Files with the .ram file extension are used by RealPlayer to play offline or online audio files on your computer. RAM files contain URLs to other RealMedia files, such as .rm files in which the actual audio or video content is stored.
The first version of RealAudio used a proprietary protocol called PNA or PNM to send streaming audio data. RealNetworks later switched to the IETF standardized Real Time Streaming Protocol (RTSP) but they use RTSP only to manage the connection. The actual audio data is sent with their own proprietary RDT protocol, which they initially kept secret. Recently, some specifications for the RDT protocol have been made public through the Helix Community project. The open-source MPlayer project eventually developed a means of playing the RDT streams.
MP4 files (MPEG-4 Part 14) are multimedia files. MP4 is a container format that can store video, audio and subtitle data (as well as more depending on content). Since stores like iTunes uses this container format, and it is used with iPod and PlayStation Portable (PSP), MP4 files have become more common.
MPEG-4 Part 14 or MP4, formally ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. It is most commonly used to store digital video and digital audio streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. A separate hint track is used to include streaming information in the file. The only official filename extension for MPEG-4 Part 14 files is .mp4.
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