OFR, short for OptimFROG, is proprietary lossless audio data compression codec created by Florin Ghido. OFR aims to optimize the high compression ratios and the price of slower encoding and decoding as well. OptimFROG DualStream which aims to fill gap between perceptual coding and lossless coding is another format of OptimFROG file, both of which could store the metadata by using PEv2 tags.

ASF is Advanced Streaming Format. It is an extensible file format developed primarily for storing synchronized digital video, audio, subtitle streams, or transmitting data on the internet. ASF is also a multimedia container of Windows Media Video or Windows Media Audio.

To convert OFR to asf, please install OptimFrog DirectShow decoder filter.


Download ASF Converter which can convert ofr to asf file. Select an ofr file, change audio encoding bitrate if necessary,  rename the output file to asf extension.

RAM means Real Audio Media which is a kind of audio media format developed by Real Networks. ram adopts Realís unique compression algorithm which may audio  data or point to a section of the online audio streams (need network support).

Please install RealPlayer RealMediaSplitter to convert ram to asf.


M4A is the standard file extension of MPEG4 audio. M4A is mentioned in it's standards that the extension of normal file is *.mp4, which becomes popular since itís firstly been used in iTunes and iPod by Apple to differ MPEG4ís audio from its video. Now almost all software that support mp4 could also support m4a files format.

To convert m4a to asf, please install m4a decoder and m4a splitter. If the m4a is protected or encrypted, the conversion will fail.

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