When we record, there are always some inevitable small defects, such as noise, sonic boom and crackle. If conditions and environment permit, we will usually solve it on the spot by re-recording or re-recording. However, we are not so lucky to record the real sound. The scene is complicated and time is precious. Some small defects can only be made up by later means. Fortunately, in the digital age, these small flaws can be easily solved with iZotope RX4 software. This article will introduce how to use RX4 to reduce noise, repair sonic boom and clip. In the process of recording the video course "The Secret of Mixing", one of the microphones was specially used to record conversations, and these problems were also encountered. The author extracts a dialogue audio to explain, and the demo file can be downloaded separately (RX_LEAM.wav before repair and rx _ lean _ fix.wav after repair). You can compare the sound changes before and after the repair and try to repair it yourself. Listen to the audition file first, and analyze what needs to be repaired: First, this dialogue has obvious noise floor, which will affect the broadcast effect. Secondly, the gain setting of the power amplifier is unreasonable during recording, which leads to the level overload in many places, which is more obvious in 30 seconds and 34 seconds. Third, there is a sonic boom in 14 seconds. Let's solve them one by one.

First, reduce the background noise. Background noise directly affects the clarity of sound. If possible, try to reduce noise in the early stage rather than remedy it in the later stage. For songs and instrumental performances, noise reduction is not a necessary step, and slight equipment noise does not affect the mixing at all. For this regular background noise, you can use the "noise reduction" plug-in in RX4 to deal with it. "Noise reduction" is a great sampling noise reduction effect. Let's first understand the concept of "noise samples". Before the sampling noise reducer works, the plug-in needs to learn a short period of noise to let the plug-in know the characteristics of the environmental noise we want to reduce. The plug-in can identify the sound we need to process according to this noise sample, and when we choose the noise sample, we should try to choose "clean" and "representative" noise to obtain the ideal effect, generally, 1-2.

1, open the interface of "denoising" effector.

2, use the "selection tool" to select a short period of environmental noise from the material.

3. Click the Leam button to let the plug-in learn the noise samples.

4. Adjust the "threshold" and "decrease" parameters. The Threshold parameter is used to control the threshold of noise processing, the Reduction parameter is used to control how much noise is attenuated, and the Artifact Control parameter is used to adjust the proportion of artificial noise. Click the Preview button to listen to and adjust the parameters. After the parameters are adjusted, click "Process". The "noise reduction" effector also adds a certain artificial noise algorithm in the process of noise reduction, which makes the noise after noise reduction sound more natural. Our purpose is only to reduce noise, not to completely eliminate it. As for attenuation, you need to choose it yourself. The principle is to ensure that the noise is effectively reduced without obvious distortion. It is worth mentioning that the selection tool in RX4 is a combination concept. In addition to time selection (vertical bar selection), you can also select a part of the frequency (select a small piece), and even draw an area with your own mouse. Generally speaking, you can choose a vertical noise sample by using the conventional time selection tool, or you can try other methods yourself.

Second, repair clipping distortion Clipping distortion is usually caused by level overload, so before recording, it is necessary to plan the input level in advance, adjust the gain of the amplifier and leave a certain margin. Adding a hardware compressor can avoid clipping. If there is some slight editing distortion, we can still fix it through the "Decilp" plug-in in RX4 suite. By observing the waveform, it is not difficult to find that there are many places in the demo file that exceed 0dB, such as 30 seconds and 34 seconds, and the sound has been obviously distorted. We tried to fix it with the "Decilp" plug-in. Repair steps: 1. There are many clips in the presentation file. We can select all the clips 2, open the "Decilp" effector interface 3, click "Preview" to preview whether the distortion caused by the clips has been fixed, and click "Deal" to deal with it. The "threshold" parameter is used to determine the overload level that needs to be repaired, while the "compensation gain" parameter is used to limit the repair level. After the repair, the clipping distortion caused by level overload has been fixed, and now it sounds natural. Next, let's fix a crack in 14 seconds.

Thirdly, there are many reasons for repairing cracks. Sound card and system jam will cause sonic boom, and unstable AC power supply will also cause sonic boom. There are many reasons for cracks. After RX4, it's no big deal. Cracks can be easily repaired by using the "Spectral Repair" effector in RX4 suite. It should be noted that if you usually use RX4 as a plug-in, I suggest you choose a small area for processing and use destructive editing, because the place with sonic boom is very fixed, which will neither occupy resources nor cause new problems due to plug-in algorithm. Repair steps:

1, select the small clip to be repaired.

2, open the "spectrum repair" effector interface.

3. Without adjusting any parameters, click "Preview" to see if the sonic boom disappears.

4. If it has been solved, click "Deal" to deal with it.

5. If the sonic boom is not repaired, change the processing mode and preview again. After the sonic boom disappears, click to handle the sonic boom. The repair algorithm is different for different reasons. Using the default parameters, the crack is successfully and perfectly repaired, and several other treatment methods in the spectral repair plug-in will not be introduced one by one. Try it when dealing with practical problems. Judging by our ears, the aim is to successfully repair the sonic boom without creating new problems. So far, these three problems in the demo file have been successfully fixed. Compare the two demo files before and after the repair, and you will know how amazing RX4 is. It should be reminded that the problems that can be solved before and during recording should be solved as soon as possible, and the later repairs are only remedial measures. If you record a material full of crackling and noise, don't waste time repairing it, just throw it into the recycling bin!