3G2 is a digital multimedia container format developed by the Third Generation Partnership Project (3GPP). It can save both video and audio tracks, just like its sister format, 3GP. However, it’s the updated version of the former because it is designed for CDMA (Code Division Multiple Access) mobile phones, whereas 3GP is intended for GSM phones.
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MKV is a container format for holding multiple audio, video, picture, and text data such as subtitle tracks. It is similar to other common containers like MP4 and AVI, although MKV is open in the specification. For video contents, MKV uses a .mkv filename extension, .mka for audios, and .mks for subtitles.
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