  Sign Languages are rich multi-channel languages, requiring articulation of
both manual (hands) and non-manual (face and body) features in a precise,
intricate manner. Sign Language Production (SLP), the automatic translation
from spoken to sign languages, must embody this full sign morphology to be
truly understandable by the Deaf community. Previous work has mainly focused on
manual feature production, with an under-articulated output caused by
regression to the mean.
  In this paper, we propose an Adversarial Multi-Channel approach to SLP. We
frame sign production as a minimax game between a transformer-based Generator
and a conditional Discriminator. Our adversarial discriminator evaluates the
realism of sign production conditioned on the source text, pushing the
generator towards a realistic and articulate output. Additionally, we fully
encapsulate sign articulators with the inclusion of non-manual features,
producing facial features and mouthing patterns.
  We evaluate on the challenging RWTH-PHOENIX-Weather-2014T (PHOENIX14T)
dataset, and report state-of-the art SLP back-translation performance for
manual production. We set new benchmarks for the production of multi-channel
sign to underpin future research into realistic SLP.
