Recently, i’ve been playing with my speakers and i’ve found out that they are not outputting *true* 5.1 audio, when it is available on the HD channel i’m watching. The main issue i was running into was the fact that it was outputting CMSS surround audio (basically, it gets all of the channels, minus the center one, and then upmixes the left and right channels to create a center channel). This had the unfortunate side effect of making music VERY loud during true 5.1 tv shows, and making dialogue impossible to understand (because the center channel is lost, and thats where voices are). The only way to overcome this, that i have found so far was to use the following settings in ac3filter:
SPDIF - AC3 Encoder Bitrate: 320kbps, Use AC3 Encoder.
SPDIF Mode: SPDIF Wrapped.
SPDIF Passthrough: (untick all 3). This allows you to reroute seperate channels on a 2.0/2.1 channel broadcast, and then upmix it to 5.1 (this is what i do).
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That configuration was for standard definition channels, which allows upmixing and re-encodes audio. I prefer that one because it sounds ‘crisper’ than using the raw mpeg audio.
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This configuration is for true 5.1 programmes:
SPDIF - Disable AC3 Encoder.
SPDIF Mode: SPDIF Wrapped.
SPDIF Passthrough: AC3 Ticked.
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That option will pass the untouched 5.1 channel audio from the tv station directly through to your speakers/decoder. Using these configurations, you can easily switch between upmixed and original audio.
Before i finish, i just have to say that it taken me days on google to figure this problem out, so i hope it helps someone else in the future.
