Cineform Aspect HD HDMI capture: sound out of sync

[Alex Raskin]

First seconds are fine, but about 1 min into the video, the sound starts going ahead of video, significantly.

What's the reason and how to prevent/fix this?

Aspect HD 4.3.2 build 77 with HDMI Intensity card was used. No issues were reported or visible during live recording from V1U camera. The sound sync issue was discovered later in post.

[Alex Raskin]

Additional tests show that sound in fact seems to be on-target, but it's the video that starts lagging behind.

The test was made against the reference video made in DV on a different camera, simultaneously with V1U.

In post... if I sync V1U-HDMI-AHD recorded *sound* with the DV video, it stays sync'd all the way to the end of the 3-min. segment.

However the V1U's *video* starts lagging significantly about 1min into the segment.

This is despite the fact that V1U's video and audio come from the same file and are supposed to be synchronized in the first place.

Post is done with PPro, but even watching the original Aspect HD avi video in Moonligh-Elecard player shows the same out of sync 1min in.

Is this a known issue?

[David Newman]

Is your PC keeping up on playback? This is not a known issue, sound sync has been tested with the V1U to be fine. Try setting your PC into Accelerated playback mode (in AHD v5 it is the tools folder.) Also are you removing pulldown or not? Either way we are not dropping video frames or audio packets, the capture engine doesn't have the concept -- a dropped frame is a bad capture, we never drop frames just to "keep up", but it is possible to have a system that is underpowered. How is the CPU load during encode? If there are no dropped frames and all audio is there, where is the sync issue coming from? However, we have seen one PC with a PCI-e bus that causes the Intensity card to drop frame before our engine sees the data -- on that machine the bus saturated at 29fps. 1920x1080 4:2:2 at 30Hz, is close to the limit on the single PCI-e on some systems. At times like these test your PC filming a metronome, look for missing frames capture to uncompressed to confirm that CineForm is not introducing it -- if we are we need to know ASAP, but no one has reported this.

[Alex Raskin]

The PC specs are as follows:

mobo: Supermicro X6DA8
processor: Intel Xeon 3Ghz HT
memory: 2Gb DDR2-400

It has 2 PCI-e slots, first one (x16) used by the graphic card.

Second one (x4) used by my intensity HDMI card.

Now, I measured the PC's Performance and discovered it to be as follows:

- The system uses about 50% of CPU cycles in idle mode (no applications loaded) - which is obviously wrong in the first place. I'm trying to determine why is this happening. (No, it's not the Intensity card.) (In Processes view, System takes 30% of CPU cycles; System Idle Process another 70%; no other processes are running; but CPU usage at the same time is reported as 50%.)

- When either Intensity's own app or Cineform's HDLink is running, CPU usage hits 100% consistently - which surely is not good (The respective app hovers around 98%, while System Idle Process goes down to 1% or disappears, and so does the System.)

- Intensity's MediaExpress app recording to MJpeg has even faster and more severe desync between the recorded video and sound than Aspect HD has

NOTE!
Intensity's app has HDTV 1080i 59.94 recording mode that I used (since the 24p video I shoot is interplexed into the 60i signal, this mode seems to be the one to choose.)

However, Aspect HD, while opening a video preview window for DeckLink, defaults to HD1080PsF 29.97 mode - is this normal?

I do set Aspect HD to do 3-2 pulldown, but I'm still unsure if this is what I'm supposed to be doing to extract 1080p24 AHD avi?
/end NOTE

Please answer the Aspect HD setting Question above; by then, I will probably resolve the CPU cycles issue and will re-try the HDMI capture again and report to this thread.

Thanks!

[David Newman]

Yes, you want 3-2 pulldown set. When you are preview in HDLink the CPU usage will be high as it basically capturing before you press start -- CPU load will not change to much between capture and preview, however 100% usage is not good.

[Alex Raskin]

CPU usage: I'm now assuming that my 3Ghz Xeon is not enough, and since the mobo accepts two processors, the second one is now on order to increase CPU power.

I'm hoping this will rectify the issue; will report here when I receive and test the second processor.

Here's my AHD capture setup with Intensity - see screen capture below.

Its' strange to me that Aspect forces Intensity output to 1080 29.97P while in fact it is capturing a 60i video (well, 24p intertwined into the 60i stream...)

Again, the idea is to capture 24p as comes out of Sony V1U via HDMI into the PC running Aspect HD 4.3.2 that removes 2-3 pulldown on the fly, leaving me with the pure 24p (23.976 actually) Aspect HD avi file in 1440x1080.

Just wanted to make sure this is not something I'm doing wrong with the capture settings ?

[David Newman]

Alex,

I didn't realize that you had the old Xeon, even with two CPUs that can be trouble. While each core can be fast, their access to memory is extremely poor. You do have a 800MHz front side bus so that will help, but we have not tested old Xeons in any configurations for the Intensity. When we first didn't live capture via HDSDI we only recommended AMD Opteron, and now with Intel Core 2 proc, pretty much any dual core will do it. I hope you are not spending too much for that second CPU if doesn't work.

Those settings should be fine.

[Alex Raskin]

Well, I have no options at this point but to install the ordered Xeon and see what happens.

Since the computer actually works - albeit out of sync - with one processor, I'm hoping the second one will do the trick.

Yes, memory throughput worries me, but I can't do anything about it right now.

I'll let you know either way.

Thanks for your support.

[Alex Raskin]

Ta-da!!

With the second Xeon processor, CPU load is just over 50%, and both video and sound are recorded fine, in perfect sync now. (Tested for about 3 min, no time for the longer tests right now...)

So I'm very happy at the moment :)

Thank you David

[David Newman]

That is awesome news, and your Xeon system is performing better than I expected, a very nice surprize.