the encoding fails if the width is odd

[David Riccitelli]

One cannot use a scale=-1:240 because the width might be odd. The width must be calculated by the encoder and ensure that it is even.

[David Riccitelli]

see #30: ensure width is even

→ <<cset 25d6258f5452>>

[David Riccitelli]

the fix is part of #24.