NvIFRSetUpHWEncoder error "invalid parameter" if dwNBuffers > 3

Trying to set number of buffers more than 3 in NvIFRSetUpHWEncoder I get error NVIFR_ERROR_INVALID_PARAM. Reproducible in samples, e.g. DX11IFR_AsyncHWEncode, change to


I haven’t found any info about this limitation in the documentation. I was trying to increase number of buffers to smooth async processing. Is it a bug or a genuine limitation?

AWS g3.4xlarge instance