LAV Filters - DirectShow Media Splitter and Decoders

[nevcairiel]

Originally Posted by e-t172

I already gave you three links.

Yeah, and i like spending my sundays reading pages of documentation on a topic which is totally irrelevant to the point.
Just to repeat the point:
LFE mixing is disable by default, and anyone that enables it can set the value to whatever he deems correct. This is even in accordance with the Dolby spec you cited, in fact directly after you quote:

Since the inclusion of this channel is optional, any downmix coefficient may be used in practice.

In practice, the user can configure the coefficient they think sounds the best. And with that, the discussion is over. Its the users choice. I made a choice for the default, anything else is totally up to them.

[kitame]

just give the kid the candy he wants, up the limit to 2.5 >,> but leave the default settings to either 0 or 1.

also can i ask for a master volume with a gain boost? like 200% or so, so i can lower the master control of the soundcard a tad lower, as it is i need to up the volume from 30% to 40% from the master control even if MPC is set to 100%.
or simply put i want MPC to sound louder than the other sound sources set at the same level.

[SeeMoreDigital]

Well said Nev

[Andy o]

Originally Posted by kitame

just give the kid the candy he wants, up the limit to 2.5 >,> but leave the default settings to either 0 or 1.

also can i ask for a master volume with a gain boost? like 200% or so, so i can lower the master control of the soundcard a tad lower, as it is i need to up the volume from 30% to 40% from the master control even if MPC is set to 100%.
or simply put i want MPC to sound louder than the other sound sources set at the same level.

That's a recipe for disaster (clipping). The Windows mixer doesn't only provide multichannel downmixing, it also lets you change relative volume of applications, which would be a better fix for you. The only reason I would use digital gain (carefully) is if I got audible hiss from the amplifier at the volume I listen to.

[mzso]

Hello nevcairiel!

I was wondering, do you think AMD's HSA will have any sort of interest for multimedia coding/muxing/processing.

[kitame]

Originally Posted by Andy o

That's a recipe for disaster (clipping). The Windows mixer doesn't only provide multichannel downmixing, it also lets you change relative volume of applications, which would be a better fix for you. The only reason I would use digital gain (carefully) is if I got audible hiss from the amplifier at the volume I listen to.

the problem though is that a number of my applications doesn't have any volume controls even under windows mixer which makes them run at 100% all the time, which really does force me to change the master control all the time and windows mixer isn't so friendly with setting them at these precise numbers making it harder =/.

[Andy o]

Strange, I've never seen that. If the application's sound is going through the mixer, the control should be there, which applications are these?

[DragonQ]

Originally Posted by nevcairiel

Yeah, and i like spending my sundays reading pages of documentation on a topic which is totally irrelevant to the point.
Just to repeat the point:
LFE mixing is disable by default, and anyone that enables it can set the value to whatever he deems correct. This is even in accordance with the Dolby spec you cited, in fact directly after you quote:

Surely the default mixing coefficients should be the coefficients used as "standard"? I mean, that's what you've done with the front and surround channels, why should the LFE be any different? The +10 dB thing is why the LFE channel is always much quieter than the others (when you look at it in an audio editing program). It's so that there's more dynamic range for loud bass thumps.

Originally Posted by nevcairiel

In practice, the user can configure the coefficient they think sounds the best. And with that, the discussion is over. Its the users choice. I made a choice for the default, anything else is totally up to them.

As I understand it, the user can't currently choose the standard +10 dB level right now so that needs fixing. The default level is up to you but I'd have thought implementing the most commonly used setting would make the most sense.

I understand that most PC speakers shouldn't be receiving LFE since they can't handle the frequencies, so maybe you could have the default being 2.24 but then a tickbox saying "mix LFE" that is off by default and greys out the slider? That way users that want LFE can just tick the box and get the correct setting, rather than having to research what the correct setting actually is. Or, have "suggestions" written underneath the sliders?

[nevcairiel]

Originally Posted by DragonQ

Surely the default mixing coefficients should be the coefficients used as "standard"?

0 is a perfectly fine standard, as i said earlier, a recommendation by Dolby to not mix LFE into stereo for two reasons: To avoid clipping issues that may arise from mixing even more channels into one, and secondly because a lot of weak stereo systems just don't do low frequencies.

For the slider, it'll remain as-is and there won't be an extra checkbox. I already changed it to accept a higher range of values (up to 3.0).

The problem with the additional dynamic range on the LFE channel is that when you increase the volume by +10dB in the digital signal, you either may get clipping on those "loud bass thumps", or the overall volume of the other channels reduces as clipping protection is engaged, so ideally the volume should be changed as the last step, possibly in the analog domain.
If you use a normalized matrix and set a 2.24 coeff for LFE, the volume of all other channels will be *significantly* reduced, so i would never recommend that. If you don't use the normalized matrix but clipping protection instead, it of course depends on how strong the LFE signal really is, but if that 10dB extra head room is actually used, it may also result in a significant volume loss in the middle of an action scene.

Anyway, in theory there always are "perfect" settings, in practice however the "standard" just has a lot of drawbacks.
The 10dB offset was introduced to allow retaining the full dynamic range in the other channels, while giving the LFE channel a chance to have more volume. If you downmix with that 10dB taken into account, you basically just revert this advantage and reduce the dynamic range of all other channels - thats just not even close to "perfect".

Anyway, i really don't want to spend more time discussing this. I increased the configuration scale, and you can configure it to whatever you think is perfect.
Every minute i spent here arguing, is one minute i cannot spent on developing stuff, so i'll go back to developing stuff.

[bugmen0t]

Is there a way to set all levels to the same defaults like ffdshow, ac3filter, etc. without using a registry hack? (i.e. center = lfe = 1/sqrt(2), surround = 1) With the sliders i cannot achieve accurate values. Probably even hitting exactly 1 gets difficult now with the expanded range.
Is there any intention to make lav audio sound differently than other filters? (lfe = 0 is fine too, of course)

[kitame]

Originally Posted by bugmen0t

Is there a way to set all levels to the same defaults like ffdshow, ac3filter, etc. without using a registry hack? (i.e. center = lfe = 1/sqrt(2), surround = 1) With the sliders i cannot achieve accurate values. Probably even hitting exactly 1 gets difficult now with the expanded range.
Is there any intention to make lav audio sound differently than other filters? (lfe = 0 is fine too, of course)

giving it a type box would make it easier, so typing in the number you want will be easier than sliding randomly.

Originally Posted by Andy o

Strange, I've never seen that. If the application's sound is going through the mixer, the control should be there, which applications are these?

they're emulators.

[DragonQ]

Originally Posted by bugmen0t

Is there a way to set all levels to the same defaults like ffdshow, ac3filter, etc. without using a registry hack? (i.e. center = lfe = 1/sqrt(2), surround = 1) With the sliders i cannot achieve accurate values. Probably even hitting exactly 1 gets difficult now with the expanded range.
Is there any intention to make lav audio sound differently than other filters? (lfe = 0 is fine too, of course)

You can use the left/right arrows on your keyboard. That usually lets you get to exact values with sliders.

[egur]

Originally Posted by CruNcher

would it be enough to replace the beta Media SDK .dll with the older one (official driver, or just put the older into the lav splitter dir instead directly) to get it back working or is it a deeper issue ?

I'm afraid the problems are across the board.
I've released a new version that should handle the current problems. It has more robust code so I recommend using it on production drivers. Also fixed some a/v sync issue (not relevant to LAV filters).
For LAV to work with the new DLL under the problematic driver, it needs to disable most of the multithreading features (e.g. just keep MT copy). I hope Nev will not produce such an ugly workaround. A dialog with QS options in LAV would be nice for testing purposes though...

[strumf666]

In some movies I get upsampling and upmixing on audio; can this be disabled somehow? I am bitstreaming audio through HDMI to AV receiver.

[Andy o]

If you're bitstreaming, LAV is not upsampling. What you're seeing there, the "output" information, is normal for bitstreaming DTS-HD. If there is any upmixing that you're having is not from your PC, it's from your receiver.

[strumf666]

Regarding the channels you are correct , I can see it on the AVR that it is being fed only 5.1 (and the receiver is upmixing it to 7.1), so the info display in potplayer seems to be broken (or I don't understand why it doesn't show same as source). Regarding the sample frequency I can not see it on the receiver so I can not verify it.

Another test with a DD 2.0 source:


And regular DTS:


edit: Another question - The aspect ratio and output resolution differs in all three screenshots is that normal/bug as well or have I set something wrong?

[Andy o]

If you're bitstreaming, it's simply not upsampling. There's no way it can even do that (besides decoding->upsampling->reencoding, which is impossible with DTS-HD right now).

Re: aspect ratio, it seems your player is set to somehow stretch horizontally to screen width, which I assume is 2048 pixels. There's no option to preserve original AR?

[strumf666]

Both my screens are the standard 192x1080 so I am not really sure why the stretching.
Or is it a bug again? I don't seem to remember having noticed the non-matching output until I started using lav+madvr in potplayer. Now I am not sure if the problem is with potplayer od madvr and/or lav.

[Andy o]

Can't just switch players and test? I think most of us are using MPC-HC.

[nevcairiel]

This is a failure in PotPlayers OSD. Most video decoders will output it as 2048, because the renderer asks for that (better alignment). However, the extra pixels are empty padding and the renderer will not show it. Don't trust such an OSD at face value if you don't know how to interpret it properly