Available streams
VIC Video Stream (ID 0)
The VIC Video Stream is the stream that presents the active part of the video output of the VIC.
The ID of this stream is 0.
Each UDP datagram contains a header and pixel data. The header is as follows:
• Sequence number (16 bit LE)
• Frame number (16 bit LE)
• Line number (16 bit LE). If this is the last packet of the frame, bit 15 will be set.
• Pixels per line (16 bit LE), always 384
• Lines per packet (8 bit), always 4
• Bits per pixel (8 bit), always 4
• Encoding type (16 bit), always 0 for now. May be ‘1’ later for RLE encoded data.
Example packet:
The following packet contains data of the third frame, line 100 - 103, starting with dark blue:
A1 00 02 00 64 00 80 01 04 04 00 00 66 66 66 66 66 66 66 ...
seq #|frm #|line#|width|lp|bp|-enc-|data....................
So in total, the pixel data is preceded with 12 bytes of header data. The header is followed by pixel
data, coded in 4-bit VIC colors, little endian, thus nibble 3..0 first. 4 lines of 384 pixels, equals 768
bytes of pixel data. Total UDP datagram = 780 bytes.
To capture an entire frame, you first wait for a packet with bit 15 set of the line number, then
capture until you get another packet with bit 15 set of the line number. You should then have 68
packets of 4 lines (totaling 272 lines). Note that the video is cropped to 384 x 272, and aligned with
the reference images of the VICE test suite. The actual output to the screen is 400 x 288 in PAL
mode.
In NTSC mode, the output stream carries 384 x 240 pixels. The actual output to the screen is 400 x
240.
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