Kostya: Created page with "* FOURCCs: VQC1, VQC2, VQS1, VQS2 * Company: VideoQuest Technologies Inc * Samples: ??? There seem to be four different codec IDs that somewhat differ in frame header for..."

2021-01-01T10:33:51Z

Created page with "* FOURCCs: VQC1, VQC2, VQS1, VQS2 * Company: VideoQuest Technologies Inc * Samples: ??? There seem to be four different codec IDs that somewhat differ in frame header for..."

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* FOURCCs: VQC1, VQC2, VQS1, VQS2
* Company: [[VideoQuest Technologies Inc]]
* Samples: ???

There seem to be four different codec IDs that somewhat differ in frame header format but they all employ the same compression which is splitting frame into stripes, applying 1-D transform which looks like LGT 5/3 wavelet transform, and coding result in 32-bit chunks using fixed quantisation and variable-length codes.

== Data Format ==
After the frame header the actual data follows. Bitstream is coded MSB.

Data is coded as 32-byte chunks with the following scheme: first two bytes are transmitted as is and the rest is coded with the following codes.

10 - end of chunk
00 - output 0
0100 - skip 3 entries
0101 - skip 4 entries
0110 - skip 5 entries
0111 - skip 6 entries
1100 - output 1
1101 - output -1
111000 - output 2
111001 - output 3
111010 - output 4
111011 - signed 8-bit value follows, 0=end of data
111100 - output -2
111101 - output -3
111110 - output -4
111111 - signed 6-bit value follows

After that values are expanded using fixed quantisation tables and three-pass wavelet transform is applied.

Transform:

s0 = y0[0] + (y1[0] >> 1);
for (i = 0; i < size / 2 - 1; i++) {
dst[i*2] = s0;
s0 = y0[i + 1] + ((y1[i] + y1[i + 1]) >> 1);
dst[i*2 + 1] = ((dst[i*2] + s0) >> 1) - 2 * y1[i];
}
dst[width - 2] = s0;
dst[width - 1] = y0[size / 2 - 1] + ((y1[width / 2 - 1] - 2 * y1[size / 2 - 2]) >> 2) - y1[size / 2 - 2];

[[Category:Video Codecs]]
[[Category:Undiscovered Video Codecs]]
[[Category:Wavelet Video Codecs]]

ViewQuest VQC - Revision history

Kostya: Created page with "* FOURCCs: VQC1, VQC2, VQS1, VQS2 * Company: VideoQuest Technologies Inc * Samples: ??? There seem to be four different codec IDs that somewhat differ in frame header for..."