following constant should not be changed. */ +#define VNC_TIGHT_MIN_TO_COMPRESS 12 + +/* The parameters below may be adjusted. */ +#define VNC_TIGHT_MIN_SPLIT_RECT_SIZE 4096 +#define VNC_TIGHT_MIN_SOLID_SUBRECT_SIZE 2048 +#define VNC_TIGHT_MAX_SPLIT_TILE_SIZE 16 + +#define VNC_TIGHT_JPEG_MIN_RECT_SIZE 4096 +#define VNC_TIGHT_DETECT_SUBROW_WIDTH 7 +#define VNC_TIGHT_DETECT_MIN_WIDTH 8 +#define VNC_TIGHT_DETECT_MIN_HEIGHT 8 + +#endif /* VNC_ENCODING_TIGHT_H */ |