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cb97ccdfeb
This splits the schema and playback path. The recording path still adjusts the frame durations and always says the wall and media durations are the same. I expect to change that in a following commit. I wouldn't be surprised if that shakes out some bugs in this portion.
67 lines
3.6 KiB
Markdown
67 lines
3.6 KiB
Markdown
# Moonfire NVR Glossary
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*media duration:* the total duration of the actual samples in a recording. These
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durations are based on the camera's clock. Camera clocks can be quite
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inaccurate, so this may not match the *wall duration*. See [time.md](time.md)
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for details.
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*open id:* a sequence number representing a time the database was opened in
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write mode. One reason for using open ids is to disambiguate unflushed
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recordings. Recordings' ids are assigned immediately, without any kind of
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database transaction or reservation. Thus if a recording is never flushed
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successfully, a following *open* may assign the same id to a new recording.
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The open id disambiguates this and should be used whenever referring to a
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recording that may be unflushed.
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*recording:* the video from a (typically 1-minute) portion of an RTSP session.
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RTSP sessions are divided into recordings as a detail of the
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storage schema. See [schema.md](schema.md) for details. This concept is exposed
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to the frontend code through the API; see [api.md](api.md). It's not exposed in
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the user interface; videos are reconstructed from segments automatically.
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*run:* all the recordings from a single RTSP session. These are all from the
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same *stream* and could be reassembled into a single video with no gaps. If the
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camera is lost and re-established, one run ends and another starts.
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*sample:* data associated with a single timestamp within a recording, e.g. a video
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frame or a set of
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*sample file:* a file on disk that holds all the samples from a single recording.
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*sample file directory:* a directory in the local filesystem that holds all
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sample files for one or more streams. Typically there is one directory per disk.
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*segment:* part or all of a recording. An API request might ask for a video of
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recordings 1–4 starting 80 seconds in. If each recording is exactly 60 seconds,
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this would correspond to three segments: recording 2 from 20 seconds in to
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the end, all of recording 3, and all of recording 4. See [api.md](api.md).
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*session:* a set of authenticated Moonfire NVR requests defined by the use of a
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given credential (`s` cookie). Each user may have many credentials and thus
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many sessions. Note that in Moonfire NVR's the term "session" by itself has
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nothing to do with RTSP sessions; those more closely match a *run*.
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*signal:* a timeseries with an enum value. Signals might represent a camera's
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motion detection or day/night status. They could also represent an external
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input such as a burglar alarm system's zone status. See [api.md](api.md).
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Note signals are still under development and not yet exposed in Moonfire NVR's
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UI. See [#28](https://github.com/scottlamb/moonfire-nvr/issues/28) for more
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information.
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*stream:* the "main" or "sub" stream from a given camera. Moonfire NVR expects
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cameras support configuring and simultaneously viewing two streams encoded from
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the same underlying video and audio source. The difference between the two is
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that the "main" stream's video is typically higher quality in terms of frame
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rate, resolution, and bitrate. Likewise it may have higher quality audio.
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A stream corresponds to an ONVIF "media profile". Each stream has a distinct
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RTSP URL that yields a difference RTSP "presentation".
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*track:* one of the video, audio, or subtitles associated with a single
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*stream*. This is consistent with the definition in ISO/IEC 14496-12 section
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3.1.19. Note that RTSP RFC 2326 uses the word "stream" in the same way
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Moonfire NVR uses the word "track".
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*wall duration:* the total duration of a recording for the purpose of matching
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with the NVR's wall clock time. This may not match the same recording's media
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duration. See [time.md](time.md) for details.
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