Audio Fundementals for video production
In the realm of video production, setting the right audio levels for different elements like dialogue, music, ambiance, and sound effects is crucial for creating a balanced and professional audio mix. The industry standards for these elements vary slightly depending on the platform or medium, but some general guidelines can be followed.
Dialogue Levels: Dialogue should typically hover around -18dB to -9dB. This range ensures that the spoken words are clear and easily intelligible without overpowering other audio elements in the mix.
Music Levels: When included in a mix, music should generally be set between -18dB and -22dB. If the music is used alongside dialogue, it could be lowered even more, to around -30dB to -35dB, to prevent it from overshadowing the spoken words.
Sound Effects Levels: Sound effects should be aimed between -10dB and -20dB. It's important to ensure that these effects are audible without causing distortion or overwhelming other audio elements.
Ambiance Levels: While specific guidelines for ambiance levels are less frequently mentioned, they should be adjusted to complement the scene without overpowering dialogue or crucial sound effects. Generally, ambiance should be subtle enough to add realism and depth to the scene without drawing attention away from the main audio focus.
Overall Mix Levels: For platforms like Netflix, the overall audio level should be within the range of -2dBFS to -20dBFS, allowing for dynamic expressions in movies and dramas. However, the recommended loudness value for TV broadcasting is -24 LKFS (Loudness, K-weighted, relative to Full Scale), with an acceptable range of ±1 dB of that value. For non-TV platforms like YouTube and Spotify, the standard seems to be generally around -14 LKFS.
These levels are guidelines and may need adjustment based on the specific requirements of the project or the platform where the video will be distributed. It's important to test the final mix on different playback systems to ensure consistent audio quality across various devices.
Understanding the different audio measurement terms
Understanding dB (decibel), LKFS (Loudness, K-weighted, relative to Full Scale), and dBFS (decibels relative to Full Scale) is crucial in the realm of audio production and mixing. Here's a breakdown of what each term means and how they relate to each other:
The decibel is a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.
In audio, dB is often used to express the loudness of a sound. A higher dB value typically indicates a louder sound.
LKFS (Loudness, K-weighted, relative to Full Scale):
LKFS is a standard for measuring audio loudness, developed to provide a more accurate representation of perceived loudness for human listeners.
The 'K-weighted' part refers to a specific type of filtering applied to the audio signal to mimic the frequency response of human hearing.
LKFS values are relative to the Full Scale (FS), which is the maximum level a digital audio system can handle without distortion or clipping.
LKFS is used in broadcast and other media to ensure consistent loudness levels across different programs and platforms.
dBFS (Decibels relative to Full Scale):
dBFS is a unit of measurement for amplitude levels in digital systems, which have a defined maximum peak level (the Full Scale).
0 dBFS is the maximum level, and all other levels are negative numbers. For example, -6 dBFS means 6 decibels below the maximum level.
dBFS is useful in digital audio because it defines a clear reference point (the maximum possible level) against which other levels can be measured.
Different mixes for different platforms
Creating a good mix for social media, broadcast TV, and film involves understanding and adhering to different audio standards and practices that are specific to each medium.
Platforms like YouTube and Vimeo have less regulated audio standards, but generally, it is recommended that the average loudness be around -14LKFS (Loudness, K-weighted, relative to Full Scale). This allows for content to be consistent with the platform's overall audio levels.
For social media, it's also important to consider the viewing environment, as many users watch videos on mobile devices. Therefore, ensuring that your mix is clear and balanced even at lower volume levels is crucial.
For broadcast television, there are specific standards established by laws and regulations, such as the CALM Act in the United States. The audio for broadcast TV is typically mixed to the BS 1770-3 a.k.a. A85 standards, which aim for a balanced mix that doesn't exceed the loudness limits set by these standards.
The general U.S. audio specifications for regulated content are -24LKFS Integrated Loudness and -2dBFS True Peak. Integrated Loudness measures the average loudness of the entire program, while True Peak evaluates the loudest moments of the audio.
Film mixing can be a bit more flexible compared to broadcast TV, allowing for a broader dynamic range to enhance the cinematic experience. However, when a film is prepared for TV broadcast or streaming, the mix needs to be adjusted to meet broadcast standards.
It's important to calibrate the control room to a standard that responds to the dynamic range of a mix similar to your target venue. Mixing sound for film often involves setting the listening volume in the control room to a level that corresponds with mid to small-sized rooms, which is typically around 79dB to 85dB.
When films are streamed or broadcast, the original mix might be altered by the platform's loudness and dynamic range controls, affecting how the mix is perceived by the audience. This underscores the importance of mastering sound mixes for specific delivery platforms.
Streaming Platforms (Netflix, HBO Max, etc.):
Streaming services like Netflix and HBO Max have their own set of audio specifications that content must adhere to. These standards ensure that the audio plays back consistently across different devices and environments.
For Netflix, as an example, the target loudness is specified at -27 LKFS (Loudness, K-weighted, relative to Full Scale), which is different from the -24 LKFS standard used for broadcast TV. This specification is part of Netflix's effort to provide a consistent and high-quality audio experience across all types of content and playback devices.
HBO Max and other streaming services likely have similar standards, though the exact specifications can vary. It's important for content creators to refer to the specific guidelines provided by each platform. These standards are generally focused on ensuring that the dialogue is clear and that the overall mix has a balanced dynamic range.
Integrated loudness and true peak measurements are critical for these platforms as well. The goal is to provide a comfortable listening experience for viewers, whether they are using home theater systems or portable devices.
In all cases, it's essential to use a good loudness meter during the mixing process to ensure that your audio meets the required standards and to achieve a mix that sounds good across various playback systems and environments. Each platform has its nuances, and being aware of these differences will help in producing an optimal audio experience for your audience.
Control Room Calibration:
Regardless of the platform, whether it's social media, broadcast TV, film, or streaming services, calibrating the control room is a crucial step. This ensures that the mix environment closely matches the audio playback environments of the target audience.
Calibration involves setting the listening volume to a standard level, often using pink noise and SPL (Sound Pressure Level) meters, to create an accurate mixing environment. This process helps in making critical decisions about the balance and dynamic range of the mix.
Loudness Normalization and Playback Control:
Many streaming platforms employ loudness normalization and dynamic range controls to ensure consistent volume levels across different programs and advertisements. This means that the original mix might be processed differently on these platforms, potentially altering how it's perceived by the audience.
Understanding and preparing for these variables is key to ensuring that the audio plays back as intended on different platforms.