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Overview


Included with the Red5 Pro Server release is a webapp named inspector. You can access the Red5 Pro Inspector from your Red5 Pro Server installation at /inspector.


ABOUT

The inspector evaluates the latency of a publisher.

The server measures how early or late the media packets are. Ideally Video Time and Audio Time would be flat lines at zero, with a drift of zero.

It also graphs the packet size. Placing the packet size and the clock latency on the same display reduces usefulness.

Clicking the color legends at the top will toggle their display in the graph.

VIDEO TIME AND AUDIO TIME

  • Value = (Session Age) - (Packet Timestamp)
  • Positive numbers indicate latency.
  • Negative numbers indicate early arrival.

PACKET BYTE SIZE

  • Value = Total Byte Count of a Media Packet

    • Not including UDP/TCP chunking and formatting for subscribers.
    • This is strictly an AMF media packet size.
    • All subscriber types and FLV recordings will have additional container bytes added for transmission.
  • Positive numbers indicate latency.
  • Negative numbers indicate early arrival.
  • Move the slider to scale down the byte size graph by division. Sliding full to the left graphs raw sizes.

OVERALL AUDIO DRIFT

  • The latency of the first Audio Time is stored until Clear Data is pressed.
  • This value is used to determine how far current Audio Time measurements have changed after several minutes or hours.
  • All other data points are released as the inspector polls the server.

A - V

  • Value = (Last Audio Timestamp) - (Last Video Timestamp)

RAW DATA

The inspector gets a list of JSON objects from the server at regular intervals. The graph is made up of just a few useful models.

The complete list of JSON values per packet is:

  • time: Java UTC this packet was seen at the server.
  • type: Audio or Video
  • amv: Audio minus Video
  • lastAudio: Last Audio timestamp processed.
  • timestamp: Current timestamp from publish start (in milliseconds) set by client.
  • age: Publish session age in milliseconds.
  • delta: Latency measurement.
  • size: AMF packet size; structure defined by Adobe video file format.

The polling cache at the server only holds 149 packets. Video frame rates from 10 to 60 may see a shorter but more dense graph as they get higher.


USAGE

  1. Edit the Path/Name value to the stream you want to inspect.
  2. This must include the app name and stream name separated with a slash.
  3. Click Clear Data.

NOTES

  • Click Clear Data if the stream is republished, or any time you want a reset.
  • The Graph may have gaps if the browser page loses focus due to reduced polling.
  • If you wish to remove the webapp, you must also delete the {red5pro}/plugins/inspector.jar file