Update on Digital Cinema Support for Those with Disabilities: February 2010
by Michael Karagosian
©2009 MKPE Consulting LLC All rights reserved worldwide
Closed caption technology for digital cinema is rapidly moving forward with the successful standardization of SMPTE 430-10 and 430-11 for the SMPTE CSP/RPL closed caption output, the standardized closed caption output for digital cinema servers. The SMPTE CSP/RPL output is not proprietary and is free to implement. Because of this, the National Association of Theatre Owners encourages all digital cinema server manufacturers to include the SMPTE CSP/RPL closed caption output in their products. Wide-spread use of this protocol will allow multiple closed caption systems to emerge.
Summarizing the standards effort for accessibility in digital cinema:
- SMPTE 429-2 describes labeling for the 5.1, 6.1, and 7.1 audio formats in the SMPTE DCP (DCP = Digital Cinema Package)
Note: Each audio format prescribes how to package HI and VI-N accessibility audio, where HI = Hearing Impaired, and VI-N = Visually Impaired Narrative;
- SMPTE 428-10 and 429-12 describe how to prepare and distribute closed caption content in the SMPTE DCP; and,
- SMPTE 430-10 and 430-11 describe the SMPTE CSP/RPL closed caption output from the server.
The SMPTE standards for audio do not prescribe the media block outputs on which HI and VI-N should appear. If not specifically prescribed by exhibitor specifications, these channels may appear on different outputs when switching from 5.1 to another audio format. The chart below prescribes the recommended mapping of SMPTE 429-2 audio tracks to the audio outputs of the media block. Note that HI and VI-N audio are recommended to always be routed to outputs 15 and 16.
Recommended Audio Output Assignment Table For SMPTE 429-2 Audio
ISDCF produced a recommended timeline for the implementation of SMPTE DCP, including all accessibility features named above. Pursuant to the ISDCF timeline, installation of compliant equipment should begin on or by April 2010, and retrofits of legacy equipment should be completed by April 2011. The timeline is [no longer] available online. The document lists all standards required for SMPTE DCP support, including all of the accessibility features described above. It is recommended that the timeline be included in equipment purchase specifications.
On the device side, USL and Doremi have demonstrated wireless, cup-holder-mounted closed caption displays. USL and Intelligent Access are also demonstrating closed caption glasses, which display closed caption text in front of the wearers eyes while watching the movie. USLs system uses a single infrared transmitter for delivery of assistive listening HI/VI-N audio in addition to closed captions to any of its devices. Doremis RF-based wireless system (IEEE 802.15.4) only supports closed captions and does not support HI and VI-N audio. Intelligent Access also utilizes an RF delivery system (WiFi) for closed captions, and does not deliver assistive listening audio. Both USL and Doremi support the Rear Window™ closed caption system. Of the available closed caption systems, only USL and Intelligent Access support the license-free SMPTE CSP/RPL output. (CSP/RPL is standardized as SMPTE 430-10 and 430-11.) Server manufacturers that wish to employ the Doremi closed caption system should contact Doremi for licensing information.
For more information on closed caption systems for digital cinema: