If there are several volumes in the object archive (see General information about server archives), the archive recordings are distributed among all volumes by the Round-robin algorithm.

The archive recordings are distributed in a round-robin cycle:

  1. Key frames of a recording are divided into intervals.

    Note

    • Key frames are reference frames of the video that contain complete information about a scene.
    • The algorithm distributes key frames to the archive volumes. Intermediate frames are linked to the corresponding key frames and recorded to the same volume.
    • When writing, the algorithm processes the first key frame along with its intermediate frames. When the second key frame is reached, it is also written along with its intermediate frames to the next volume.
  2. The first interval is recorded to the first volume of an archive.
  3. The next interval is recorded to the second volume of an archive, and so on until the last volume is reached.
  4. When the last volume is reached, the process is repeated until all key frames are completely distributed over available volumes.

This algorithm allows increasing the writing speed of an archive, as well as preventing the loss of recordings for a certain period, in case there are problems with archive volumes, that is, if an archive volume is lost, the recordings for the previous period are available with frame decimation. This behavior is ensured because key frames of recordings are distributed evenly over all available volumes of an archive.

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