The default wavelet used by the snow codec in ffmpeg is a symmetric biorthogonal compact 9/7 wavelet with rational coefficients with properties very similar to the famous biorthoginal daubechies 9/7 wavelet, it was found by bruteforce search with the goal of having a simple lifting implemenattion and having many vanishing moments or almost vanishing moments, the daubechies wavelet has (4,4) our wavelet has (4,2) vanishing moments
The lifting coefficients are:
dau97 
snow 
0.443506852 
15/32 
0.882911075 
4/5 
0.052980118 
1/16 
1.586134342 
3/2 
The resulting wavelet and scaling functions look like:
One thing which is still annoying is the 4/5, while this can be approximated pretty well by a multiplication and a shift right but this tends to overflow so something like
x += x+x;
x += x>>4;
x += x>>8;
x >>= 2;
is needed, this one only differs from 4/5 by a factor of ~0.00001, alternatively the 4/5 can be merged into the unquantization step so that
\  /\  /\  /\  /\
\/  \/  \/  \/ 
+  +  +  +  15/32
/\  /\  /\  /\ 
/  \/  \/  \/  \/
 +  +  +  + 4/5
\  /\  /\  /\  /\
\/  \/  \/  \/ 
+  +  +  +  +1/16
/\  /\  /\  /\ 
/  \/  \/  \/  \/
 +  +  +  + +3/2
is changed to
\  /\  /\  /\  /\
\/  \/  \/  \/ 
+  +  +  +  3/8
/\  /\  /\  /\ 
/  \/  \/  \/  \/
( + ( + ( + ( + 1
\ + /\ + /\ + /\ + /\ +1/4
\/  \/  \/  \/ 
+  +  +  +  +1/16
/\  /\  /\  /\ 
/  \/  \/  \/  \/
 +  +  +  + +3/2
Now lets compare quality between the snow and daubechies 9/7 wavelets, this comparission has been done with JasPer with this change and tinypsnr (from ffmpeg) The used test image was the 256×256 lena grayscale image
Daubechies 9/7 wavelet 
Snows 9/7 wavelet 
size 
PSNR 
618 
24.02 
1283 
27.32 
3194 
31.80 
6503 
36.82 
13079 
42.93 
22945 
47.14 

size 
PSNR 
622 
24.03 
1295 
27.33 
3212 
31.82 
6519 
36.83 
12981 
42.87 
22941 
47.18 
