Sync problems

I produced a 6 segment TV series 21 years ago using Betacam SP as my media. I recently bumped the footage to a Sony digital tape deck and then captured it in FCPX. Each segment has a TRT of about 22 minutes. After capturing a 22 minute segment the lip sync gradually drifts until it is out of sync in a major way.

When I capture this same segment using my old FCP-7 on a Power Mac everything remains in sync. I much prefer using FCPX for re-editing this series so I am requesting assistance to determine what I am doing wrong if anything.

I am using FCPX on an iMac.

Thanks in advance for any assistance.

What digital tape deck? What are the complete specs of the media? How did you capture in FCPX?

If you can capture in 7, why don't you capture there and edit in X?

Audio sync drift over time is usually due to mis-matched sample rates. What sample rate is the tape? What sample rate are you capturing at? My guess is FCPX is not adjusting the sample rate properly. FCPX tape capture support is minimal, and I hate using it for that. Use QT Player or FCP 7, like Tom suggested.

FCPX.guru wrote: Audio sync drift over time is usually due to mis-matched sample rates. What sample rate is the tape?...

Betacam SP was an analog format, with video data striped helically and the audio recorded longitudinally. Being analog there was no sample rate per se, but obviously the capture board must sample that. It's interesting the audio and video drift apart over time, but not if captured on FCP7 on the PowerMac.

Like Tom said, if it can be captured while maintaining sync on the PowerMac, why not just transfer that file to the FCPX machine? If the old PowerMac doesn't have network access and no USB port, maybe that's the problem. It probably has a Firewire port, else how could the video be captured. If nothing else is available, borrowing a Firewire hard drive might necessary, then finding a newer Intel Mac with a Firewire port. It is probably faster to solve the file transport problem than to solve the sync drift problem.

Edit/add: there might be a byte-ordering difference (so-called big endian vs little endian issue), but I've never transferred data between a PowerMac and Intel Mac, so I'm not sure: developer.apple.com/library/content/docu...ts/ByteOrdering.html

Thanks everyone. I greatly appreciate your input. I finally answered my own question by checking the box that indicates "Fix audio problems" while importing. My 22 minute segment is in perfect sync to the very end.

In the future I shall read the small print.

All the best and Happy New Year!!

Tape is digital, not analog, and relies on audio sample rates. I come from the tape era, and yes, audio had a sample rate on Beta tape.

FCPX.guru wrote: Tape is digital, not analog, and relies on audio sample rates. I come from the tape era, and yes, audio had a sample rate on Beta tape.

The OP's question was about Betacam SP, an analog video format. Audio in Betacam SP is recorded two ways: channels 1 and 2 are recorded longitudinally using analog with Dolby C noise reduction. Channels 3 and 4 are recorded using analog FM and striped with the video frame. The video signal was recorded as component analog using CTDM multiplexing. More details: betacam.palsite.com/format.html

By contrast DV tape was truly digital for both audio and video. It encoded audio at either 48k or 32k samples/sec.

Betacam became digital in 1993 with Digital Betacam which finally replaced the analog Betacam SP. Digital Betacam used four digital audio channels encoded at 48Khz using PCM.