Fixes: Timeout (14sec -> 29ms)
Fixes: 14733/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CPIA_fuzzer-5707022445576192

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegReviewed-by: Carl Eugen Hoyos <ceffmpeg@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>