Frame Accuracy when editing in FCP6 at DVinfo.net

Andrew Wilson · December 19th, 2007, 02:56 AM

I've been editing my first HD project - it's a docu that someone else shot with the JVC100 or 110. They digitized the footage using the HDV codec and sent me the drives. It's my first exposure to HD post.

I edit with FCP 6.0.2 on an 8 core mac and I'm finding that a lot of the edits don't seem to be frame accurate. I mark my in based on dialog and it seems like when I play back after the edit, it's sometimes a couple frames off.

I'm wondering if that's an artifact of editing HDV long GOP codec.

If I get myself an EX1 - will I have similar issues?

I imagine I could transcode to an I-frame codec like prores422 but the files are so much bigger and it adds a step, I'm trying to make tapeless LESS work.

Anyone else having frame slippage when editing dialog with their EX1?

Chris Forbes · December 19th, 2007, 11:50 AM

speed /spid/ [speed] -noun, verb, sped or speed·ed, speed·ing.
–noun
1. Editing SD video on an 8 core mac

—Synonyms 1, 2. crazy fast

I have never seen anything like what you describe editing EX1 footage.

Andrew Wilson · December 19th, 2007, 08:03 PM

yeah... this machine is a little quicker than my old quicksilver.

I'm on my way to check the JVC forum but in the meantime, has anyone seen this type of behavior editing the JVC HDV codec. The stuff was shot 24p if that makes a difference at all.

So Chris, it sounds to me like when you're editing with EX1 footage, the edits sound exactly as you intended and don't seem to slip once edited in, right?

Andrew Wilson · December 19th, 2007, 09:02 PM

I'm editing my first HD project for someone who shot with the 110, captured using HDV 720 codec and then he sent me the drives. The footage was shot in 24p and I'm editing using FCP 6.0.2.

Sometimes when I'm editing, specifically sound, the edits don't seem to be frame accurate. I'll set an in point, do the edit, and the sound is off by a couple of frames when I play back the edit in the sequence. It only happens sometimes and usually to work around it, I'll actually re-set an in-point that's a couple frames away from where it should be (based on the waveform).

Has anyone else had an experience similar to this?

Thanks!

Chris Forbes · December 20th, 2007, 11:46 AM

Correct, I have not had a problem at all. And I don't encode into anything else I just import and edit.

Eric Pascarelli · December 20th, 2007, 12:45 PM

The clips work perfectly in FCP without any conversion.

FCP deals with the GOP's very elegantly. I am not sure exactly what it is doing internally, but if you lay a clip down in the timeline that was not cut exactly on a keyframe, FCP renders the required frames before and after the cuts, allowing you to cut at any frame.

If you look at the render status bars along the top of the timeline you can see that they are pale blue instead of grey at the beginning and end of most clips - these blue areas are the part that FCP has rendered.

This seems to happen automatically and instantly when you place a cut clip in the timeline.

Steve Oakley · December 20th, 2007, 11:52 PM

the problem is when FCP 6.0.2 can't play something in RT, it loses audio sync. It keeps playing the audio, but never figures out its lost a few video frames hence what you are seeing. stop play, then play and sync will be good. its yet another FCP bug.

Andrew Wilson · December 21st, 2007, 10:02 PM

That's not what I'm experiencing. I'm editing dialog and even looking at the waveform, I'll set the in point at silence. After the edit is made and I play it back, the edit actually upcuts the sound. It's like it's not editing at the point I set. This is my first time editing something that compressed with MPEG GOP and I can't help but think that's part of the issue somehow.

I'm not setting points on the fly and the edit sounds wrong no matter how many times I stop and playback.

I've experienced what you're talking about but with an 8-core and 5 gigs of ram it's usually with many layers and graphics involved when using SafeRT.

Steve Oakley · December 22nd, 2007, 12:32 AM

what's happening it not normal. first rule of FCP weirdness is trash the prefs - the prefs file, obj cache, plist. yes all your settings will be reset but FCP should be back to normal.If you don't have FCP rescue to automate saving, deleting and replacing prefs, just google it. I'd also recommend zapping PRAM as another painless quick-fix.

did you or some one else change the audio playback offset ? by default it should be set to 4. I would not recomend changing it.

if you continue to have problems.

1. if you are using a 3rd party video card, reinstall drivers, make sure they are the latest

2. ditto for 3rd party audio I/O

2B. is it possible the clips were slipped out of sync & relocked

2C. have you verified the source clips play out of the camera / deck in sync ?... it happens

2D. are your clips and the FCP TL in a compatible Timebase / FPS ?

3. failing this, reinstall FCP & QT, update

FCP edits mpeg2 correctly, been doing it since 5.x so its something in your setup / install. that said I have not been too pleased with 6.0.2 and its playback. you might want to try a backgrade to 6.0.1

Andrew Wilson · December 23rd, 2007, 01:34 PM

Thanks for the tips. It only happens on this one HDV project and everything else I do is SD miniDV.

and it only happens on a couple of clips - other clips work fine. I'll check some more things based on your suggestions and get back.

thanks!

Steve Oakley · December 23rd, 2007, 03:03 PM

if its only happening on a couple of clips, try reloading the clips. it sounds like something is weird with the media file. I know with Prem Pro if you capture over a really bad long drop out, the audio after that point will be out of sync.

Andrew Wilson · January 8th, 2008, 12:55 PM

Update to this post:

(using FCP 6.0.2)

When logging my footage, I digitize whole segments of an interview and then place markers and label the markers based on what they're talking about. I don't convert the markers to subclips.

If I double-click the marker in the bin and edit from what appears in the viewer then my audio is out of sync.

If I open the actual master clip and skip ahead to the segment I want and edit from there, then the audio is fine.

So in other words, if I'm editing from a marker segment, the edits are off but if I edit right from the master clip, I'm fine.

December 19th, 2007, 02:56 AM	#1
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	Frame Accuracy when editing in FCP6 I've been editing my first HD project - it's a docu that someone else shot with the JVC100 or 110. They digitized the footage using the HDV codec and sent me the drives. It's my first exposure to HD post. I edit with FCP 6.0.2 on an 8 core mac and I'm finding that a lot of the edits don't seem to be frame accurate. I mark my in based on dialog and it seems like when I play back after the edit, it's sometimes a couple frames off. I'm wondering if that's an artifact of editing HDV long GOP codec. If I get myself an EX1 - will I have similar issues? I imagine I could transcode to an I-frame codec like prores422 but the files are so much bigger and it adds a step, I'm trying to make tapeless LESS work. Anyone else having frame slippage when editing dialog with their EX1?

December 19th, 2007, 11:50 AM	#2
Chris Forbes Regular Crew Join Date: Mar 2006 Location: Salt Lake City, Ut Posts: 155	Found this in the dictionary speed /spid/ [speed] -noun, verb, sped or speed·ed, speed·ing. –noun 1. Editing SD video on an 8 core mac —Synonyms 1, 2. crazy fast I have never seen anything like what you describe editing EX1 footage.

December 19th, 2007, 09:02 PM	#4
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	Frame Accuracy when editing in FCP6 I'm editing my first HD project for someone who shot with the 110, captured using HDV 720 codec and then he sent me the drives. The footage was shot in 24p and I'm editing using FCP 6.0.2. Sometimes when I'm editing, specifically sound, the edits don't seem to be frame accurate. I'll set an in point, do the edit, and the sound is off by a couple of frames when I play back the edit in the sequence. It only happens sometimes and usually to work around it, I'll actually re-set an in-point that's a couple frames away from where it should be (based on the waveform). Has anyone else had an experience similar to this? Thanks!

December 22nd, 2007, 12:32 AM	#9
Steve Oakley Trustee Join Date: Apr 2006 Location: United States Posts: 1,158	what's happening it not normal. first rule of FCP weirdness is trash the prefs - the prefs file, obj cache, plist. yes all your settings will be reset but FCP should be back to normal.If you don't have FCP rescue to automate saving, deleting and replacing prefs, just google it. I'd also recommend zapping PRAM as another painless quick-fix. did you or some one else change the audio playback offset ? by default it should be set to 4. I would not recomend changing it. if you continue to have problems. 1. if you are using a 3rd party video card, reinstall drivers, make sure they are the latest 2. ditto for 3rd party audio I/O 2B. is it possible the clips were slipped out of sync & relocked 2C. have you verified the source clips play out of the camera / deck in sync ?... it happens 2D. are your clips and the FCP TL in a compatible Timebase / FPS ? 3. failing this, reinstall FCP & QT, update FCP edits mpeg2 correctly, been doing it since 5.x so its something in your setup / install. that said I have not been too pleased with 6.0.2 and its playback. you might want to try a backgrade to 6.0.1 Last edited by Steve Oakley; December 22nd, 2007 at 01:06 AM.

December 19th, 2007, 08:03 PM	#3
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	yeah... this machine is a little quicker than my old quicksilver. I'm on my way to check the JVC forum but in the meantime, has anyone seen this type of behavior editing the JVC HDV codec. The stuff was shot 24p if that makes a difference at all. So Chris, it sounds to me like when you're editing with EX1 footage, the edits sound exactly as you intended and don't seem to slip once edited in, right?

December 20th, 2007, 11:46 AM	#5
Chris Forbes Regular Crew Join Date: Mar 2006 Location: Salt Lake City, Ut Posts: 155	Correct, I have not had a problem at all. And I don't encode into anything else I just import and edit.

December 20th, 2007, 12:45 PM	#6
Eric Pascarelli Major Player Join Date: Nov 2007 Location: Los Angeles, CA Posts: 498	The clips work perfectly in FCP without any conversion. FCP deals with the GOP's very elegantly. I am not sure exactly what it is doing internally, but if you lay a clip down in the timeline that was not cut exactly on a keyframe, FCP renders the required frames before and after the cuts, allowing you to cut at any frame. If you look at the render status bars along the top of the timeline you can see that they are pale blue instead of grey at the beginning and end of most clips - these blue areas are the part that FCP has rendered. This seems to happen automatically and instantly when you place a cut clip in the timeline.

December 20th, 2007, 11:52 PM	#7
Steve Oakley Trustee Join Date: Apr 2006 Location: United States Posts: 1,158	the problem is when FCP 6.0.2 can't play something in RT, it loses audio sync. It keeps playing the audio, but never figures out its lost a few video frames hence what you are seeing. stop play, then play and sync will be good. its yet another FCP bug.

December 21st, 2007, 10:02 PM	#8
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	That's not what I'm experiencing. I'm editing dialog and even looking at the waveform, I'll set the in point at silence. After the edit is made and I play it back, the edit actually upcuts the sound. It's like it's not editing at the point I set. This is my first time editing something that compressed with MPEG GOP and I can't help but think that's part of the issue somehow. I'm not setting points on the fly and the edit sounds wrong no matter how many times I stop and playback. I've experienced what you're talking about but with an 8-core and 5 gigs of ram it's usually with many layers and graphics involved when using SafeRT.

December 23rd, 2007, 01:34 PM	#10
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	Thanks for the tips. It only happens on this one HDV project and everything else I do is SD miniDV. and it only happens on a couple of clips - other clips work fine. I'll check some more things based on your suggestions and get back. thanks!

December 23rd, 2007, 03:03 PM	#11
Steve Oakley Trustee Join Date: Apr 2006 Location: United States Posts: 1,158	if its only happening on a couple of clips, try reloading the clips. it sounds like something is weird with the media file. I know with Prem Pro if you capture over a really bad long drop out, the audio after that point will be out of sync.

January 8th, 2008, 12:55 PM	#12
Andrew Wilson Tourist Join Date: Nov 2007 Location: Vermont, USA Posts: 123	Update to this post: (using FCP 6.0.2) When logging my footage, I digitize whole segments of an interview and then place markers and label the markers based on what they're talking about. I don't convert the markers to subclips. If I double-click the marker in the bin and edit from what appears in the viewer then my audio is out of sync. If I open the actual master clip and skip ahead to the segment I want and edit from there, then the audio is fine. So in other words, if I'm editing from a marker segment, the edits are off but if I edit right from the master clip, I'm fine.