3fa747fb

By: Michael Lynch <git@mtlynch.io>

Preserve GIF timing in Tinybeans AVIF imports

The previous ffmpeg invocation hard-coded libaom-av1 and let ffmpeg
resample GIF frame delays. On current ffmpeg builds that either failed or
flattened the original GIF timing into a synthetic constant rate.

Select the available AV1 encoder up front, centralize the ffmpeg argument
construction, and pass through the GIF centisecond time base so imported
animated AVIFs play at the intended speed.

Timeline