We strongly suspect that FCP interprets / converts audio sample rates to either pull up or pull down audio to a target khz rate. This "help" is applied when you import a true 24fps 48khz stereo pair bounced from a Protools 24fps session. We suspect FCP likes to think 24fps audio is actually 23.98 audio, although frame rate should not matter for audio.
We are working in a true 24 fps sequence--not telecined material, not video material, not drop frame. The media has no bearing--all digital Quicktime files w/ no pulldowns--all real 24fps. Just have to make that clear.
Steps to replicate this bug:
1) Start w/ 24FPS FCP timeline. Not a 23.98 timeline. Export a self-contained or quicktime reference file and a separate multi-track OMF. Reimport and sync in a native 24 FCP timeline--just to check.
2) Mix w/ OMF & QT ref in Protools (current version OSX), bounce to a 24fps stereo pair AIFF 48khz. No brainer for 29.97.
3) Import AIFF output back to original FCP timeline. Audio is early or fast. A green render bar appears when brought into original 24fps timeline. When the AIFF is put in a 23.98 timeline, green bar disappears or FCP thinks a true 24fps originated track is a 23.98 file.
Audio references were checked against original sequences: all match perfectly as expected, eliminating the culpability of the reference files given to the audio mixer. Audio mixer finds OMF syncs perfectly with Quicktime timeline references in Protools session. Everything appears to be 24fps in Protools. Output 24p AIFF bounce is re-imported to Protools to check 24p-ness. It syncs fine.
4) If the above is true, changing the speed of the 23.98 file to 99.9% will yeild correct sync, pulling up a 23.98 file to 24fps. We've found this corrects the speed differential & timeline sound syncs.
5) Re-output any varying rate AIFFs from Protools again (47952, 48000, 48048, 50000 khz) and import into original FCP 24fps timeline. All run the same speed and time--and should NOT. In the FCP bin, FCP recognizes the sample rate, but in the timeline, it ignores sample rate differences by converting on the fly to 48khz.
BIG PROBLEM if you work @ digital 24fps.
Also have tried re-referencing AIFF 24fps 48000 file by running it thru many different media programs & outputting to bring new file into FCP. Still thinks it is 23.98.
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