2012/05/14 (2012/05 Archive)
.knob file format
Can anyone write a Mac Finder extension for JKnobMan's .knob thumbnailing...? Unfortunately, I'm not so familiar with mac development. Anyway the necessary information is here.
There are 2 types of .knob format
Old version : "PNG" type
The first 2bytes are "0x89, 0x50". The file extension is ".knob" but the file contents is the thumbnail PNG image itself (The knob information is embedded in the PNG's text chunk). This format is obsoleted because some browser (IE) forcibly process as Image-file.
Current version : "KM" type
The first 2bytes are "0x4b, 0x4d" (KM).
| Signature | 2bytes | 0x4b, 0x4d //"KM" |
| Offset | 4bytes | Offset to KnobData |
| PNG Image | vairable length | thumbnail PNG image (lacking the first 6bytes) |
| KnobData | variable length | Information for knob |
Because PNG's first 8 bytes are fixed header, knob-file can be easily processed as a thumbnail png image with overwriting the first 6byte to "0x89,0x50,0x4e,0x47,0x0d,0x0a".
Posted by g200kg : 2012/05/14 01:19:22