This page is based on the codec description written by Konstantin Shishkov found in the document Description of the Apple Quicktime Animation (RLE) Format located at http://multimedia.cx/qtrle.txt.
- FOURCCs: qdrw
- Company: Apple
QDraw is another RLE format supported by the Quicktime multimedia system. It is identified by the FOURCC 'qdrw'. QDraw frames contain palettized 8-bit pixel data and transport their own palette data within frames.
All multi-byte numbers are encoded in big-endian format.
An encoded QDraw frame is laid out as follows:
bytes 0-103 unknown bytes 104-107 number of colors - 1 bytes 108.. color table (8 bytes per entry)
One color table entry is laid out as:
byte 0-1 index of palette table entry to replace byte 2-3 16-bit red component byte 4-5 16-bit green component byte 6-7 16-bit blue component
Thus, the color table can update arbitrary entries in the palette.
Following the color table are 18 undetermined bytes. After these bytes, there is a series of RLE-encoded lines. For each line in the image:
first 2 bytes indicate size in bytes of compressed line while (remaining bytes in compressed line) code = next byte in encoded frame if (top bit is set (code & 0x80)) output next byte in encoded frame to decoded frame (257-code) times else copy (code + 1) bytes from encoded frame to decoded frame