Test 4 Result: Time Gap Test - Nielsen ID3 User Manual

The PCM-to-ID3 SDK issues a new sequence number for each ID3 tag (INFO or DATA)
that is generated. A missing sequence number indicates that an ID3 tag with that
sequence number was generated, but the tag was not delivered to the ID3 tag stream
being evaluated.
The reason for dropped tags is related to the type of file being evaluated. If a viewer fast-
forwards during playback on a tablet, the log file may indicate ID3 tags were dropped.
If the tags were extracted from an MPEG-2 transport stream or an MPEG-DASH stream,
the multiplexer or packager could have failed to include the ID3 tags in the PES. In
investigating tag-sequence errors, you must consider all possible points along the
distribution chain where tags potentially could be dropped.
In a facility with a fail-over system, the tag sequence numbers of the primary and fail-over system are not
synchronized.
close. A tag overlap or a tag gap of up to 9 seconds may exist at the point of the fail-over.
If there are sequence number errors, but no tag-gap errors, ignore the sequence-number
errors because you can safely assume they result from switching to a fail-over system.

Test 4 Result: Time Gap Test

Format
Format
Number of Errors
0
Maximum Tolerated
Test Result Meaning
Under ideal conditions, each DATA tag begins when the previous tag ends. A notable
exception to this rule occurs when a tag stream includes ID3 tags from two different tag-
generators (a primary device and a fail-over device). If the tag start and stop times
indicate that a time gap or time overlap of more than 9 seconds occurred between tags,
Validator reports a time-gap error. Validator ignores any gap or overlap of 9 seconds or
fewer. See also "Test 13: INFO Tag Interval Test" on page 33.
Example
The example below shows that Validator found three gaps in time between consecutive
tags. The test passed because Validator allows up to six gaps.
Release 1.8 Revision F
-52: Seqno Error and Gap in Tag Times (xx seconds): Sequence
Number xx, Tag time xx.
The tag times and watermark times of the two systems, however, should be
<number of time-gap errors / 0 / maximum
tolerated>
Number of errors detected
Not used
Maximum number of errors tolerated before failure is declared
ID3 Tag: Time Gap Test: Pass <3/0/6>
24
ID3 Tag Validator Application User Manual
Nielsen Confidential