Fixes: signed integer overflow: -2147483616 - 64 cannot be represented in type 'int'
Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_ADS_fuzzer-6617769344892928
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit c78b2b138ce222de2f4cecac8fd4361f05ee9428)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>