It sounds like the overall dvd bit rate is too high!!! Make sure audio is in dolby surround ac-3 format & that the "maximum" video bit rate does not exceed 8 or so (maximum is not average or target bit rate!!!) Certainly no higher than 8.5. Some dvd players can't handle dvd bit rates that are higher than 9. And dvd bitrates are the total of audio & video bitrates combined including menus. So aim for a "overall" bitrate of less than 8.5 Again, keep in mind maximum video bit rate when doing this.

Either your video joiner or converter at fault by the sounds. Recheck their settings very carefully.