5.1 AAC - sound too low [Archive]

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AlexeyS

31st July 2005, 22:12

When I try to watch my DVD rips with 5.1 sound on my notebook connected to amplifier (which connected to 5.1 sound system) with SPDIF, I get too low sound. The sound level of notebook was set to highest and sound level of amplifier was set to highest too.

Amplifier and sound system are powerful. For example, if I connect satellite reciever to amplifier with SPDIF cable and turn on amplifier's sound level on maximum - it becomes very loud (impossible to listen).

What is the problem (I'm sure amplifier is not a problem)?

SeeMoreDigital

31st July 2005, 22:42

For a start... when you pass 6Ch AAC over S/P-DIF, it will not be correctly decoded to six separate (discrete) channels by your amplifier. Not unless you're transcoding it to 6Ch AC3... on-the-fly!

Cheers

AlexeyS

1st August 2005, 00:02

AlexeyS

1st August 2005, 00:48

Just tried to switch different modes (Hall, Jazz, 2Ch, AFK, DPL Mov etc). Sometimes amplifier shows all 5.1 channels, but sound level is always low. :(

SeeMoreDigital

1st August 2005, 09:05

Wow. :( Is there way to watch AVC/AAC rips with SPDIF output? Maybe some decoders?There were very few surround sound amplifiers manufactured with chip-set capable of on-board AAC decoding. One of them was Sony's TA-E9000ES.

Currently, when you pass AAC audio via S/P-DIF to your amplifier, the signal you are decoding is 2Ch PCM, offering matrixed (similar to Dolby Pro-Logic) style audio channels. Adding "DSP effects" will only fool you into hearing something that's not there!

If you are in any doubt, try playing this 6Ch AAC-HE "speaker test" file (http://82.2.167.237/51_Test_Encodes/AV_Setup_Tests/AAC-HE_6Ch_'Speaker_Test'.7z). Or this 6Ch AAC-LC "speaker test" file (http://82.2.167.237/51_Test_Encodes/AV_Setup_Tests/AAC-LC_6Ch_'Speaker_Test'.7z).

EDIT: The only way (I know) of listening to 6No discrete AAC channels (via S/P-DIF) is by transcoding the AAC stream "on-the-fly" to AC3, using some settings in FFdshow ;)

Cheers

AlexeyS

1st August 2005, 11:19

EDIT: The only way (I know) of listening to 6No discrete AAC channels (via S/P-DIF) is by transcoding the AAC stream "on-the-fly" to AC3, using some settings in FFdshow ;)
Can I read about this settings anywhere?

SeeMoreDigital

1st August 2005, 11:34

Can I read about this settings anywhere?

Searching is good.... This is what I found under: AAC SPDIF (http://forum.doom9.org/search.php?searchid=143606)

Cheers

AlexeyS

1st August 2005, 12:31

Searching is good.... This is what I found under: AAC SPDIF (http://forum.doom9.org/search.php?searchid=143606)
Cheers
Thanks. I only found this helpful post:

12. Is it possible to pass AAC over S/PDIF?

It is possible, although it has not yet been fully implemented. Only a few hardware devices currently support AAC decoding, and no DirectShow filter has yet been implemented with AAC pass-through ability. However, this is definitely a possibility for the future. Read more about S/PDIF and AAC hardware support here and here.

However, until AAC over SPDIF becomes more viable, there are several DirectShow filters that can be used to encode six channel AAC to AC3 over S/PDIF on the fly. Dolby Out DS filter by Haaan , as well as 1.x versions of AC3Filter can be used for this purpose. Although this reencoding on the fly process will theoretically result in a quality loss, using the full 640 kb/s bitrate allowed will result in an excellent listening experience and minimal quality loss.

So, I've downloaded AC3Filter 1.01a and it seems AAC decoder not using this filter (I've tried to make sound level higher with AC3Filter, but sound level is still the same). :(

SeeMoreDigital

1st August 2005, 12:48

AlexeyS

1st August 2005, 13:21

Actually, AC3Filter does not support direct AAC-to-AC3 transcoding. I personally asked Alexander Vigovsky if/when he was intending to include it and... it's no time soon!

Like I said earlier FFdshow does provide such a facility... you can read about it here (http://forum.doom9.org/showthread.php?p=613987#post613987) and here (http://forum.doom9.org/showthread.php?p=614511#post614511).
Ok, I've installed FFDSHOW. I see support of AAC, but when I try to inrease sound in Audio filter configuration, I don't hear any changes (even if I increase sound by 500%). It seems FFDSHOW don't decode AAC.

PS: What software players support FFDSHOW?

AlexeyS

1st August 2005, 15:31

So, it seems it's working with Windows Media Player. AC3 encoding take 4-5% of P4 3.2 GHz. The only presets of my amplifier which use 5.1 are PLII Mov and PLII Mus.

But it's not working with Nero SHowTime 2. Is this possible to FFDSHOW work with Nero ShowTime?

SeeMoreDigital

1st August 2005, 15:41

But it's not working with Nero SHowTime 2. Is this possible to FFDSHOW work with Nero ShowTime?Nope... ShowTime 2 prefers to use it's own filters!

When I tried it I used MediaPlayer Classic :)

Cheers

AlexeyS

1st August 2005, 15:52

Nope... ShowTime 2 prefers to use it's own filters!
When I tried it I used MediaPlayer Classic :)
Cheers
I don't want to use MPC, because it blurs sharp videos (espesially HDTV). Are there any mods or plugins for ShowTime?

SeeMoreDigital

1st August 2005, 16:49

I can't say I've been disappointed by MediaPlayer Classic's presentation of Hi-Def MPEG-4/AVC content. That said, you will need a speedy CPU to process any HD content... even more so if you're intending to transcode the 6Ch AAC audio to 6Ch AC3 in real time!

ShowTime 2 player can play content that it would not ordinarily play... such as VP6 or 7 or WMV: -

http://img186.imageshack.us/img186/7513/showtime2vp76ht.gif

But whether it can be convinced into using other MPEG-4 or AAC filters is unknown to me :(

Cheers