the first version does not have ctl
as per the reference you linked, they should do exactly the same

as for the sync issue
it's probably nvidia's hdmi implementation
try asking here

how much is it out of sync ?
48000/44100 times or less ?

That's an interesting question. I can't determine that by eyeballing it. What do you recommend trying?

And, I checked again: the nested version and the three-line versions are not the same. The nested version has no DMix, and the three-line version has DMix. The reference that I linked to does claim (or at least clearly imply) that they should be the same, but there's an earlier section about syntax that directly contradicts that. It's the section about syntax that seems to be correct.

good to know
in this config it is explicitly stated what the output card will be, and that dmix is a plug used for the !default output

anyway
to test, something like
play -n synth 30 sin 347
where synth 30 means synthesize for 30 sec
and a stop watch to measure real time
or a video where you pick a sync time by a sound/video frame as a keypoint

Oh btw, I've seen this in guides for other distros:

It doesn't work on Slackware. Does anyone know why?

Here's another "the nested format with the exclamation point throws out the rest of the PCM section; the inline format overrides only the exact keys listed" post:

http://www.mail-archive.com/alsa-use.../msg26200.html

I wonder if this is the "hardware issue" that's causing my A/V sync woes:

HDMI's Lip Sync and audio-video synchronization for broadcast and home video

Trying Pulseaudio now. Interestingly, the A/V sync seems to be a lot better (so far).

Yep. Hardware issues. It just started happening with Pulseaudio.

I have just started reading this thread to try to get pulseaudio set up. I'm running slack 14.1 64 bit, but not running a multilib setup. I like pulseaudio as it's easier to switch back and forth from my laptops built in sound to my usb headset. I can get my usb headset to work by putting this in .asoundrc in my home folder.

pcm.!default {
type hw
card LX3000
device 0
}

ctl.!default {
type hw
card LX3000
device 0
}

I've noticed that I don't get sound when watching videos in chrome or chromium. I'm not into games and don't use skype, but is there a setup for pulseaudio? I know that it's possible for them to work, as other distros use pulseaudio and it is easy to switch between the internal sound card and usb headset with no issues.

I installed pulseaudio, pavucontrol, and alsa-plugins from sbopkg. When I run this command - /usr/bin/start-pulseaudio-x11 - I get the error below.

$ /usr/bin/start-pulseaudio-x11
N: [pulseaudio] main.c: User-configured server at {e667ecc9de8aeb375cf7fafa544c03f1}unix:/tmp/pulse-bCoMUIyY8gg2/native, which appears to be local. Probing deeper.
Failure: Module initialization failed

Please try changing that (in its entirety) to:

Earlier in this thread (it should be on the same screen), I covered how that's different. If that doesn't work for you, then use the card number and not its name.

As for launching Pulseaudio, all I did to launch it was run the executable called "pulseaudio" after starting X; as I was running OpenBox, I put "pulseaudio &" in ~/.config/openbox/autostart.

I finally got pulseaudio working and using this below in my .asoundrc has sound playing from chromium again.

pcm.!default {
type hw
card LX3000
device 0
}

ctl.!default {
type hw
card LX3000
device 0
}

I don't have the default sound working on my laptop as of yet, but the main hurdle is over and I can watch videos on chromium!

Many thanks.

I'm going to do a little more research and see if I can get the sound working on my laptop. but that's not as important.

Nvidia Audio Driver Support
 

I'm not sure where I found this URL, but decided to repost it here.

HDMI Audio on NVIDIA GPUs
Stephen Warren, for NVIDIA Linux Support <linux-bugs@nvidia.com>
version 8, 2014-03-04

ftp://download.nvidia.com/XFree86/gp...ysical_devices

In addition to running through this trouble shooting guide, I also realized that my 4k HDMI Monitor (TV)'s speaker settings were causing audio problems as well.

Check your sound settings.
- Turn off Surround Sound - Temporarily
- Turn off Audio Leveling - short test wav files may not be audible with this on.

E Net Arch

I've since replaced the video card, and the A/V sync over HDMI (using Pulseaudio) is now perfect.

So it does appear that the A/V lag was caused by a bad HDMI port on my previous video card.