Talk:Dolby Digital Plus

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I removed the reference to Toslink in the Physical Transport section, as Toslink is simply a fibre optic cable format commonly used for S/PDIF, and not a separate interface. smnc (talk) 04:31, 21 January 2009 (UTC)


Should DD+ be used as an abbreviation throughout the article? I am not sure its any sort of offical abbreviation from Dolby.


This isn't the correct term to use. It's called transcoding. —The preceding unsigned comment was added by (talk) 00:17, 5 March 2007 (UTC).

Downmixing refers to reducing the number of channels or reducing the sampling bits. For example from 24 bits per sample to 16 bits.
Transcoding refers to changing the compression algorithm from one format to another or changing the compression parameters. Don't know about the article where this occurs. Daniel.Cardenas 18:37, 10 July 2007 (UTC)
Actually converting from 24 bits to 16 bits would be downsampling, not downmixing. 04:00, 21 October 2007 (UTC)

13.1 channels?[edit]

'13.1 channels' does not make much sense to the layperson (what does the '.1' part refer to?). To improve the article, explain this from the start or link to a section of another page that offers an explanation.--ChrisJMoor 02:44, 17 March 2007 (UTC)

I've attempted to address your concern. Let me know if it doesn't. Unfortunately this is a subject area, where it's easy to slip into Jargonbot mode. Megapixie 09:13, 17 March 2007 (UTC)

Transcoding to AC-3 not required[edit]

As demonstrated by many Toshiba HD DVD players, transcoding to DTS is sufficient. --Ray andrew 16:11, 6 October 2007 (UTC)

Also, transcoding is not necessary at all. IEC 61937-3 describes how to do it for S/PDIFF. SMPTE 340-2008 describes how to do it for AES3. LarsPM (talk) 11:08, 5 August 2011 (UTC)

HDMI EDID Short Audio Descriptor Byte 3[edit]

The HDMI 1.3a Specification, and the corresponding CEA-861D Specification indicate that the EDID value in a Short Audio Descriptor for DD+ support shall be decimal 10 in Byte #2. However there is no specified value for Byte #3. The CEA-861D indicates that the value for Byte #3 is zero, or specified by the Audio Codec Owner. I have searched on the Dolby web page, but cannot find this answer. Can someone help?Calbookaddict 21:19, 12 November 2007 (UTC) In an e-mail from Dolby Laboratories on 13 November 2007, I received the answer: There is no non-zero value defined for Byte 3 of the Short Audio Descriptor for Dolby Digital Plus – it should be set to zero. Byte 1 is used to indicate the Audio Format (set to decimal value 10 for Dolby Digital Plus, indicated in bits 7 to 3) as well as the maximum number of decoded output channels on the sink device (bits 0 to 2). Byte 2 is used to indicate the coded sample rate of the Dolby Digital Plus stream. Calbookaddict 20:55, 15 November 2007 (UTC)


When was dd+ first introduced? Or what other dates are available? Thx, Daniel.Cardenas (talk) 18:54, 15 January 2008 (UTC)

A/52B, which includes E-AC-3, was approved by the ATSC on the 14th June 2005, that would have been the first public introduction of the standard although obviously it was being considered by other standards bodies earlier than that. (talk) 11:53, 20 July 2009 (UTC)


An enormous number of references were to Dolby's old site, which has been redesigned and for which links neither work any more nor have any obvious replacements. I've removed them but the article probably needs a new set of citations to replace the ones deleted. Some of the information posted seems dubious anyway, like the supposed "Dolby mandate" to transcode E-AC-3 into AC-3 over S/PDIF (I've deleted that, I don't believe it's true, there are no citations for it, and there's an HD DVD player in my living room that transcodes to DTS instead.)

Anyone who wants to verify some of the uncited "facts" in this article is more than welcome... (talk) 21:02, 19 August 2009 (UTC)

Any objection to my posting an official link with detail on the technical specifications for Dolby Digital Plus? Disclosure: I am a Dolby Press Officer.

Armstid (talk) 23:15, 17 May 2010 (UTC)

Backward Compatibility[edit]

Entry notes Dolby Digital Plus bitstreams "are not backward compatible with legacy Dolby Digital decoders." Entry for Dolby states Dolby Digital Plus "is backward compatible" with Dolby Digital. Armstid (talk) 23:15, 17 May 2010 (UTC)

Citing the Digital Audio Compression Standard (AC-3, E-AC-3), available from the ATSC website at, pp. 19/20:
Revision B of this standard was approved by the full ATSC membership on 14 June 2005. Revision B corrected some errata in the detailed specifications, and added a new annex, "Enhanced AC-3 Bit Stream Syntax" which specifies a non-backwards compatible syntax that offers additional coding tools and features.
Enhanced AC-3 is ATSC speech for DD+, so I guess that's the definitive answer.Jaho (talk) 23:28, 30 May 2011 (UTC)


Dolby Atmos is an extension to DD+ and probably warrants a mention/link on the page. [1] [2]