[mythtv-commits] Ticket #6569: ac3 level is low for 5.1 source

[MythTV]

#6569: ac3 level is low for 5.1 source
-------------------------------------+--------------------------------------
 Reporter:  markspieth               |       Owner:  janneg  
     Type:  patch                    |      Status:  assigned
 Priority:  minor                    |   Milestone:  unknown 
Component:  MythTV - Video Playback  |     Version:  unknown 
 Severity:  medium                   |     Mlocked:  0       
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Comment(by markspieth):

 this is an issue with '''dolby technical bulletin 11'''.

 what I have done is essentially correct but off by 1 dB. they recommend 11
 dB attenuation an all non ACE/EAC3

 from a bit of web searching
 {{{
 For receivers
 featuring E-AC3, this should be consistent with Dolby Technical Bulletin
 11: Requirement Updates for AC3
 and E-AC3 in DVB Products [34]. Receivers featuring AC3 or E-AC3 decoding
 shall include the PCM Level
 Control feature described therein. For example, for MPEG-1 Layer 2 audio
 streams that have an average
 loudness of about -20 dBLeq, the receiver shall apply an attenuation of 11
 dB for the digital output to
 match the internal reference level.
 }}}

 Cant find a copy of this bulletin but the concept is there. Something to
 do with RFMode.

 Another spec Ive seen says reduce by a further 3dB on top of the 11dB.

 Thus this should be consistent around the world and not just peculiar to
 some implementations.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/6569#comment:7>
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