Fixes: 6037/clusterfuzz-testcase-minimized-5030249784934400
Fixes: signed integer overflow: 256 * 16992036 cannot be represented in type 'int'

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>