huge difference in volume between bitstream and PCM

[tony359]

Hello all

I am experiencing an issue when using MPC-HC with madVR.
My little mediaplayer unfortunately does not support HD formats over HDMI so I am forced to disable them under the audio filter so they get decoded on board and sent to the receiver in PCM.

I have noticed that there is a huge difference in volume (about 10dB) whether I use PCM or DTS - not DTS-MA, old fashioned DTS.

Basically if I select a DTS-MA track and I tell the audio filter that my player is NOT compatible with DTS, it gets decoded and the receiver sees a PCM-multichannel stream. If I put a check on DTS on the audio filter, then the DTS core is sent via HDMI - as the system tells the player that my HDMI port cannot handle the full stream. The receiver says "DTS" on the display.

Whenever I switch to DTS the general volume is much higher and I have to lower it approximately 10dB to match the PCM volume.

I discovered that when I watched a movie with a badly made DTS-MA track (lacked dynamic) and I had to switch to DTS to enjoy it properly.

I was wondering whether this is a known issue or maybe something 'normal'?

Thanks!
Tony

[huhn]

PCM volume can be altered by the player bit stream audio (without reencoding) is always 100 % volume.

so if the player/windows is not at 100% volume bit stream audio should be louder.

[tony359]

Hi,

Thanks, I did not know that. However I have checked all the volume controls and they are all maxed out. PCM is still much lower than bistream. Anywhere else where I could check?
Thanks

[huhn]

i just recommend you to stay at PCM only.

have a look here:
windows general mixer
windows app audio mixer
audio driver
media player

the next possible problem could be that your AVR is apply DRC to bitstreamed audio which makes it louder it is pretty common and of cause lowers audio quality.

[tony359]

I did check under control panel/sound and in the windows mixer. All seems maxed out. I'll check again. Sure I stay on PCM - until my system can handle HD formats.
My receiver is an Onkyo preamplifier (no amp) which is supposed to be very good quality. I did check on the menus and could not find DRC enabled - or any DRC option for what matters.

But it's nice to know it's not supposed to happen so I'll check more, there must be a reason for that.

Thanks again for your help.

[huhn]

well they mostly do this without an options. they simply do it all the time.

there is nothing wrong with PCM anyway.

[tony359]

that's interesting. I have found the DRC option (Late Night) but only works in AC3. On any other formats it says "not available".

I have tested my laptop, its HDMI supports DTS-HD. Same issue, so we know it's not a setting on my media-player - or at least it would be quite bizarre as on my laptop I never use MPC-HC so everything is basically factory default.

I've also noticed that the LFE is about 10dB louder when in bitstream. I did notice some discrepancies in the past and I was going to do some tests. The AVR has a selectable LFE level for each format (0, -10, -20). Not too surprised if I think of how the LFE is played back in cinemas.

You now planted the seed of doubt in me about the Onkyo constantly applying DRC on bitstream. As I said it was $2000 at the time, semi-professional pre-amplifier only receiver. I'd be very disappointed to know that it's compressing my sound. I can try on forums - but it's an old AVR. I've done some tests and once the level is adjusted the dynamic seems the same to me though. I guess if I am really fussy I could test the outputs using an oscilloscope while playing some PCM sinewaves?

I've always used that AVR with a PS3 which is not supporting HD formats over HDMI - converted into PCM first - so probably the issue has always been there and I simply never noticed that...

Edit: oh well, it's not just me. I probably never noticed as never played bitstream. Weird anyway, I usually don't miss those details ;) Now I also understand why my LFE level was massively loud while in bitstream - I calibrated it in PCM ;)

http://www.avsforum.com/forum/90-receivers-amps-processors/881652-onkyo-google-page-ranking-sc885p-preamp-thread-31.html#post12450509

re-edit: the user who posted that is now telling me it was a player issue and that he's still using the 885 with no issues. I can only go and try the PS3 now but it takes time to switch between PCM and bitstream, I'll have to use my mike to record and analyse.

[tony359]

Right, I managed to do some tests today.
First, I did not remember that the PS3 could handle HD formats on HDMI!

I first tried The War of the Worlds - DTS-MA. Same exact levels between HD and PCM on PS3. Then I moved to MPC-HC and levels were still fine, no difference between tracks. So this is definitely content related.

Then I tried a more recent title: Transformers: age of extinction. Dolby TrueHD.
With this I had a minor level change on the PS3, about 4dB. On MPC-HC the change in level was much more obvious, usual 8-10dB.

I did notice something when the HD format kicked in on the AVR: "Dial Norm: +4dB" appeared for a second. That, if not mistaken, is a metadata that tells the receiver to turn the volume up 4dB.

Any chance that:

1. Dialogue Normalisation is not happening on PCM - either PS3 nor MPC-HC
2. There is a bug with the dialnorm in MPC-HC and somehow it is applied twice as much on bitstream (I forgot to check what the dialorm said on the MPCHC) or somehow PCM level is reduced by the same amount? I did some further tests tonight and indeed PCM seemed to be 8dB softer under MPC-HC

Any thoughts?
Thanks
Tony

[huhn]

when bitstreaming the data isn't touched. it is not possible to change it at all.

with pcm anything changes.
if you are suing sanear it could be the limiter of sanear that is lowering the audio or the down mixing if applied.

i'm pretty sure meta data is ignored for most of the part. DRC cna be "meta data" too.

[tony359]

Thanks. I am using the default renderer - I'm not sure if it's sanear, I'm opening the LAV audio decoder to set the settings.
Is there another one I can try to see if it behaves differently?

[tony359]

anybody?

[clsid]

Audio renderer:
MPC-HC options > Playback > Output

An alternative decoder would be AC3Filter.

[tony359]

Thanks.
Just a silly question: how do I know which is working? I happened to have AC3Filter on my main PC but how does that interact with the LAV audio decoder? Are they two separate things? 'cause both control panels have effect on sound if I change parameters. Thx!

[raffriff42]

AC3Filter has its own normalization and dynamic range controls. You probably want to disable (un-check) them.
While the track is playing, click the AC3Filter icon in the Windows system tray, or in MPC*: right-click, filters, AC3Filter.
Main tab, DRC unchecked.
Mixer tab, Auto gain unchecked.

[clsid]

AC3Filter will process the PCM output from LAV Audio (or any 0ther decoder). If you don't want that then disable PCM on the System tab in AC3Filter settings.

[tony359]

Thanks raffriff42. I have indeed disabled those nasty settings :)

clsid, I'm a little confused. Who is doing the decoding here?

[clsid]

If LAV AUdio is being used during playback, then that is what does the actual decoding.

MPC-HC menu > Play > Filters

[tony359]

Hi all again.
I'm resuming this conversation as I now have a video card that does bitstream but I will have to move back to PCM soon as I'd like Dirac EQ on the PC and that will require a PCM stream.
I was hoping to improve on the sound quality/level consistency and I now have the concern that I am not really listening to uncompressed DTS-MA and Dolby-TrueHD but only to their cores- this is what a quick search brought up.

I would be happy to purchase a decoder if that helps. I want to use a player that works with madVR - as I want the 3Dlut calibration.

Can someone please confirm that I am indeed decoding the lossless streams using LAVfilters or AC3Filter and/or recommend a good quality alternative?

Thanks!

[nevcairiel]

LAV Audio decodes both TrueHD and DTS-HD MA perfectly lossless. AC3Filter does not.

[tony359]

Thanks,

Now I have bitstream capabilities, I'll do some LFE level test, maybe with some measurements. Have you heard of LFE level inconsistencies before?

Thanks for your time on this!
Tony

[chros]

Hi all again.
I'm resuming this conversation as I now have a video card that does bitstream but I will have to move back to PCM soon as I'd like Dirac EQ on the PC and that will require a PCM stream.
I was hoping to improve on the sound quality/level consistency and I now have the concern that I am not really listening to uncompressed DTS-MA and Dolby-TrueHD but only to their cores- this is what a quick search brought up.

I would be happy to purchase a decoder if that helps. I want to use a player that works with madVR - as I want the 3Dlut calibration.

Can someone please confirm that I am indeed decoding the lossless streams using LAVfilters or AC3Filter and/or recommend a good quality alternative?
I also came from software decoding and using with 4 analog speakers couple of years ago. When I bought my AVR, I also wanted to stick to the old habits (ac3filter, ffdshow audio filters in the chain, etc). After fiddling around a lot (and always braking something), I ended up with a minimalistic design: everything is handled by the AVR.
- only necessary filters in the chain
-- audio splitter (LAV) -> decoder (LAV) -> internal audio renderer (MPC-BE/HC)
- in the above players:
-- system defalt device, exclusive mode, bypass windows mixer
-- disable everything in the built in audio switcher

In this way, the AVR properly handles everything:
- bitstreaming
- recognizes DPLII encoded 2ch audio as well (e.g. with aac, flac, etc.)

...level consistency...
Also trust your AVR with this.

Edit: Oh, and this is my 1000th post here, I have to open up a bottle of wine right away! :)