Convert M4V to OPUS

It is a format for audio files which compresses the audios using lossy compression. It neglects the redundant information which can not be processed by the human ear. Internet Engineering Task Force (IETF) has standardized this format. It has superseded the Vorgis and Speex. It offers low latency i.e. there is a less delay in the signal when it enters the system and when it emerges out, this results in real-time interactive communication like video conferencing. Due to its good audio quality, it is widely used by in various listening tests.

OPUS has good compatibility with low-end embedded processors as it is less complex. Ranging from 6kbps to 510kbps, it can support both variable and constant bitrate coding. Also, the frame size from 2.5ms to 60ms is supported by this codec. It works smoothly and maintains stability (by avoiding the distortion) while mixing of packets from distinct streams. Speech, Hybrid and pure-CELT are the three different methods used for encoding the audios of varied frequencies. For compressing the Speech up to 8kHz, SILk is used which is an audio compression developed by Skype Limited. The next mode, Hybrid uses CELT to compress the audio files above 8kHz frequency or for wider bandwidth and frame sizes 10ms and 20ms are supported by this mode. CELT(Constrained Energy Lapped Transform) is an open and free audio compression format which is especially used in communication that requires low latency. For general audio, the last mode pure-CELT is used. CELT is used for frame sizes which are less than 10ms.