MP4 muxer video input format

Dear Intel Support,

I've tried the MP4 muxer (umc_mp4_mux) from the examples using H264, and it worked well when the video source came from Intel H264 encoder. On the other hand I would like to use this muxer with an existing source H264 of annex B stream. The problem which I figured out so far is that if this H264 stream has multiple slices per frame from an external stream, the video has gibberish content, and the player complains about various errors, including "Invalid mix of IDR and non-IDR frames". When there is only one slice per frame, the output video is OK. I've tried to use PutVideoData() on frames containing the concatenated slices in annex B format, but it didn't get any better.

I would like to use this stream without reencoding. I'm using Intel IPP samples 7.1.1.013.

Thanks for your help!