Re: FCPX: STRANGE AUDIO ECHO EFFECT ON CUSTOMIZING CLIP SPEED

I had to speed up an interview clip, customized to 115%. Now I have a disturbing echo effect in the audio. Any way to fix this? Thanks a lot for helping

What is the format of the interview clip?

Best wishes,

Ronny

Hi Ronny,

it is a ProRes422 .mov file, transcoded from mts with 5DtoRGB, sound was on-camera.

Best
L

As the clip has been converted to ProRes, the artifacts you hear cannot come from the audio compression. So my guess is that the artifacts come from noise that has been introduced during the recording. Such noise can be practically inaudible when the clip is played at normal speed, but any speed changes above 2 to 5% will enhance the audio artifacts due to resampling.

Unfortunately there is not much you can do unless you can clean up the audio before applying the speed change. Do you have a professional denoising plugin such as iZotope RX Advanced? If not, how long is that clip?

Best wishes,

Ronny

Thanks for the quick reply Ronny. But I think it is not a problem of noise.It delays the speaking voice, it comes over double now (very low volume)!

Hi Lucian,

Thank you for sending me the file. I have retimed the interview using a professional retiming plugin. I think it sounds a lot better now. I have sent you the file via e-mail. You can add it under your retimed video clip in FCP X, they should match up perfectly.

Best wishes,

Ronny

Thanks Ronny, that worked perfectly. Looks like from certain percentage on (in this case it was 115%) this disturbing phenomena begins to appear.
I did others speedups before, customized at lower speed (100,4%) like described in an older thread, without these kind of problems.
Cheers

Hi Lucian,

Yes, that's correct. Audio retiming usually works without many problems up to 10%. As soon as you go beyond 10%, the resampling may cause audible artifacts depending on the complexity of the audio (background noise, music etc...). In such cases you need specialized plugins or dedicated software that can analyse the audio clip and filter out any unwanted noise before processing the main audio.

Best wishes,

Ronny

I have another question about retiming.

I work mainly with transcoded mts files, shot in 24fps progressive (Panasonic Lumix). As I am shooting an environmental-musical film, I sometimes use the GoPro for some strange looking fun shots. These are 30fps as far as I know. I tried to convert them before through the automatic option in the retimer, didn't work. They still do no run smooth. What am I missing?

Are you working in a 24fps timeline or in 25 fps?

Retiming GoPro footage can be very quirky because of the high compression. You could try optimizing the clips to ProRes before applying the Automatic Speed in FCP X.

If you want you can send me a small GoPro clip so we can see how you can solve this.

Best wishes,

Ronny

OK, I will send you 2 short GoPro clips which are not running smooth. I have a 24fps timeline/storyline.
In fact I did not transcode them or optimized them before.

Great. I am in the studio right now. So I will have a look at them as soon as I get them.

Best wishes,

Ronny

I have sent you 2 short clips which are not running smooth through WeTransfer. Exported as mov file.

For anyone who is following this thread: the problem got solved by using the "Automatic Speed" option in the FCP X Retime menu.

Best wishes,

Ronny

Ronnie – good to know – and thank you for posting the solution.
JR