ANSI SCTE 197 pdf free download

ANSI SCTE 197 pdf free download.Recommendations for Spot Check Loudness Measurements.
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’. The document also recommends some approaches for interpretation of the measurement data and for actions to be taken.
4.0 MEASUR EMENT BASIS Loudness measurements for spot checks should be made using the principles of ATSC RP A/85 and the ITU-R Rec. BS.1 770 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.
6.0 DATA ANALYSIS In general, the operator is able to monitor and log loudness measurements of 24 hours of continuous programming but may not know which portions are commercials and which portions are long form programming. Consequently, the operator should analyze the logged results to determine if there are any periods of content which potentially are non-compliant with A/85 [1], then determine whether those periods occurred during a commercials. The steps are as follows: 1. Compare each recorded measured loudness value for the 24-hour period with the transmitted dialnorm recorded for that measurement. 2. Process the data to determine if a collection of measurements, taken together indicate there was a significant period (i.e., comparable to lengths of the commercials in the source) where the loudness exceeded the loudness metadata value (dialnorm for AC-3). The processing method is expected to vary by entity and to evolve with experience, hence none is recommended. Techniques may include averaging, voting, volatility analysis, sample processing, or others. 3. If a period of measured loudness exceeds the dialnorm value for a significant period by more than the criteria’ defined by the operator, note this as a potential discrepancy by a commercial and note the magnitude, time and duration of the apparent excess loudness. Such discrepancies may be legitimate over short periods for all content and may occur over longer periods for some forms of long form programming, but are an indication of a potential loudness discrepancy of a commercial.ANSI SCTE 197 pdf download.