ISO 26432-2:2008 PDF

Digital source processing — Part 2: Digital cinema (D-cinema) low frequency effects (LFE) channel audio characteristics

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Title (English):

ISO 26432-2:2008

Digital source processing — Part 2: Digital cinema (D-cinema) low frequency effects (LFE) channel audio characteristics

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 2
Publication date:: July 9, 2008
Edition:: ISO IS 26432 edition 1 version 1
ICS:: 37.060.99

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Description (English):

ISO 26432-2:2008 addresses the interoperability of equipment from the standpoint of the frequency response of filters used in the playback or monitor path in the theatre low frequency effects (LFE) channel for digital cinema. This response curve will create standardization of these filters without specifying their design.

Technical details

Technical committee: ISO/TC 36 - Cinematography
SKU: ISO 26432-2:2008

Abstract

Overview

ISO 26432-2:2008 - "Digital source processing - Part 2: Digital cinema (D‑cinema) low frequency effects (LFE) channel audio characteristics" defines standardized electrical frequency‑response characteristics for the LFE playback or monitor path in D‑cinema environments. The standard specifies a response curve (turnover frequency, slope and allowable deviations) to ensure interoperability of cinema playback equipment without mandating specific filter designs.

Key topics and requirements

Turnover frequency
- Defined as the point where the filter response is –3 dB from the passband reference.
- Required turnover frequency: 125 Hz (± 5 Hz).
Filter slope / Reference response
- The LFE filter slope follows the Reference Filter Frequency Response Table (see values below). The standard prescribes the response curve rather than a circuit topology or implementation.
Passband deviation
- Allowed deviation within the passband: ± 1 dB.
Reference Filter Frequency Response Table (specified points)
- 25 Hz: 0 dB
- 31.5 Hz: 0 dB
- 40 Hz: 0 dB
- 50 Hz: 0 dB
- 63 Hz: 0 dB
- 80 Hz: 0 dB
- 100 Hz: 0 dB
- 125 Hz: −3 dB
- 160 Hz: −45 dB
- 200 Hz: −102 dB

Applications and practical value

ISO 26432-2 is practical for anyone responsible for producing, delivering or reproducing low‑frequency audio in theatrical digital cinema:

Cinema equipment manufacturers - to design LFE playback filters that are interoperable with industry playback chains.
Theatre audio system integrators and calibrators - to verify and tune monitor or playback LFE response to the standardized curve.
Post‑production and sound designers - to understand playback expectations for LFE content and ensure mixes translate correctly in D‑cinema playback.
Quality assurance and compliance testing - for verifying that playback/monitor chains meet specified passband flatness and turnover tolerances.
Standards bodies and facility spec writers - for inclusion in procurement or certification criteria for D‑cinema systems.

Adopting this standard reduces variability in the low‑frequency channel across venues, improving consistency of audience experience and simplifying system integration and certification.

Related standards

SMPTE EG 432‑2‑2006 (original engineering guideline adopted into ISO 26432‑2)
SMPTE 202M‑1998 - Motion‑Pictures: Dubbing Theaters, Review Rooms and Indoor Theaters - B‑Chain Electroacoustic Response
SMPTE RP 200‑2002 - Relative and Absolute Sound Pressure Levels for Motion‑Picture Multichannel Sound Systems

Keywords: ISO 26432-2, D‑cinema, digital cinema, LFE, low frequency effects, turnover frequency, filter slope, reference filter response, audio interoperability.

Related standards

Other ISO standards

Abstract

Overview

Key topics and requirements

Turnover frequency
- Defined as the point where the filter response is –3 dB from the passband reference.
- Required turnover frequency: 125 Hz (± 5 Hz).
Filter slope / Reference response
- The LFE filter slope follows the Reference Filter Frequency Response Table (see values below). The standard prescribes the response curve rather than a circuit topology or implementation.
Passband deviation
- Allowed deviation within the passband: ± 1 dB.
Reference Filter Frequency Response Table (specified points)
- 25 Hz: 0 dB
- 31.5 Hz: 0 dB
- 40 Hz: 0 dB
- 50 Hz: 0 dB
- 63 Hz: 0 dB
- 80 Hz: 0 dB
- 100 Hz: 0 dB
- 125 Hz: −3 dB
- 160 Hz: −45 dB
- 200 Hz: −102 dB

Applications and practical value

ISO 26432-2 is practical for anyone responsible for producing, delivering or reproducing low‑frequency audio in theatrical digital cinema:

Cinema equipment manufacturers - to design LFE playback filters that are interoperable with industry playback chains.
Theatre audio system integrators and calibrators - to verify and tune monitor or playback LFE response to the standardized curve.
Post‑production and sound designers - to understand playback expectations for LFE content and ensure mixes translate correctly in D‑cinema playback.
Quality assurance and compliance testing - for verifying that playback/monitor chains meet specified passband flatness and turnover tolerances.
Standards bodies and facility spec writers - for inclusion in procurement or certification criteria for D‑cinema systems.

Adopting this standard reduces variability in the low‑frequency channel across venues, improving consistency of audience experience and simplifying system integration and certification.

Related standards

SMPTE EG 432‑2‑2006 (original engineering guideline adopted into ISO 26432‑2)
SMPTE 202M‑1998 - Motion‑Pictures: Dubbing Theaters, Review Rooms and Indoor Theaters - B‑Chain Electroacoustic Response
SMPTE RP 200‑2002 - Relative and Absolute Sound Pressure Levels for Motion‑Picture Multichannel Sound Systems

Keywords: ISO 26432-2, D‑cinema, digital cinema, LFE, low frequency effects, turnover frequency, filter slope, reference filter response, audio interoperability.

ISO 26432-2:2008 PDF

Technical details

Abstract

Overview

Key topics and requirements

Applications and practical value

Related standards

Related standards

Abstract

Overview

Key topics and requirements

Applications and practical value

Related standards

Related standards

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