In the first and second issues of the audio topic, the characteristics of the microphone and the choice of different scenarios are introduced, everyone has a basic understanding of recording, and also knows how to choose a microphone, so in this issue we will talk about the recording process and some tips.
In video shooting, we often draw the sub-shots according to the script first, specific to the scene of each picture, there are detailed annotations, but we ignore the equally important recording script.
In fact, in the rigorous creation, in addition to the sub-shot of the picture, it is also necessary to prepare a set of recording schemes to ensure that the video and audio links do not fall off the chain when shooting.
When preparing the recording plan, it is necessary to explore the shooting environment in advance, understand the noise base of the pickup environment, and the noise generated around it, the noise here includes the noise floor and the sound that is not beneficial to the picture, for example, in the airport terminal, the sound of the broadcast may have a certain impact on the dialogue of the characters, but it is not all noise, which can increase the sense of presence after clever use; if it is filmed indoors, it must be pre-recorded to understand the degree of reverberation of the sound.
Reverberation is an acoustic characteristic, the sound in the environment encounters obstacles to produce reflections, each obstacle will absorb a part of the sound energy, when the sound source stops sounding, the sound wave in the room to go through multiple reflections and absorption, and finally disappear, we feel that the sound source stops sounding after there are several sound wave mixing for a period of time; appropriate reverberation can increase a certain sense of the environment, such as shooting scenes in the auditorium, etc., but excessive reverberation is easy to affect the character dialogue, blur the language, but there will be an inferior visual experience.
When the reverberation affects the dialogue, it is necessary to make notes in the recording scheme, you can use two solutions, one is the post-ADR re-recording, but the cost is higher, unless it is a professional voice actor and a professional sound recordist, it is difficult to restore the sound phase of the scene; the second is to appropriately transform the environment, increase the sound absorption device, so that the reflection of the sound wave is reduced as much as possible, the scene method is to lay carpet on the ground, and place the sound-absorbing sponge (egg cotton) in the surrounding environment, which can achieve a better recording effect.
Maple Flute's SR-RF5M mobile studio windshield is also such a principle, through high-density sound-absorbing sponge, to create a small range of local low reverberation environment, low cost to create a high-quality recording studio.
In addition to understanding the ambient noise and reverberation in advance, the sound recordist also needs to familiarize himself with the script in advance and choose different microphones in different scenes, which we have introduced in detail in the second issue and will not be expanded here.
The recording scheme is as important as the shooting scheme, which needs to be synchronized with the sub-shots, ensuring that each shot has a recorded note in order to achieve the essence of film and television sound - to add color to the picture.
Simple recording scheme format for reference only
After developing the recording plan, let's talk about some tips on recording.
001 Close to the sound source
War photographer Robert Kappa said, "If you don't shoot well enough, it's because you're not close enough." This phrase can also be applied in the audio field: "If you don't record clearly enough, it's because you're not close enough."
When the larger the sound source picked up, the noise that does not want to be picked up is naturally smaller, but it is not endlessly close, you can achieve better audio recording, you need to consider the best pickup distance of each microphone according to the sensitivity of the audio and the signal-to-noise ratio, such as the best pickup effect of the on-site microphone in the range of 20-40 cm, beyond this range, the ambient noise will increase, the sound source is not clear; and below this range, it is easy to produce a close-talk effect (also known as the near-field effect), and the low frequency of the sound source is more obvious, If there is no intervention of the low-frequency filter, the sound will be distorted; but the close-talk effect is not without benefits, in some specific scenarios, the use of the low-frequency specific gravity increase characteristics, can create a warm, full and thick sound.
The Maple Flute SoundBird V1 can turn on a low cut at 200Hz to achieve noise reduction and suppression of the close-talk effect.
002 Correct level
Too close to the sound source sometimes produces a negative effect, that is, pop, such a sound can not be repaired, can only be re-recorded, so how to avoid the impact of sound overburding? Getting the right levels is paramount.
In the recording of audio, there will be two ways to judge the loudness of the sound, the first method is subjective, using the method of real-time monitoring to judge, in the outdoor general use of monitoring headphones for monitoring, but there are more interference factors, but also related to the amplifier of the monitoring interface, and can not correctly judge whether the loudness is appropriate.
Professional monitor speakers
The second is judged by the audio histogram, now the camera or camera's audio histogram, there will be green, yellow, red three color blocks to display, when the loudness of the sound in the yellow area, it means close to the overburden, so as far as possible to let the sound in the green and yellow range; if it is a professional tape recorder, its audio histogram is generally digitally marked, then to ensure that the audio is in the range of -9 to -12db, in order to record the correct level.
Monitoring headphones are close to the human ear, can not get a unified monitoring volume, and monitoring audio can be unified monitoring volume, the monitoring sound for panning adjustment and position placement, play a period of pink noise, when the loudness reaches about 70db, you can use as a reference monitoring level, but the audio histogram is still essential.
Tips: Are volume, level, and loudness the same concept? Volume refers to the size of a sound from a life point of view, and the level is used in the process of electroacoustic development to the audio field, the units it uses, dBV, dBu, etc. are volume units; and finally loudness is a synonym related to frequency. In daily communication, the description of the size of the electroacoustic sound is generally more rigorous; when subjective feelings are involved, the "loudness" can be used to describe the sound size; in the absence of a special context, the "volume" is a panacea.
003 Audio Security
Getting the correct level is actually part of the audio security, many times "recorded" is more important than "recorded well"; in addition to the correct level, there are two ways to ensure audio security:
The first is independent recording, now the camera and camera generally have an audio input interface, but the drawbacks of camera recording are also obvious, the audio format it records is relatively single, the post-adjustment space is not large, the richness of details is not as good as the recorder, so independent audio recording is essential, the recorder has the level adjustment, filter, and phantom power supply and other functions are very professional, can eliminate the more complex processing process in the later stage.
Maple Flute SR-VRM1 voice recorder, can independently complete the recording of audio, XLR's professional balance interface as far as possible to maintain the authenticity of the sound, and can provide 48V phantom power, up to 48kHz 24bit multi-channel BWF file format.
The second is multi-track recording, in a complex environment, it is difficult to ensure that the sound emitted by the sound source is at the same level, if it is suddenly amplified volume, the recorded audio is too late to adjust, and it is easy to appear pop phenomenon, then you can choose multi-track audio recording, that is, recording with a safety track.
Generally, the audio we record is two-channel, and the safe audio track recording is to adjust the pickup level of the secondary track to -6dB of the main audio track, so that even if the main audio track has a pop, the secondary track can still save the sound, copy the safety audio track in the later stage, cover the irreparable main track, and realize the restoration of the sound.
Whether it's shooting or recording, we advocate bringing post-production thinking into the pre-work, which can provide efficiency as much as possible, speed up the shooting schedule, and reduce the pressure on post-production.
In terms of recording, although the later stage can also achieve de-reverb, noise reduction and other functions, but will always have a certain impact on the original sound source, or compression, or pitch change; so in the early recording as far as possible to record the sound more purely, so as not to produce a sense of stripping from the picture.
AU software comes with adjustable effects
For example, when shooting, the camera and microphone have level adjustment functions, so how do you need to operate? The answer is very simple, you need to have a post-front thinking, the camera level is opened small, and the microphone level is large, to obtain an intermediate value, so that you can maximize the sensitivity of the microphone and the signal-to-noise ratio, because the adjustment of the camera level is essentially a post-algorithm processing, if the camera level is increased, the microphone level is reduced, which means that the camera level amplifies the sound source at the same time, it will also amplify the noise, which is not desirable for film and television recording.
For video shooters, if you want to do a good job, you must first use it, but also know its device, understand the performance and use of the microphone, in order to better add color to the picture.
On the audio recording topic, we have made a preliminary introduction to you through these three issues, from the development of recording history to the use of equipment, and finally to the actual operation, hoping to bring you some inspiration, but film and television recording is a very wide range of fields, not this more than 10,000 words can explain clearly, if you are interested in this aspect, welcome to discuss and communicate together, common progress.