Audio sync problems when screen set to 24 Hz (2 Viewers)

[gibman]

It is a 23.976 fps xvid clip.
audio is mp3 (stereo) / ffdaudio decoder- outputting to spdif port on my amplifier.

I do not have 24hz capability on my dev rig ..

/gibman

I did a bit of fooling around with my new hd4770 card in CCC 3d settings.
if I put " wait 4 vertical synch" to "always on", then 24 fps based material on 24hz will go quickly out of synch.

Again if I put it back to ATI default, which is "off.unless app specifies", then all is good again.

Odd result as it should be exactly the same when application specifies the v-sync enabled (as MP does always).

- Was the clip real 24hz video file (or actually non-24hz clip, like 23.9xxx)?
- Were you using SPDIF / HDMI ( audio also )?
- Does the bug go a way (when v-snc is forced) and you use analog audio or decode the audio to stereo mode with some audio codec?


Is this a driver issue on ATI side? At least Arcsoft player has had similar effects with ATI and 24Hz + Blu-ray (just search AVS forums).

This issue is caused by multiple different issues (like the users have already reported).

• Audio codec issue
• Driver issue (with forcing v-sync on), maybe HDMI audio & video gets out of sync?
• Bug in drivers (as 24 vs 23.9xxx setting as display frequency solves the issue)
• Bug in MP

ps. now as we have one developer (gibman) who is able to reporduce the issue we might be closer to the solution (in case it is a MP bug)

/gibman

 

[tourettes]

It is a 23.976 fps xvid clip.
audio is mp3 (stereo) / ffdaudio decoder- outputting to spdif port on my amplifier.

Now we need to test few things.

1) use analog audio cables (to rule out the SPDIF)
2) use 23.9xxx refresh rate instead of the 24hz (this solved the issue on some Nvidia users).

I do not have 24hz capability on my dev rig ..

At least you have a test PC where you can trigger the issue

 

[frankwaan]

2) use 23.9xxx refresh rate instead of the 24hz (this solved the issue on some Nvidia users).

Are there devices capable of doing that?

 

[tourettes]

2) use 23.9xxx refresh rate instead of the 24hz (this solved the issue on some Nvidia users).

Are there devices capable of doing that?

Well, every TV set that says it is 24p compatible must support t he 23.9xxx refresh rate as almost all blu-ray releases are 23.9xx and not 24hz. I don't know why the marketing people are again mixing things up. 23.9xxx and 24 are different thing, althou they are pretty close to eatch other

 

[frankwaan]

2) use 23.9xxx refresh rate instead of the 24hz (this solved the issue on some Nvidia users).

Are there devices capable of doing that?

Well, every TV set that says it is 24p compatible must support t he 23.9xxx refresh rate as almost all blu-ray releases are 23.9xx and not 24hz. I don't know why the marketing people are again mixing things up. 23.9xxx and 24 are different thing, althou they are pretty close to eatch other

OK, but we also have videocards mixed in... Mine (9400GT) states it outputs 24Hz (not 23.976), which results in my TV stating it plays at 1080P24... Indeed a bluray (or bluray rip) plays 23.976FPS... Could our problems start here and we have to use reclock afterall? How do the standalone bluray devices cope with this?

 

[rak]

Does ATI really output at 24Hz? Reclock helps to smooth video, but it does not solve this issue. I tried to decode DTS nd ffdshow and then encode it back to DD in reclock and output to SPDIF, but this also does not help. So this mean, that reclock did not solve the out of sync issue. It only helps with stuttering.

Interesting is, that exactly the same effect happens when I jump to the middle of a movie (not FF) - where the audio is 1-2s out of sync (like if I would watch the movie to this point). I do not know, how the spliter and codecs works, but it looks like they use different clocks

 

[frankwaan]

Does ATI really output at 24Hz? Reclock helps to smooth video, but it does not solve this issue. I tried to decode DTS nd ffdshow and then encode it back to DD in reclock and output to SPDIF, but this also does not help. So this mean, that reclock did not solve the out of sync issue. It only helps with stuttering.

Interesting is, that exactly the same effect happens when I jump to the middle of a movie (not FF) - where the audio is 1-2s out of sync (like if I would watch the movie to this point). I do not know, how the spliter and codecs works, but it looks like they use different clocks

That's true, in my experience reclock only works to smoothen the picture, but that was when the automatisch refresher wasn't supported yet, and I always had my TV set to 50Hz... Now it automaticly sets te refresh rate to 24hz which plays 23.976fps stuff smooth already.

As I read it from you, reclock doesn't help in resolving the sync problems either. So that gives still no work arounds

 

[rak]

I've checked the VSYNC option in CCC but I already have "off unless application specifies" and the audio sync problem exists.

 

[jet70]

Tourettes, you are absolutely right.

The problem with my xvids seems to be audio drift after stepping forward through the file.

If I leave it to play, the sounds remains in sync.

What is intersting though, is that the sync when stepping forward through the file only drifts when the refresh rate is 24hz!!!

Just thought I would make this point and make people aware.

Might this problem be easier to fix? - it is very frustrating!

Thanks.

 

[CypherMK]

Hi folks,

I've fixed the problem. At least in my case. I switched from EVR to VMR9 in mediaportal setup. Now I don"t get audio sync issues anymore. Used renderers like coreavc and powerdvd9. Both work flawless.

Switching to VMR9, also fixed my MPC-HC audio sync issues.

Hope it helps.