how to add customized opus codec to webrtc

I want to add customized opus codec to webrtc, and use another variable rtc_opus_custome_dir to point to the customized opus codec. When using gn gen, there are some error messages, e.g.

ERROR at //build/config/BUILDCONFIG.gn:569:5: Duplicate output file.
target(_target_type, _target_name) {
^———————————–
Two or more targets generate the same output:
opus_compare

This is can often be fixed by changing one of the target names, or by
setting an output_name on one of them.

Collisions:
//third_party/opus-v1.4:opus_compare
//third_party/opus:opus_compare

See //build/config/BUILDCONFIG.gn:569:5: Collision.
target(_target_type, _target_name) {
^———————————–
ninja: Entering directory `out/rel’
ninja: error: loading ‘build.ninja’: No such file or directory