dav1d: Only drain at most one decoded frame per input frame unless the decoder...

dav1d: Only drain at most one decoded frame per input frame unless the decoder requires more before accepting new data

This works around a race condition in dav1d where the decoder deadlocks if multiple threads are used, and also is generally beneficial as it allows for proper frame threading.

assigned to @gstreamer-merge-bot

added Needs backport label

mentioned in commit slomo/gst-plugins-rs@d1109775

mentioned in commit slomo/gst-plugins-rs@037294b0

added 4 commits

• d1109775 - dav1d: Only drain at most one decoded frame per input frame unless the decoder...
• c5a625ae - dav1d: Don't flush the decoder when draining
• f62d0763 - dav1d: Remove unnecessary frame dropping loop
• 037294b0 - dav1d: Get rid of some unnecessary `unwrap()`s

Compare with previous version

mentioned in commit slomo/gst-plugins-rs@c5a625ae

mentioned in commit slomo/gst-plugins-rs@f62d0763

merged

mentioned in commit slomo/gst-plugins-rs@2cd3774b

mentioned in commit slomo/gst-plugins-rs@daa60a96

mentioned in commit slomo/gst-plugins-rs@19f946e1

mentioned in commit slomo/gst-plugins-rs@71dbf7c6

removed Needs backport label