Test streams

The test stream generator produces a complete SPTS stream with a test pattern and an audio tone entirely in software — no external source is required. It is used as an on-air placeholder while the primary source is down, for verifying transmission paths and receivers, and for setup and load testing.

A test source is an input of type test-stream on an SPTS stream (not available for MPTS). Generation is performed by the software transcoding module — the corresponding package must be installed on the node (Transcoders). Since this is an ordinary input, the general redundancy rules apply: the generator is placed last in the input list, so that it automatically takes over the air when all primary sources fail; the return to a higher-priority input follows the general re-check rules (Source redundancy).

The generated stream passes through the normal processing pipeline (Processing pipeline): it can be analyzed, distributed over transport protocols and to OTT, recorded to DVR, and fed to the multiplexer and to the transcoder.

Generator settings

They are set on the test-stream input (names as shown in the interface; some of them are advanced settings):

Video

Video encoder — the codec: MPEG-2, H.264 (default) or HEVC; Video bitrate (kbps) — the video bitrate (3000 by default); Width and Height — the resolution (1920 × 1080 by default); Frame rate — the frame rate (25 by default); GOP interval — the GOP length in frames; Video pattern — the type of test pattern; Width PAR / Height PAR — the pixel aspect ratio.

Audio

Audio encoder — the codec: MPEG-1 Layer II (default) or AAC; Audio waveform — the shape of the audio signal; Audio frequency (Hz) — the tone frequency; Audio volume — the volume (0…1).

Overlay

Enable overlay — enables the overlay on top of the test pattern (enabled by default); Overlay text — arbitrary text, for example the channel name; Time format (strftime) — the format of the overlaid time, hours:minutes:seconds by default.

Transport stream

Total bitrate (kbps) — the overall stream bitrate, padded with NULL packets (stuffing) to a constant value, 0 — no stuffing; PNR, PMT PID, Video PID, Audio PID — the program number and the identifiers of the PMT table and of the elementary streams, so that the test stream fits the PID plan of the network.

The “Test streams” screen of the web interface (Test streams) is in preparation; test inputs are configured in the stream editor (Input and output editor).