זיו,
עשיתי חיפוש ומצאתי משהו שמסכם, לדעתי, את הנושא של השרשור. זה לא מDolby, אך resident expert מאתר hometheaterforum גם לא רע
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There are only two tracks present: one TrueHD and a complementary Dolby Digital track for backward-compatibility. If the TrueHD track can't be processed by a player, the second track is used instead and the TrueHD bypassed entirely.
There is no 'core' legacy Dolby Digital track that can be extracted from 'within' a TrueHD stream. The technologies used by these two formats are fundamentally different and incompatible.
TrueHD doesn't use legacy lossy audio as a foundation (i.e. core plus extension) the way DTS-HD and Dolby Digital Plus do/can. There is simply nothing to extract. If a TrueHD track can't be processed by a player, it is ignored. The separate legacy track(s) that can be processed is/are used instead (PCM, DTS or, in most cases, Dolby Digital). The TrueHD track plays no part at all.
The lack of a legacy core to extract, together with the point made by Michael earlier that TrueHD compatibility isn't mandated in the Blu-ray spec while Dolby Digital is (among others), is why Warner (and others) include a completely separate Dolby Digital track on their discs. How or whether this track is accessed is up to the studio. Warner allows the track to be selected directly via the menu system. Sony instead hides the track and uses logic within the player to play it when required. Both methods still use same two separate soundtracks, however.
If Warner (or Sony etc.) really wanted to, they could include a TrueHD and a DTS-HD track together; or a TrueHD and a PCM soundtrack, or any combination that included a TrueHD soundtrack and a second soundtrack that could be processed by all Blu-ray players (Dolby Digital, DTS or PCM: the formats players are mandated to support) for compliance. They choose to use Dolby Digital because it offers the greatest compatibility for users with legacy equipment.
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http://www.hometheaterforum.com/forum/t ... st_3514872
. למעשה, לא חושב שמישהו עושה את זה, כולל אגב BD PLAYERS שזיו כול הזמן מדבר עליהם (יש בBD פסקול DD נפרד, שהוא בכל מיקרה עדיין mandatory לכל BD, כדי לפתור בעיה של תמיכה אחורה)
לרגע חשבתי....אבל...נו טוב, לא רצה שימחקו שוב את ההודעה שלי.... 
מקווה שזה לא ברצינות. תקרא שרשור מהתחלה.