ANSI SCTE 197-2018 pdf free download.Recommendations for Spot Check Loudness Measurements
1.0 INFORMATIVE REFERENCES
The following reference document contains information that may be helpful in applying this Recommended Practice.
1.1 Standards from other Organizations
[1] A/85:2013, Techniques for Establishing and Maintaining Audio Loudness for Digital Television, Advanced Television Systems Committee, 12 March 2013.
[2] SCTE 35 2017, Digital Program Insertion Cueing Message for Cable
2.0 COMPLIANCE NOTATION “SHOULD”
This word or the adjective “RECOMMENDED” means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighted before choosing a different course. “SHOULD NOT” This phrase means that there may exist valid reasons in particular circumstances when the listed behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label. “MAY” This word or the adjective “OPTIONAL” means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.
3.0 INTRODUCTION
As part of managing the relative audio loudness of content, this document provides recommendations for measuring content carried in a single programming channel of a program network for 24-hours with an audio loudness meter consistent with the measurement techniques discussed in A/85 [1] as well as recording the measured loudness and loudness metadata value 1 . The document also recommends some approaches for interpretation of the measurement data and for actions to be taken.
4.0 MEASUREMENT BASIS
Loudness measurements for spot checks should be made using the principles of ATSC RP A/85
and the ITU-R Rec. BS.1770 algorithm, as further specified below.The spot check should be conducted after the signal has passed through the operator’s processing equipment. The monitoring point should therefore be after any equipment in the distribution path that is designed to alter the loudness of the audio stream. For this procedure,access is required to the audio content as encoded for distribution to the consumer and also to any accompanying loudness metadata (dialnorm if AC-3).
Input to the loudness measurement device should be either:
1. A compressed audio (AC-3 or other codec) bitstream as encoded for distribution to the consumer;
2. A transport stream for the cable service, which includes the compressed audio (AC-3 or other codec) bitstream; or,
3. Taken from the un-decoded compressed audio (AC-3 or other codec) output of a cable set-top box.
5.0 TEST PROCEDURE
1. Follow the manufacturers’ recommendations prior to the commencement of testing.
2. Record the make, model number and software version of each unit of test equipment used for the test.
3. Record identifying information on the content source and the date and time measurements commence.a. If content is recorded for later measurement, log the date and time recordings commence. At time of later measurement, log the offset between recording time and measurement time.
4. Set the loudness measurement integration time to 1 second, 400 ms or 100 ms if available equipment supports any of these modes. If not then set to the most preferred sliding window average integration time available according to Table 1 2 .
5. Log the measured loudness, the loudness metadata value ( dialnorm if AC-3), and the date and time of day of each logging period according to Table 1.
6. Continue the log for 24 continuous hours. If content is not available for 24 continuous hours,continue logging measurements as content is available until 24 hours of content measurements are recorded. The minimum number of valid entries should equal 86,400.
