Sync all over the place

[Mark Spano]

[Gary] “FCP always wants 48k 24bit audio regardless of where the audio ( and or video) came from.”

A note of clarification: FCP can handle 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz audio at 8, 16, or 24 bits – both as imported files and as sequence settings. The sequence setting should, however, be largely dependent on the output hardware – most third-party cards like KONA support 48kHz ONLY at either 16-bit or 24-bit (which is probably what your stance is referring to). You can choose this in the Audio MIDI Setup utility if you want to configure KONA for 16-bit I/O.

When using audio in an FCP sequence, FCP can render it to whatever the sequence setting is, but does an audibly less good job than Compressor or DAWs like Pro Tools. But you can absolutely use any of the above combinations of bit rate and sample rate source files in FCP. In Paul’s case, 16-bit/48kHz audio rendered to a sequence setting of 24-bit/48kHz would not noticeably affect the sonics, as all FCP would be doing is adding bits at the bottom of the signal.

There’s a lot to be said about how FCP handles audio in the FCP manual. This section copied below might enlighten:

Choosing Audio File Sample Rate and Bit Depth
Final Cut Pro can import audio with any bit depth and sample rate supported by QuickTime and Mac OS X Core Audio. Final Cut Pro performs real-time bit depth conversion and sample rate conversion when your audio file settings don’t match your sequence settings. However, less processor power is required when your audio file settings and sequence settings match.

Choosing Sequence Bit Depth
The bit depth setting in the Sequence Settings window determines the bit depth whenever you output or export your sequence. However, sequence audio is always mixed using 32-bit floating-point values.

[Sam Tollitt]

the sync issue is one thing but…

I am also a bit confused re 24 bit audio…. I was approached about an audio issue the other day and I recommended that it be 16bit 48Khz for best compatibility with FCP, are you saying this is incorrect?

I have just loaded a ton of sequence presets in fcp 7 as I was a bit worried & they all read 16bit 48Khz as expected, if it is the case that I am wrong could somebody please explain why?

back to the point > I have also experienced the sync issue on a vast number of systems, it has been boiled the problem appearing to be something to do with FCP 7 & kona cards.

multiple drivers have been tryed and konas have been swapped out in place for BM cards.

anyone experiencing the same problems? I’m sure there is as it does appear to be a solid issue which we cannot rid of!

[Gary Adcock]

[Sam Tollitt] “I have just loaded a ton of sequence presets in fcp 7 as I was a bit worried & they all read 16bit 48Khz as expected, if it is the case that I am wrong could somebody please explain why? “

Ok this issue has been in FCP since it was KeyGrip, it is a rendering mismatch.

While FCP can and does read mixed frame and audio rates there is a catch- the master audio and your timeline settings need to match bit depth.

If you digitize into FCP using hardware all of the defaults go with 24bit audio.
If you use the default easy setup presets for ProRes it wants to SEE 24bit audio.

If you load something else in that timeline, like files with 16bit audio, the RT extreme engine keeps on rendering that audio content whether there is content in the timeline or not – because you chose a 24bit audio setting in the preset and you are using 16bit audio that was converted from something else.

So every time you hit a gap the renderer jumps ahead to the next clip to render, even though you are not to that point in the timeline yet.

if you Mixdown your audio or if you set the SAFE RT you should not be seeing these issues.

Try rendering out the file completely to a self contained QT with a Audio Mixdown- this should all go away.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Gary Adcock]

[Mark Spano] “A note of clarification: FCP can handle 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz audio at 8, 16, or 24 bits – both as imported files and as sequence settings.”

FCP claims it can handle HDV, AVC Intra and R3D files, but they will not play at all if the timeline settings are not correct. That is the problem here, a settings mismatch that is only affecting the audio

What FCP can do and what it does are often 2 different things.

I got $20 USD that Mixing Audio bit rates is the cause.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Paul Harb]

Hi Gary,

So I did what you said and exported the audio file at 24bit 48k and brought it back in…..still out of sync AND if I lay that MASTER audio down that I will be cutting to, with my camera scratch track it drifts, also I tried turning off all RT to safe and changed my timelinesettings to 24bit 48k…. it didnt fix it. Here is something that has been brought to my attention today. The audio playback that was used for the band to lip sync to was a 44.1k file 16bit. We ran that camera at 23.98fps. Is there no way that this is the issue? And just to be clear I do appreciate your help.

Paul Harb

Paul Harb-Producer/Director
Wrong Beach Multimedia
Dual 3.2 GHz Quad/10.5.5/8GIG RAM/FCP 6.0.4/QT 7.5.5

[Gary Adcock]

[Paul Harb] “So I did what you said and exported the audio file at 24bit 48k and brought it back in”

I have never said you needed export your audio timeline as 24bit.

“still out of sync AND if I lay that MASTER audio down that I will be cutting to,”
if it was out of sync when you exported it will still be out of sync, changing to 24 bit will not fix that.

NOTE that FCP / Media Mangler / Compressor all do really lousy Audio Conversions — do this in STP or better yet Protools to have this handled properly.

You need to fix the issue in the timeline FIRST before trying an export. -did you try an audio mixdown inside of FCP?

Does your ALL of your audio match the timeline settings? that would mean EVERY piece of Music, VO’s, SOT and Foley audio.

Where did you get the audio and how was it converted to Aiff?

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Gary Adcock]

[Paul Harb] “Here is something that has been brought to my attention today. The audio playback that was used for the band to lip sync to was a 44.1k file 16bit. We ran that camera at 23.98fps. Is there no way that this is the issue?”

Nope that should not be an issue, that is standard CD quality.

and Stop thinking that changing the timeline will do anything for this issue.

MIXDOWN THE AUDIO within FCP- if that does not show promise- then something else is screwed up.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://blogs.creativecow.net/24640

[Paul Harb]

To be clear again…..there is no different sources of audio, it is a music video……I have scratch tracks on the camera from a playback AIFF file that was played on set for the band to lip sync to. I am cutting the picture to the same audio AIFF track that was played on set. A mixdown will not help as there is ONE source of audio in my timeline, the master AIFF that was played on set and that is also heard as a scratch track by the cameras. That said I tried a mixdown and it didnt fix it.

If i lay down the scratch camera audio on the timeline and sync it with the AIFF master that was played to the band and heard in the camera scratch track, it drifts slowly throughout the song and by the end is out of sync.

Paul

Paul Harb-Producer/Director
Wrong Beach Multimedia
Dual 3.2 GHz Quad/10.5.5/8GIG RAM/FCP 6.0.4/QT 7.5.5

[Paul Harb]

There is nothing to mixdown, it is ONE source of audio….that said I did a mixdown and it did not fix the issue. It is something else. The telling sign to me is that if I lay down the scratch audio track from camera with the AIFF master track that Im cutting to and that is being heard in the camera scratch track it should stay in sync throughout however it drifts….isnt this a pulldown thing?

Paul

Paul Harb-Producer/Director
Wrong Beach Multimedia
Dual 3.2 GHz Quad/10.5.5/8GIG RAM/FCP 6.0.4/QT 7.5.5

[Mark Spano]

[Paul Harb] “isnt this a pulldown thing?”

Can you check the RED files again? Was that actually shot at 23.976 or maybe it was shot at 24fps?

I don’t think it’s a pulldown issue though because you said this:

[Paul Harb] “Its out of sync, I stop it….its back in sync…then goes out again….”

which led me to my initial comparison to the slot/bandwidth issue on the card. Try this: set your external video to OFF. Play your sequence. Does it still drift? If so, it’s NOT the card. If not, then it’s the card.