Quote My issues are that my camera Panasonic GH4 audio and external recorder Rode NTG-2 microphone using a pre-amp USB mixer and recording with Audacity, saving as wav files, do not "Sync by Audio" in PD IF the clips are short. Example, the syncing usually works perfect if the audio clip is longer than three seconds. But, if the audio is shorter than 3 seconds long, it will usually never match up with the GH4's recorded audio.

Here's my hallucination about how the audio syncing works, why short clips fail, and what might work better for you. I don't have special insight into how the audio syncing algorithm is written, but having done some work like this in spam identification, I have a pretty good guess. You can't just do a slice by slice comparison of wave levels between two clips because any interference (like echo within a building) will throw that right off. Instead, a statistical "color map" is derived from the reference audio (your long clip). The clip to be placed is run through the same algorithm which then asks the question, "What part of the color map is this second clip the most similar to?" This means that the decision is made as a matter of statistical significance, not exact matches. Therefore, there can be error.

I believe the reason short clips fail is that their statistical fingerprints are a little less developed and can therefore match up with more areas in the color map of the reference audio. Further, the statistical certainty over any of those potential matches is lower.

The solution? Well obviously, longer clips to match to the reference will help. I have good results that way. But what if your clips are unavoidably short? Just reduce the size of that "color map" so that there are fewer potential match points. Go to your reference audio clip and take a good guess where the proper positioning of the second clip will be. Now temporarily shorten that clip by dragging in the edges to isolate your approximate match area. Then do your audio syncing! Once you get placement, restore the original bounds to your reference audio clip.

I'll say that this has helped me but it's also true that I've had few opportunities to do it as I put lots of pad on both ends of almost anything I'm recording.

Len

Are you expanding the timeline to the maximum, You can expand the timeline to frame level. One frame is 33 ms at 30 fps, 40 ms at 25 fps.

3 seconds would be 90 frames at 30 fps. Or 75 frames at 25 fps. Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.

Len,

Thanks for the response. But, I have tried that and have not seen success. I think I'll try to remeber at recording short clips to just make them extra longer, and say something very clear towards the end of it so it can have an easier time matching up with the software.

Quote Are you expanding the timeline to the maximum, You can expand the timeline to frame level. One frame is 33 ms at 30 fps, 40 ms at 25 fps.

3 seconds would be 90 frames at 30 fps. Or 75 frames at 25 fps.

Yes, I did max it, but its still not going to save me any time right? Have to sync the audio on my own?

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Quote Are you expanding the timeline to the maximum, You can expand the timeline to frame level. One frame is 33 ms at 30 fps, 40 ms at 25 fps.

3 seconds would be 90 frames at 30 fps. Or 75 frames at 25 fps.

Yes, I did max it, but its still not going to save me any time right? Have to sync the audio on my own?

Yes, you are.

It is not as hard to sync when the timeline is expanded. You can sync within one frame or about 33 milliseconds if your video is 30 fps. Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.

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Quote Are you expanding the timeline to the maximum, You can expand the timeline to frame level. One frame is 33 ms at 30 fps, 40 ms at 25 fps.

3 seconds would be 90 frames at 30 fps. Or 75 frames at 25 fps.

Yes, I did max it, but its still not going to save me any time right? Have to sync the audio on my own?

Yes, you are.

It is not as hard to sync when the timeline is expanded. You can sync within one frame or about 33 milliseconds if your video is 30 fps.

I only would be willing to do this on small clips, cause sometimes even long clips do not work with syncing. I have to find away around this as I mentioned, will probably just re-record the small 2 seconds clips and make it 10 seconds saying something clear towards the end of the clip so it syncs up with everything. Then, I can trim it down to 2 seconds after its synced!