I would like to clean up a 45 minute long mp3 that was unfortunately recorded at very high gain. Some sections are louder and worse than others. Most of it is severely clipped. It is a ‘meditation tape’ and the clipping induced clicks and thumps are very distracting. I think I understand how to even out the amplitude so that one playback volume setting is appropriate for the entire mp3. I have tried ‘Clip Fix’ under Effects and that simple fix does not seem to help.
I hope that someone experienced in the use of Audacity can tell me if patient work with ‘Repair’ will get rid of the loud clicks and bumps or if I should give up, transcribe the audio and record my own reading of it into a new mp3?
If a more detailed screenshot would help, please let me know.
We don’t need the image. We need the music file. Do you have an upload place you can post the stereo WAV file?
I wouldn’t count on a rescue, though. Clip Fix is an interesting arithmetic experiment not intended for use on extended, high quality music or heavy clipping. See: #2
The Four Horsemen of Audio Recording (reliable, time-tested ways to kill your show)
– 1. Echoes and room reverberation (Don’t record the show in your mom’s kitchen.)
– 2. Overload and Clipping (Sound that’s recorded too loud is permanently trashed.)
– 3. Compression Damage (Never do production in MP3.)
– 4. Background Sound (Don’t leave the TV on in the next room.)
It doesn’t look that bad at all… The red part is clipping. A “typical” MP3 ripped from a CD might be more than 50% “red”. I think you have some different issues.
Some clipping is normal in MP3s because of what the MP3 encoding does to the wafeform. But the slight clipping caused by MP3 compression isn’t audible. (If you hear compression artifacts, you are hearing something else.)
Clipping is difficult to fix in general (because it’s impossible to know the height & shape of the original unclipped waveform), and it’s especially difficult on MP3s because the MP3 encoding changes the wave shape.
Maybe you can upload the file somewhere so we can listen to it.
The truth is, it’s almost impossible to change a poor recording into a good recording… Sometimes you can make some improvement, but there are reasons that professional recordings are still made in soundproof studios with really goood equipment.
I much prefer Effect > Clip Fix to Effect > Repair for extended high quality recordings that are slightly clipped - much more “musical” in my opinion, not to say less labour-intensive until such time as Repair can be automated. I’ve fixed worse than that track above looks like with Clip Fix.
Thank you for the prompt replies and the reassurance.
I’ve tried more “looking and looking while listening” since I posted. I also hear a distinct difference in the distracting noises depending on the playback device. They are far more obvious played through speakers via our Sony DVP-SR500H than through Audacity on my computer and ‘Walkman’ headphones.
As I examine the file, it appears that it was created by pasting clips into a blank file. There are ‘transition noises’ as the waveform goes from ‘dead silence’ to recorded audio. There are obvious clicks, and sometimes there is obvious hum (thump) when the recorded audio is otherwise silent.
I’ll attach a 6 second clip in WAV format.
Here’s an image of the clip with a red arrow pointing to the hum and red circles near the clicks.
I have not chosen a place like ImageShack for audio sharing. Is there one that is preferred by the experts on this forum?
Perhaps I’m just being way too picky? Perhaps I could use other Effects tools to restrict the resulting waveform to frequencies representative of the speaker’s voice and diminish hum and with multiple passes to remove clicks? Perhaps I should further reduce the overall amplitude of the file. It does help to ‘balance’ the opening section with louder, later portions.
No, you’re not being too picky. Those transition bumps should not be there.
You can get problems like that if your two individual sounds do not “match,” but you don’t seem to fall into any of the usual suspects. You get the bumps in silent portions of the files.
Normally, that happens when one sound has DC on it…
I’m going with DC that you managed to filter by accident and disguised the problem. If you simply open both sound files in Audacity, do the middles both settle to zero up and down.
I’m afraid I don’t follow the terminology in this sentence:
" If you simply open both sound files in Audacity, do the middles both settle to zero up and down."
Do you refer to an Effect? I don’t see one with the name Settle.
I was playing with the 45 minut file. In places there seems to be what I hear as AC hum imposed on the signal. It is apparent when the speaking stops. When all sound stops, the abrupt transition from hum to silence is heard as a bump. You would probably anticipate this.
I selected some hum without any other signal imposed on it and tried applying the default Noise Removal settings to the entire file. I don’t think it had a significant impact.
I got rid of a lot of the very small looking clicks in otherwise silent parts by drag selecting them and applying Amplify at -20dB to them, driving the signal to 0 amplitude for all intents. I hope I didn’t generate more bumps.
Thanks for helping me understand the power of Audacity.
I got rid of a lot of the very small looking clicks in otherwise silent parts by drag selecting them and applying Amplify at -20dB to them, driving the signal to 0 amplitude for all intents. I hope I didn’t generate more bumps.
That’s what Control-L does, except it actually goes to zero.
The bottom one is the top one with drag-select and Control-L applied.
You do lose room tone when you do that, so if you have a pleasant natural low-level noises in your room while you’re performing, they will go to dead silence during that portion. It can sound a little strange.
If you’re obsessive enough, you can copy a little natural room tone and paste it in place of the straight-line silence.
Do you refer to an Effect? I don’t see one with the name Settle.
With nothing recorded (or just room tone), the middle of the blue waves should be zero as measured on the left-hand scale. With reference to this illustration, the waves on the left are defective. When they get done wiggling up and down, they don’t relax to zero, but some value lower than that. That will cause some serious sound damage when you’re editing.
Import both sound files. They will appear one above the other. When they’re silent, are both of the blue waves at zero?
