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conforming 23.98fps to 25fps and audio pitch correction
I’ve just had a horrible experience attempting to conform a documentary shot and edited in 23.98 (XDCam EX1) to 25p for an eventual 1920×1080 50i broadcast.
Conforming the timebase is super easy using Cinema Tools, but then of course the audio is pitched up by nearly a semitone to remain in sync… which I and the producer didn’t want. So I attempted to use Soundtrack Pro to timestretch the original four, pre-conformed, pre pitched up audio channels to fit the new, shorter final edit length but remain in their “native” pitch. It was a total nightmare and I basically failed. I could attempt to describe the various things I tried and the various results I got but it would just take too long and I would get too angry (lol), but the main issue was “close but no cigar”… would start out in sync but by the end of the 23 minute doc, soundbites would be a good half second or more out… or sometimes the timestretch would be way too severe. Sometimes using the pullup/pulldown function would pitch the audio up (not desired), other times it would appear the audio tracks became the correct length but when I exported the audio, it appeared that the timestretch functions were not applied into the export.
I’d really just like someone’s opinion on how to best approach such a problem so in future. Have any of you had to deal with this? How have you done it?
Jon
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6 Replies
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A search here at the Cow would have answered your question.
https://forums.creativecow.net/thread/8/1114109#1114162
https://forums.creativecow.net/thread/8/1106997#1107009
STP is a toy, not up to this sort of task. As I have pointed out in these past posts, I am not a fan of the speed up. Duration, edit timing and music tempo are also sped up and unless you have the right tools, the audio pitch is either uncorrected or gets crunched badly
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Thanks Michael. I did search extensively as it happens, and found different posts which didn’t really answer my question, but I was using search using terms such as “23.98 to 25 conform” and so on, I probably should have thrown a PAL and an NTSC in there too but never mind.
I agree, I am not a fan of speeding up the edit either, and STP does not appear to be up to the task. What I was hoping for was a “you should have done it this way” response, but if you’re saying that the only way to do this properly is with specialist hardware, then I don’t feel so bad about failing on this one.
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The only way I’ve known this to be acceptable is by doing the pitch shift in real time using a hardware pitch shifter like the Lexicon 2400. This is a device that runs concurrently with the picture in real time and outputs a pitch-shifted signal exactly relative to the speedup or slowdown of your video. Other than that (or similar high quality hardware), I’ve never known software plugin effects to be up to the task, and always consider them to be sort of proxy previews of what it will sound like (but never final quality output).
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so in other words, perform a pitch-shift on the post-confrormed audio, retaining that audio’s overall length? yeah that sounds like it could work, and surely with this approach I wouldn’t encounter any timing problems over the 23 minutes of the doc, just a slightly artificial sounding warble on the audio… the conform from 23.98 to 25 results in a 0.7 semitone increase in pitch I believe? So it would simply require a pitch down of 0.7 semitones to compensate?
Thanks all for your responses. I feel better about this now :p
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Dave is right. A simple approach is to pitch correct the sped up sync audio. But using the software I mentioned in previous posts (and again below).
I often find people struggle with search here at the Cow and usually the culprit is using complicated search strings.
Mark – it has been a long time since I did real time pitch with a Lexicon. However, software like MPEX3, Pitch N Time and now iZotope do absolutely amazing pitch/ length correction, particularly holding phase on 5.1 mixes and stems. The software is as good if not better. I used to find the Lexicon had a bit of a warble on sustained music notes. Unless they have improved their processing, all the software I mention does a cleaner job without those artifacts.
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Thanks Michael. I haven’t done this in a long time as well and always remembered the software plugins to pale in comparison. Glad to hear there’s good stuff in CPU land for this.
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