diff --git a/pyav_by8 b/pyav_by8
new file mode 100644
index 0000000..c1e9987
--- /dev/null
+++ b/pyav_by8
@@ -0,0 +1,13 @@
+try to create an image with a custom buffer, format rbga
+image is 278x57
+got 63384 bytes, need 63840 bytes
+63384=278*57*4, checks out.  why 63840?
+factor 63384=2*2*2*3*19*139
+factor 63840=2*2*2*2*2*3*5*7*19
+factor 278=2*139
+factor 57=3*19
+factor 4=2*2
+63840 doesn't have 139 as a factor... if we divide by the other two we get 2*2*2*5*7=280
+is it padding an extra pixel on each side?  no, reducing video frame width to 276 still demands 63840 bytes.
+does stretching image to 280 work?  yes!  so it has to be a multiple of 5... or 10, or 20.  and larger than the requested dimension.
+after some further fiddling, it's 8.