Weird audio spike/hiccup when rendering MP4 video

tom-m9741 wrote on 5/17/2017, 7:53 PM

I'm currently searching for a new video editor to suit my needs, so I downloaded the trial version of Movie Studio Platinum 14. I've been really enjoying its smooth performance so far, and I'm thinking it might be the one I'm looking for, but there is a problem: whenever I try rendering an MP4 video, there's a half-second audio spike at the start of the rendered video file. It's rather distracting, and I can't figure out what's causing it or how to prevent it. There's no sign of any audio spike in the preview before rendering, not audibly or on the bus meters. I tried using two methods for rendering: first I tried doing "Render As > Sony AVC/MVC > Internet 1280x720-30p". I then tried doing "Make Movie > Save it to my hard drive > MP4". Both outputs had the aforementioned audio spike at the start, though they were slightly different from each other. Any ideas as to what might be happening?

(For the record, I also tried rendering a WMV version of a video and there was no audio hiccup, but the visual quality was noticeably decreased.)

Comments

EricLNZ wrote on 5/17/2017, 8:39 PM

Does your project contain audio right at the start? If so what source file is it.

Also check you are using the latest Build 122.

NickHope wrote on 5/17/2017, 9:27 PM

Just tried a "Render As > Sony AVC/MVC > Internet 1280x720-30p" render in Platinum build 122, based on Sony RX100 m2ts footage, and didn't see an audio spike.

EricLNZ wrote on 5/17/2017, 10:41 PM

Yes I cannot reproduce it either Nick which makes me wonder if it's something in the source.

tom-m9741 wrote on 5/17/2017, 11:06 PM

Does your project contain audio right at the start? If so what source file is it.

Also check you are using the latest Build 122.

My project consists of a 720p .mp4 video clip (with its audio muted in the timeline), and an .m4a / MPEG-4 song audio clip laid over it separately, set to start at the very beginning of the timeline. It's in the very brief moment of silence before the first note of the song begins that the audio spike is heard in the rendered output. That's what made it stand out so much; the moment the spike happened was supposed to be nothing but silence.

Also, I just checked and it is indeed Build 122.

NickHope wrote on 5/18/2017, 1:07 AM

So try and narrow it down to just the .m4a clip (by deleting the video clip and re-rendering). Then share that on a cloud service so we can try it, if you're allowed.

tom-m9741 wrote on 5/24/2017, 10:28 PM

So try and narrow it down to just the .m4a clip (by deleting the video clip and re-rendering). Then share that on a cloud service so we can try it, if you're allowed.

Thanks to this recommendation, I think I figured out what was causing the problem. In the render options I had, the sample rate for the audio was set to 48,000 Hz. I tried rendering at lower audio sample rates instead (44,100 Hz and 32,000 Hz), and the audio spikes disappeared. In short, decreasing my audio sample rate eliminated the spikes somehow.