RED Epic audio out of sync when HDRx enabled

[Michael MK Siu]

Dear all,

I am having audio issues with footage shot on the Red Epic at 5k, 23.98fps, 8:1 compression.

This is running on the latest Red Epic firmware build with the audio enabled.

When playing back clips that had HDRx enabled in RedCine, the audio would slowly come out of sync. By the 3 min mark, this becomes very noticeable. Playback was done on a MacPro 3.1 2x 3.2 quad, and also through a MBP 2.66 i7, no redrocket was attached to either machine. Both machine experience the same problem.

We've transcoded prores QT (23.98, prores LT, 1280x720) from redcine and this issue is confirmed by trying to sync the audio from our external audio recorder (sound device 744T).

On the same shoot, we also have clips that did not have HDRx enabled, and these clips seem to play fine. Audio stayed in-sync until the end. Although we did have a different glitch where the audio would cut out towards the later end of the clips. But I think this is a separate issue which we are also looking into.

I've read on a different thread someone else was having drop frames issue on 25fps. I am wondering if this is a similar issue at play (Edit, added reference link here: http://www.reduser.net/forum/showthread.php?65276-25p-drop-frames)

If anyone have had similar issues or possible a fix. I'd greatly appreciate any input.

Tks,
michael

 

[Joshua Raven]

Hi there,
We have also had noticable audio playback sync issues, but only on PC. I've tried RXC Pro versions 4 thru 7 on a six core i7 with 24GB DDR3 RAM, 3GB GTX 580, OCZ Vertex SSD. Shooting 24 frame, 5:1 compression, 2:1 aspect ratio. Have all the latest drivers and codecs, tried it via HDMI out and monitoring directly off the Rampage III Etreme mobo. Also tried it on 4 other PC boxes, and it's off by varying margins, but still off. Tried it on a brand new McBook Pro and it's bang on. I've played with the audio control tab, but can't figure out how to sync it to slate. It's a little maddening, as I'm sure the solution is probably something simple. (Please don't say "The solution IS simple - use the Mac") :wink5:

 

[Michael MK Siu]

Joshua,

2 Quick questions:
1 - did having HDRx on / off affect the audio issue for you?
2 - for audio playback - is this the embedded audio track with the R3D? did you have an external audio track and was the result the same ie degree of slip.

For us, it seems when HDRx is off, there's no issue with playback. But when HDRx is on, audio slips.

And unfortunately, without a RED rocket card, I'm not able to fully figure out the margins.

I will try a PC machine that can handle Red footage tomorrow and see if the whole PC / Mac workaround will work for me...

Tks,
Michael

 

[Deanan]

1.7.9 or later is recommended for HDRx + audio.

 

[Michael MK Siu]

Deanan,

Thanks. I'm waiting to find out if we had used the beta build, or the released build.

Upon checking released notes, I see that prior to build 1.7.9, the releases have "HDRx not synchronized with audio at project frame-rates" posted. I'm wondering if you can elaborate on that, and if indeed we were on a pre 1.7.9 build, is there a way to syndronize the HDRx footage with audio - either in camera / external?

Cheers,
MK

 

[Deanan]

Deanan,

Thanks. I'm waiting to find out if we had used the beta build, or the released build.

Upon checking released notes, I see that prior to build 1.7.9, the releases have "HDRx not synchronized with audio at project frame-rates" posted. I'm wondering if you can elaborate on that, and if indeed we were on a pre 1.7.9 build, is there a way to syndronize the HDRx footage with audio - either in camera / external?

Cheers,
MK

Can you email me a frame?

deanan at red dot com

 

[Michael MK Siu]

Deanan,

What's the best way to export a frame to you - through redcine export? And which format - jpg / tiff / dpx?

Thanks!

Michael

 

[Deanan]

Deanan,

What's the best way to export a frame to you - through redcine export? And which format - jpg / tiff / dpx?

Thanks!

Michael

Use the R3D snapshot trim icon in the player. (camera with the R3D on it)

 

[Michael MK Siu]

Thanks Deanan, please check email.

 

[Michael MK Siu]

Just a quick reply to anyone that might be following the thread:

A manual re-sync base on lip movement on picture, but through my testing, the offset seems to be ~1 frame / 1 min. And the off sync is present but not noticeable until past the 3 minute mark.

Using 3 minutes segments, we can do this very mechanically and very quickly:

1. sync the audio / video on the initial slate
2. starting that point, cut the video footage into 3 minute segments;
3. shift the audio segment back 3 frames (or video forward 3 frames) / each segment
4. continue shifting until the end of your video clip.
(ie, for segment 2, audio and video be 3 frames different; for segment 3, it should be a 6 frames difference - shift x 2, etc. etc.)

This can be done in matters of minutes, and works well upward to a 30 min clip (that's the longest sync piece I have).

Of course once in post, sound editor will need to go in and tighten it, but for offline editorial, this resolves everything for now.

Using the 1.7.9 / 1.7.10 firmware is RED official response for HDRx sync (and they were able to provide any help with footage shot on previous firmware...). In testing, 1.7.9/1.7.10 syncs HRDx video and audio, but 1.7.9/10 is still beta and I'd suggest doing some test shoots to ensure the firmware didn't "break" anything else before committing to it. Even if it becomes an official release, I'd still recommend some testing before upgrading since their release notes are not very detailed with what's changed / upgraded.

 

[Marc Wielage]

So the segment starts out in sync, then starts slipping over time? This is an interesting problem.