Surround sound for MKV AAC

[alor95]

Hi,

I am trying to watch some 720p MKV files with AAC audio, but when I open the file the audio comes out as stereo only, and not on my surround sound system. I am using K Lite Mega pack codecs (with ffdshow). I am using Win7 64 bit.



Edit: Also, I am using WMP 12. Opening the file in Windows Media centre or VLC works fine with surround, but I prefer WMP interface, etc. Any help appreciated. Thanks.

[Selur]

configuring ffdshow to reencode the audio to ac3 on-the-fly should help assuming ffdshow is used as decoder,.. (no clue about codec packs, I don't use them since from my point of view they do more harm than good)

[jman98]

I suggest verifying that you really have surround AAC audio. You can do this by either installing MediaInfo and seeing what it tells you about the files or you can install MKVtoolnix and put the files one at a time in MKVExtractGUI2 and see if they report surround AAC. Surround AAC is possible but I don't know what players support it.

[alor95]

I suggest verifying that you really have surround AAC audio. You can do this by either installing MediaInfo and seeing what it tells you about the files or you can install MKVtoolnix and put the files one at a time in MKVExtractGUI2 and see if they report surround AAC. Surround AAC is possible but I don't know what players support it.

I've noticed some files in the series work with surround sound, some do not.

The audio MediaInfo is the same for both files.

Here is one of the Media Info for a file:
General
Unique ID : 246158924703235075106806565898384821445 (0xB9307C02B6C89B0790C51733B073CCC5)
Format : Matroska
Format version : Version 2
File size : 691 MiB
Duration : 23mn 38s
Overall bit rate : 4 087 Kbps
Encoded date : UTC 2012-04-22 12:13:23
Writing application : mkvmerge v5.5.0 ('Healer') built on Apr 6 2012 21:43:24
Writing library : libebml v1.2.3 + libmatroska v1.3.0

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings, CABAC : No
Format settings, ReFrames : 2 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 23mn 38s
Width : 1 280 pixels
Height : 718 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Language : English
Default : Yes
Forced : No
Color primaries : BT.709-5, BT.1361, IEC 61966-2-4, SMPTE RP177
Transfer characteristics : BT.709-5, BT.1361
Matrix coefficients : BT.709-5, BT.1361, IEC 61966-2-4 709, SMPTE RP177

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : A_AAC
Duration : 23mn 38s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Language : English
Default : Yes
Forced : No

[alor95]

configuring ffdshow to reencode the audio to ac3 on-the-fly should help assuming ffdshow is used as decoder,.

How would I do this?

[Selur]

enable ffdshow audio deccoder configuration->Output->Output format for uncompressed of decoded stream->AC3 (S/DIPF encode mode) this way everything that is decoded by ffdshow and not marked for pass-through will be reencoded on-the-fly to ac3.

[jman98]

The audio MediaInfo is the same for both files.

Here is one of the Media Info for a file:

[ ... ]

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : A_AAC
Duration : 23mn 38s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Language : English
Default : Yes
Forced : No

Look at the part I highlighted in red. This is why you cannot get surround sound. You only have 2 channels in the source.

[Cornucopia]

If that was supposed to be matrixed Dolby Surround/PL/PLII, it still would exist as a 2ch, regardless. Including regardless of if you converted it to another codec (although ANY conversion would include loss, and the loss in the matrix portion is DOUBLY problematic). (or is that "dubbly")

If it wasn't supposed to be DS/PL/PLII, ignore this and listen to what jman98 said (was only 2ch).

Scott

[alor95]

enable ffdshow audio deccoder configuration->Output->Output format for uncompressed of decoded stream->AC3 (S/DIPF encode mode) this way everything that is decoded by ffdshow and not marked for pass-through will be reencoded on-the-fly to ac3.

When I do this, I only get a buzzing sound and no other audio

The audio MediaInfo is the same for both files.

Here is one of the Media Info for a file:

[ ... ]

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : A_AAC
Duration : 23mn 38s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Language : English
Default : Yes
Forced : No

Look at the part I highlighted in red. This is why you cannot get surround sound. You only have 2 channels in the source.

Why does surround sound work for some episodes that have "2 channels" listed in the MediaInfo, yet does not for others?

[Cornucopia]

Read post #8 (again?).

Scott

[alor95]

If that was supposed to be matrixed Dolby Surround/PL/PLII, it still would exist as a 2ch, regardless. Including regardless of if you converted it to another codec (although ANY conversion would include loss, and the loss in the matrix portion is DOUBLY problematic). (or is that "dubbly")

Scott

Sorry, I don't understand this What would I have to do to resolve it?

[Cornucopia]

Search this site for "Dolby surround upmix". You should find some tools and guides that should help.

Iow, some 4ch may be posing as 2ch, while others truly ARE just 2ch. "Sometimes, a banana is just a banana, Anna."

Scott