Unrecognized streams are not allocated
Fixes: flicker-1.color1.vp91447030769.08.webm
Found-by: Chris Cunningham <chcunningham@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit a5034b32)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>