![\"Bit-depth\"](\"https:\/\/cat.com.mx\/wp-content\/uploads\/2018\/06\/372-C02-Shooting-secondary.png\")
<\/p>\n<\/p>\n
The “bit depth” in a video is “the amount of data allocated per pixel”.<\/p>\n
![\"BIT](\"https:\/\/d9pfvpeevxz0y.cloudfront.net\/blog\/wp-content\/uploads\/2019\/05\/bitdepthcameras.jpg\")
<\/p>\n
It has a different meaning than “bit depth” in audio.
\n“Bit depth” in audio…
\n\u2192 The amount of data allocated per sample
\n“Bit depth” on video …
\n\u2192 The amount of data allocated per pixel
\nReference \u2013 meaning and relationship of sample rate, bit depth, and bit rate<\/p>\n
further,<\/p>\n
bit depth
\ncolor depth
\npixel depth
\nThey all have the same meaning.<\/p>\n
For example, if the “bit depth” is “24 bits”, it means that 24 bits are assigned to a pixel.<\/p>\n
Also, “bit depth” is expressed in the unit of bpp (bits per pixel).<\/p>\n
Example: 24 bits per pixel = 24 bpp
\nFile size calculation
\n30fps image<\/p>\n
for example,<\/p>\n
Bit depth: 24bpp
\nResolution: 1920×1080
\nfor videos<\/p>\n
1920 pixels \u2715 1080 pixels \u2715 24 bits = 49766400 bits = 6220800 bytes \u2252 6.2 MB
\nYou can see that it will be a whopping 6.2MB per frame.
\n(For a 1 minute video at 30 fps, 6.2 MB\/frame \u2715 30 frames\/s \u2715 60 s \u2252 11 GB)<\/p>\n
By the way, this is the so-called “uncompressed video (RGB24)”.
\nDifferences due to color space.
\n450px-YUV_UV_plane.svg
\nQuote: YUV – Wikipedia<\/p>\n
Even if it says the same “24bpp”, the mapping method differs depending on the color space.<\/p>\n
for example,<\/p>\n
For “24bpp” in RGB:
\n\u2192 Assign 8 bits to each of R, G, B
\nFor YUV (YCbCr) of “24bpp”:
\n\u2192 Assign 8 bits to Y, U, V respectively
\nIt is so.<\/p>\n
In the case of YUV, the number of bits allocated depends on the “sample ratio”.<\/p>\n
The correct answer is to express YUV as YCbCr, but for some reason it’s commonly called YUV in the PC world, so I’ll call it YUV.
\nIn the case of YUV, it becomes “effective bit”
\nIn the case of YUV, the “sample ratio” differs depending on the format, so the method for taking the brightness and color difference will be different.<\/p>\n
for example,<\/p>\n
With “YUV444”, 8 bits each are taken from Y, U and V.
\nWith “YUV420”, Y takes 8 bits each, but U and V share 8 bits.
\nIt will be like this.<\/p>\n
So in the case of “YUV420”, you can see that the actual number of bits times one is “12 bits”.<\/p>\n
The “effective number of bits per pixel” at this time is called the “effective bit”. (“12bit” for “YUV420”)<\/p>\n
From this, there is a double difference in file size between “YUV444” and “YUV420”. . (It’s actually compressed with a codec, so it doesn’t make much of a difference)<\/p>\n","protected":false},"excerpt":{"rendered":"