Note: The Multimedia File System is distributed as an optional eCos
package. This package is not provided as standard within eCosPro
Developer's Kits.
This document describes the Multimedia Filesystem (MMFS) provided in
eCos. This is implemented by the MMFS package which uses the
facilities of the FILEIO package to present its functionality to the
user.
MMFS is intended to support continuous media intensive applications
such as Personal Video Recorders, Video JukeBoxes and
Video-on-Demand. It is designed to support the recording and playback
of data streams at constant and variable rates.
MMFS was designed with the following goals:
Provide PVR functionality allowing several data streams to be recorded
simultaneously while also replaying a stream, which may be one of the
streams being recorded. Provide the ability to fast-forward and rewind
data streams.
Make efficient use of disk storage, access times and bandwidth.
Automatic recovery of disk data structures on restart after a power
failure or other interruption. Automatic formatting of a new disk or
one that is irretrievably corrupt.
These goals are achieved by simplifying the filesystem as much as
possible. So, for example, there is only one directory that contains
all files; file metadata is permanently allocated and of fixed size;
caches are small and special-purpose. Many aspects are configurable so
that the filesystem may be tuned to the application.
