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[tzr916]

For Tv shows, I use HDMI and bitstreaming because when I play live or recorded Tv shows (TS files) with AC3 5.1 audio, it shows up on my AVR as "dolby digital" and automatically adds rear surround speakers (7.1). But when I watch mv4, mp4, mkv videos with AAC 5.1 audio, it shows up on my AVR as PCM and I have to manually activate those rear surround in the AVR...
1. Why is AAC being detected on my AVR as PCM?
2. Can I not bitstream AAC to the AVR? How?

Example mv4:

Code: [Select]

Audio
ID                                       : 2
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 49 min 28 s
Bit rate mode                            : Variable
Bit rate                                 : 192 kb/s
Channel(s)                               : 6 channels
Channel layout                           : C L R Ls Rs LFE
Sampling rate                            : 48.0 kHz
Frame rate                               : 23.438 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 68.0 MiB (17%)
Title                                    : Surround / Surround
Language                                 : English
Default                                  : Yes
Alternate group                          : 1
Menus                                    : 4


[wer]

Your question stems from a misunderstanding about audio formats and what bitstreaming is for.

Bitstreaming is used to transmit encoded audio formats, like Dolby Digital, DTS, and Atmos. These formats (esp DD and DTS) exist so that multi-channel data can be encoded and transmitted over a 2-channel audio transport, like S/PDIF. They then require a decoder (your receiver) to convert them back into 5-channel audio.  Atmos is encoded to force the use of Dolby-licensed hardware decoders.

That's not what AAC is.  AAC is a compression mechanism for regular PCM audio, like MP3. It is lossy, like MP3. But when decompressed contains the same type of unencoded audio as MP3, FLAC, WAV, etc.

JRiver, and every other application, decompresses AAC into PCM audio, and transmits it to your receiver as uncompressed PCM audio (unless you've told it to do something different, like encode to AC3).

You can't "bitstream" PCM, because it is not an encoded bitstream. Since you can't bitstream PCM, you can't bitstream AAC, FLAC, MP3, or WAV either.  Asking to bitstream AAC is like asking to bitstream FLAC.

So the short answers to your questions:
1. Because MC decompresses the AAC to PCM to output it
2. No

If your Denon is actually seeing multi-channel PCM, then it should use the appropriate speakers.  So the real question is: Is your Denon not doing what it should, or are you not actually outputting 5.1 PCM?

Check the output format module of DSP Studio in MC to ensure you are not downmixing. Downmixing cannot be applied to bitstreams, since they remain encoded, so if you have it turned on, it would not affect your AC3 streams.

Also check the on-screen display on your Denon, to verify that it thinks it is receiving 5.1 channels of audio. This can be compared with MC's Audio Path display.  Look at page 223 of your Denon Manual.  or:
http://manuals.denon.com/AVRX2200W/EU/EN/GFNFSYcsmwwkkn.php#OKNRMLprsxkdfg

You might need to change your Auto-Surround mode for PCM.  Look at page 124 of your manual.

It might help me to understand what your problem is if you describe specifically how you "manually activate those rear surround in the AVR".

I hope this helps...

[Hendrik]

That's not what AAC is.  AAC is a compression mechanism for regular PCM audio, like MP3. It is lossy, like MP3.

Just for clarification sake, that same description also applies to AC3 (Dolby Digital), or DTS. They are all pretty similar audio codecs conceptually.

But for the original question, well, you cannot Bitstream AAC because its just not part of the HDMI specification to do so. Only audio codecs included in that specification can be bitstreamed, otherwise the receiving end would not understand what is being send.

I had no issues sending only PCM to my AVRs and them do their processing on it. One thing to check would be that you actually send the appropriate number of channels, so that your Denon doesn't think its already receiving 7.1. Or as an alternative, just let Media Center convert it to 7.1.

[wer]

This isn't specific to PCs or software either.  Cable and satellite set-top-boxes will generally have two options for the audio output:  Output as PCM, or re-encode as Dolby Digital AC3.

[tzr916]

DSP is not making changes = 6 channel in, 6 channel out. The AVR is showing PCM (Multi Channel In), but initially it's only playing 5.1 of my 7.1 speakers. I have to go to "Sound Mode", switch it from "movie" to "music", then back to "movie" and then it changes to Multi Channel In + Surround (which adds the two rear speakers to make it 7.1). Thankfully the AVR does remember this for all subsequent playback and switches automatically, until it is powered Off.

None of those steps are needed when playing videos with 5.1 AC3, the AVR automatically adds the "Surround" rear speakers. Was just trying to avoid going to the AVR settings. Oh well, maybe it's a Denon bug or something.

[wer]

Sounds like you are describing the working (or lack thereof) of Denon's Auto Surround mode.  So...

You might need to change your Auto-Surround mode for PCM.  Look at page 124 of your manual.

Try it.

If it doesn't stick when the receiver is powered off, that's a Denon problem.