ตัวแปลงไฟล์ออนไลน์ฟรี SPX เป็น M4R

An SPX file is a Speex audio file saved within an Ogg Vorbis container. Speex is an open source patent-free audio format designed for speech compression. It supports variable bitrate (VBR) encoding and several features not found in other audio codecs. Some examples include embedded encoding, intensity stereo encoding, and voice activity detection.

M4R - is a digital multimedia container format used to store audio in mono channel mode. This format is suitable for store ringtones and it is widely used by Apple iPhone for its ringtones. Needless to say that M4R and M4A formats shares many similar features.