So after two days of getting pissed off and about to file a ticket to get my mic checked out and repaired i decided to one more test.
This test had me go back to the video the same time the poping shows up in my audacity line up.
To my surprise the poping is not in the original .mp4 file recorded by OBS. After doing some more digging my only conclusion is it is audacity. This is futher proven that i made a OBS recorded muted the mic ( Blue yeti) And the spikes where still in the audio even when there is no audio.
I have lost many videos to this noise that ive been able to slightly fix through leveling it all out but i would like to know what is causeing this problem to avoid it in the future.
No Both my Audio and Video is recorded in OBS through a 1-3 track system 1. mixed 2. mic 3. Game. I then Import the audio int audacity for editing and cleanup. However in the past few weeks it’s been adding those spikes in there even when their not in the .mp4 file when i go to that same timestamp.
All i’m wanting to do is to find out why audacity is adding audio spikes that don’t exist into the files and how to prevent it without haveing to edit them out every single time.
The punctuation is ambiguous, but I think you’re saying that you record everything via OBS, and that produces a .mp4 file which you import into Audacity for editing. Have I understood correctly?
I think I know what’s happening.
Digital audio data (“PCM” audio) is just a series of number. Each number represents the amplitude of the waveform at a specific point in time on a specific audio track. Normally these numbers are in the range -1 to +1. In special cases, sample value may be greater than 1, or less than -1, but they must always be numbers.
Inside the computer, numbers are represented as a sequence of “on” and “off” states. This is the computer’s binary representation, called “bits”. Some sequences of “bits” represent numbers, so represent characters, some sequences don’t represent anything.
When dealing with numeric values, there are three types of “special” values that can cause problems. “Infinity”, “negative infinity” and “NaN”. These values should never occur in valid audio because they are not “valid” numbers. I suspect that the imported .mp4 file contains occasional “corrupted” sample values that are not valid numbers, and that it is those invalid numbers that are producing the clicks.
To test this theory. Zoom in close on the start of the click and select a tiny bit of audio starting just before the click and ending just after the click. The selection should be less than 100 samples. Then use the “Sample Data Export” tool (http://manual.audacityteam.org/man/sample_data_export.html) to export the sample values to a text file. Set the “Measurement scale” to “linear”. Then open the exported text file and look carefully down the list of numbers. I’m expecting that at the start of the click there is an infinite, negative infinite, or NaN value.
I can confirm that this is an audacity issue. In the attached file i have Audacity and then another audio program. Only Audacity is showing the spike. As mentioned before you can’t hear the spike on the mp4 before i import it into audacity so it’s not something that is there by default.
Also another thing that just came to my attention on this fine Monday afternoon. My Setup during these issues was (-.- ( Desktop / Mic /Desktop )) anyway i sat down this afternoon after coming home from work and the computer was off (Therefore no sound whatsoever) any way i’m siting here doing nothing when i hear this clicking sound that after investigation appeared to be coming from the top left corner of my right desktop screen. I am not 100% sure if this is the issue i am experiencing but i will move my setup to .-- to get the mic away from both screens. (However i do live in Alaska so it is entirely possible my screen is poping due to expanding a contracting in the cold/warm temps we get on a normal day in the current season it can get as low as 25 on a night and a high as 78 during the day. The room my PC sits in is temperature controlled however only by an AC/heating unit as we lack central heating up here to keep the house a cousey all around temperature. ) I’ll do a test with my new setup to see if the poping presist in my audio and if not i will assume it was the clicking from the screen.
Thanks. I doubt that the popping in the recording are due to thermal effects as these pops are clear patterns of numeric data.
It could still be due to an effect of invalid data, but by the time it has been converted to WAV it has become “real” data. What I need to do now is to look at one of your mp4 files that does not pop until imported into Audacity.
Right now, everything is pointing at occasional bad data in the mp4 file. If Audacity is the only program that has problems with the MP4, then it could be a bug in Audacity.
What other players have you tried playing the MP4 with? I’m betting that it’s not just an Audacity issue.
It may be possible to workaround the problem by converting the MP4 to WAV with another program and then import the WAV into Audacity, but my guess is that any FFmpeg based converter will have the same problem.