Knowing the Bitrate mechanism and rules helps you optimally upload your videos to YouTube, based on the format. The same if you plan to make video contributions intended to be viewed on demand and downloaded locally by the user, as in the case of webinars meant for download.
Bitrate: Definition and Functioning
Bitrate is a term that indicates the amount of data relative to units of time. It is measured in Mbit per second and determines the speed of transferring data. This makes it essential to know the mechanisms useful for uploading videos and playing them in streaming.
Generally, the size of the bit rate is directly related to the quality of the videos and consequently to the file size.
Video resolution and bitrate
The bitrate and resolution represent two different elements. For resolution, it refers to the number of pixels within the frame. For example, two different cameras record the same video at a resolution of 1920 x 1080 but with specific bitrates based on the type of file chosen. The result will be two different files in quality and size.
In practice, the resolution is given by the number of pixels placed horizontally multiplied by the vertical ones. These constants are frequently indicated with usual abbreviations, i.e., SD, HD, 4K.
Low bitrate and high bitrate
A high bitrate will produce a higher quality video, but the size will also be higher. Alternatively, lower quality videos will be smaller or more compressed resulting in reduced quality.
This is a partially true axiom. File compression performed with codecs applies different algorithms from one program to another and from one device to another. And consequently, you can find higher quality images with lower dimensions thanks to the functionality of the codec used.
The amount of data to be stored implies a workload for the computer and the camera.
A GoPro comes with different bit rates compared to Sony full-frame mirrorless cameras despite both guaranteeing production in 4K but with a different final quality.
Relationship between bitrate value and video quality on YouTube
Several factors influence the quality of the video. They include:
- Type of codec chosen, the color processing,
- The size of the sensor
- The bitrate.
That can be 8-12 Mbps for HD video or 20 Mbps for 4K video. The quality of the frame also affects the quality and quantity of details, depth, and flexibility of color processing.
Factors that define the bitrate
In most cases, consumer cameras have a depth ranging from 8 to 12 Mbps. Many viewers can’t tell the difference in color depth even if an expert can pick up on this detail.
It is particularly evident in shots of the sky or dark background.
If you can mask the artifacts during the recording, they will surface when you intend to improve the saturation or the colors during grading.
Constant or variable bitrate. What is the best choice?
It is important to differentiate VBR from CBR. Distinguishing between a variable and a constant bitrate that differ in flexibility and adaptability helps optimize the entire stream of video production.
The VBR increases and decreases the value based on the image, requiring greater computing and coding capacity but managing to guarantee a better result. Encoding in several steps is always preferable.
The file size fits the image. The presence of motion or dark backgrounds increases the size markedly.
On the other hand, a constant bitrate encodes the entire video with the same value. This implies consistent quality, higher data usage, and slower loading on YouTube.
It is YouTube to recommend using 35/45 Mbps on video in 4K and 8 /10 Mbps of those in HD.
Type of video
You must choose the bitrate carefully for a YouTube video and consider the type of shot and the subject’s characteristics.
A video that does not contain movement, represented by a video interview, requires the same number of pixels for the entire scene. Consequently, it is also possible to opt for a low bitrate. The codec works at the level of the differences between the different images. On the contrary, it is necessary to increase the bitrate value with moving subjects.
Bitrate and audio files
The bitrate for audio files refers to the range of sounds available within a song or recording. 16-bit encodings support 96-decibel ranges. While at 24 bit, it reaches up to 144 decibels. The 16 bits represent a standard for most recordings, especially if they are for the web.
Just like with videos, you must seek an adequate compromise between the size and final quality of the reproduction.
There is a 50% difference in memory space used between 16 and 24 bits. Space that you can subtract from the encoding of the video file.
How to set the bitrate of your camera
It is advisable to set the bitrate even before starting shooting and keep it throughout editing and encoding. Avoid retouching it in editing. The input and output resolution should remain the same.
