since we all seems to have same issues.
Yes, there are many different opinions—depending on whose response you are reading and how they interpret the indicators on their home theater systems.
What are the best setting for now.
For the most part, I believe this to be a matter of personal preference. On my system all three settings (Auto, Dolby Surround, and Stereo) appear to work correctly for their intended purpose (as I understand them). Unfortunately, these settings do affect a user's AVR or HDTV playback indicators which seems to be the major area of controversy. In addition, audio content actually being played back can further confuse the issues. Therefore, for the purpose of my discussion/descriptions, I am limiting my observations to videos with stereo AAC and mono, stereo, DD PL2, or 5.1 AC3 ("legacy" Dolby Digital) encodings and not DTS, DD+, or TrueHD 7.1 content—formats of which I have yet to find valid 8-channel sample files that can be imported into my iTunes media library for testing. Lastly, if you find a setting you like that is working they way you want/expect, don't change it arbitrarily. Settings have habit of sometimes "freezing" in one mode even though the menu indicates you have changed to another mode.
What you all try and result
| TV4 Setting | Track | Mode Indicator | AVR Channel Display | Speaker Output |
|---|
| Auto | AAC | Direct PCM | n/a | L/R |
| Auto | AC3 | Direct PCM | L/C/R/SL/SR/XL/XR/LFE(Active) | As originally encoded |
| Dolby Surround | AAC | DD Digital | L/C/R/SL/SR/LFE(inactive) | L/R |
| Dolby Surround | AC3 | DD Digital | As originally encoded w/Active LFE | As originally encoded |
| Stereo | AAC | Direct PCM | n/a | L/R |
| Stereo | AC3 | Direct PCM | n/a | L/R |
For me, the best "Surround Sound" setting is "Dolby Surround" since it allows my AVR indicators to accurately mirror the actual AC3 encode and speaker output activity. The only major problem I have is an inaccurate AVR display when/if I forget to re-select the AC3 track each time I open a new file. You can reset internal video file flags to automatically select the AC3 track and/or hide a secondary AAC track, but another responder has said this may cause metadata loss. Besides, Apple may correct this issue and I am not anxious to modify thousands of files prematurely if I don't have to do so.
Basically, the "Auto" setting seems to send the source track audio to the AVR or HDTV over a PCM HDMI connection and lets the receiving device deal with it. In this case the stereo AAC data is sent as stereo PCM as with older TV devices but the AC3 data is sent using a 7.1 PCM HDMI connection that incorrectly triggers a display of all PCM surround channels but correctly plays the active audio channels on my system as originally encoded. Others may get different speaker output results here depending on whether or not they have 6-channel fallback capabilities programmed for 8-channel connection and how Apple is actually sending the AC3 data.
On the other hand, the "Stereo" setting seems to unconditionally output everything (mono and stereo AAC or mono, stereo, and surround AC3 audio as PCM stereo.
While I believe there are definitely several issues to be addressed, I can at least live with my current TV4 settings as they are compatible with my older TV2 and TV3 devices, as well as, all of my files as they are now encoded. If you have a problem setting up and/or testing your settings configuration, and you have an iPhone or iPad handy, you may want to download Jeff Perrin's free Speaker Check for Apple TV app utility. I used it to cross check my TV4 and AVR visual activity indicators with what I am actually hearing from the individual speakers since so many people were saying so many different things.
