Choppy Video using HDMI Audio

[PCRHitman]

Hi, i'm wondering if anyone else has had this issue and if so might know the root of the problem.

I have recently upgraded my TV to a 47" Panasonic 3D jobby (TXL47FT60B).

In doing so, I've had to upgrade by graphics card to support HDMI 1.4 so I've moved from an old GeForce 7900GT (DVI -> HDMI converter) to a 610GT (HDMI -> HDMI) (cheap and cheerful I know, but this isn't a gaming rig my any means)

The spec of the PC for reference is an i3, 4GB Ram, 60GB SSD.

with the old 7900GT the audio came via optical from the on-board sound chip, and it would play extremely high quality video (17GB mkv files) passing DTS-HD straight through to the AV receiver without a glitch.

Now I thought i'd move to using HDMI audio, but playing the same video it stutters (not in the way that a loss of bandwidth would stutter, its just glitchy). (BTW i'm using VLC and MPC to test this). I normally use MPC for these things, but to check that there wasn't an issue with MPC i installed VLC and everything played smoothly, it was then that i noticed i hadn't set up VLC to pass through the audio to the receiver. As soon as i told it to do this, the played started to glitch.

Now i had the same problem using the onboard HDMI (intel HD onboard graphics). What do you think it might be? could it be that the cheap 610GT just doesn't had enough bandwidth to cope with that amount of data or something else?

I haven't yet reverted back to using the optical for audio to prove my theory but i will be doing that tonight after work.

thanks in advance!

 

[Make]

What resolution and FPS do you run the TV at?

I am thinking your old HDMI cable might not be up to the grunt.

HDMI cable versions do not matter, but there is such a thing as "high speed" and a regular one when you go over to 120hz and stuff.

Or maybe it's just a dodgy cable.

 

[Drangueos]

Well I had a problem like this...
I have a laptop just to watch movies... before I was using my sound system to play the audio via the audio connector.

Then tried to use only the HDMI to play the sound direct on my tv and it stutters, I found out that when "converting" the audio to HDMI my CPU was getting a higher usage. (my cpu was a Sh..t AMD v120 single core) I replaced the cpu for a Phenom II triple core and now it plays flawless.

I also use VLC.

OR

your cable.

 

[imginy]

The only times I have had choppy audio is when the pc is down clocking it self either cpu or gpu.

I would make sure your gpu isn't bouncing off idle you may have to set a custom profile and turn the clocks up a bit.

 

[Orch]

Not sure if this relevant to your circumstances, but I was plagued by tiny stutters for ages for figuring it out.

It was down to the source file being 24p, but the TV trying to play it at 50hz. The conversion (I can't remember the techninal name, 'pulldown' maybe?) just wasn't smooth.

As soon as I got the TV to adjust it's frame rate to 24hz it was silky smooth.

This was using XBMC media player. Not sure if your change of cables would have the same effect of changing the way the TV behaves, but might be of some help maybe.

 

[PCRHitman]

Thank you all for your replies!

There are a number of things here for me to try, although I think I can logically rule out a few.

I doubt it will be my CPU, the i3 has plenty of power for my needs, plus when not using HDMI audio everything is fine I would think that the load on the CPU is pretty much the same in both cases. (however will get monitor it just in case).

I have bought a new cable just in case, however its the same type of cable as the one I use to connect my PS3 which plays 3D blu-rays fine (case and point, star trek into darkness in 3d, stunning quality blu-ray!)

with respect to the different refresh rates, I would assume this isn't the case (although I do believe it is relevant) as the video plays smooth without HDMI audio.

What's odd, I was watching a 720p Video last night, only 1gb file but audio in Dolby 5.1 and this stuttered.

When i receive my new cable and more investigation has been done i will post my findings.

 

[famasfilms]

with the old 7900GT the audio came via optical from the on-board sound chip, and it would play extremely high quality video (17GB mkv files) passing DTS-HD straight through to the AV receiver without a glitch.

Optical and Coaxial SPDIF don't carry HD audio as they don't have the bandwidth.

I have several downloaded films that say they are encoded in DTS-HD, these are carried by coaxial to a receiver that doesn't support HD audio decoding, the signal still lights up with "DTS" which suggests that they also have a regular DTS audio track encoded.

 

[Make]

Well, on the optical they do carry multichannel audio, it just compressed. However people say they cannot hear the difference between compressed and uncompressed, when compairing to HDMI.

Uncompressed optical audio is PCM, but that's 2-channel.

 

[famasfilms]

optical/coaxial can carry regular Dolby Digital and DTS.

They do not have the bandwidth to carry Dolby Digital HD or DTS-HD

 

[PCRHitman]

optical/coaxial can carry regular Dolby Digital and DTS.

They do not have the bandwidth to carry Dolby Digital HD or DTS-HD

Thanks for this, I was aware that HDMI had more bandwidth but didn't know optical didn't support DTS-HD (which is daft really considering you can fit most of the worlds information down a single optical cable). But now when i play DTS-HD my AV received now says DTS-HD MSTR so i will be endeavouring to get my HDMI to work properly.

I do believe i have fixed the problem though. I've upgraded to windows 8.1, and thus reinstalled everything. Now my 3D works with powerDVD (previously it did not) and with the latest k-lite codec pack it seems to be working fine now. I've also changed to having my video decoded by the graphics card, don't know if this is what fixed the issue though as the CPU was only peeking at 17%

 

[Drangueos]

Good that you fixed