![\"Audio](\"https:\/\/mobilebeat.com\/wp-content\/uploads\/2017\/05\/Screen-Shot-2017-05-05-at-3.55.57-PM.png\")
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The bit rate in a video is “how much information is packed in one second”.<\/p>\n
![\"BIT](\"https:\/\/i.stack.imgur.com\/m4xb7.png\")
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What if the bit rate is high?
\nBasically, the higher the bit rate, the better the picture and sound quality.<\/p>\n
* Although it is closely related to the “codec” described later, it will basically improve.<\/p>\n
There are two types of bit rates
\nBit rates are assigned separately for “video” and “audio”.<\/p>\n
The higher the bit rate assigned to “video”, the better the “image quality”.
\nThe higher the bit rate assigned to “voice”, the better the “sound quality”.
\nAlso, the sum of the two bit rates is “is called the oval bit rate (total bit rate)”. (This oval bit rate is called “video bit rate”)<\/p>\n
\u25b2 If you open the video file properties and open the “Details” tab, you can see “What is the bit rate?”<\/p>\n
(However, this Windows function is unreliable, so it is better to use video analysis software like MediaInfo)<\/p>\n
soon,<\/p>\n
Oval bit rate = video bit rate + audio bit rate
\nIt becomes the calculation formula.<\/p>\n
So even if it says “bit rate is high!”, It may mean “video bit rate is high” and “audio bit rate is not high”.<\/p>\n
In other words, in such a case, the video will be “Image quality is good, but sound quality is not good …”.<\/p>\n
Basically, the file size of “audio” is much smaller than that of “video”, so even if you increase the bitrate of “audio” significantly, the overall size of the file will not change as much.<\/p>\n
Therefore, “speech” is often encoded uncompressed (linear PCM).<\/p>\n
Relationship to image quality
\nThe higher the “video” bit rate, the more accurate the color information that can be assigned to all pixels.<\/p>\n
as a result<\/p>\n
High bit rates improve image quality and
\nIf the bit rate is low, the image quality will deteriorate.<\/p>\n
\u25b2 High bit rate (12 Mbps, 2.57 MB) \u25b2 Low bit rate (90 kbps, 20 KB)
\n* Actually, it is a gif video, so the bitrate is not accurate.<\/p>\n
Bit rate difference<\/p>\n
Also, in the case of a low bitrate, if you allocate bits evenly to all pixels, you will run out of bits, so in scenes where similar colors are continuous (such as a scene where the blue sky stretches without end), etc. Try to reduce the bits preferably.<\/p>\n
As a result, “block noise” \u2193 is likely to occur in such scenes.<\/p>\n
Block noise
\n\u25b2 Example of block noise (block noise)<\/p>\n
Relationship to sound quality
\nThe audio bit rate is<\/p>\n
Sampling rate (Hz) x bit depth (bit) = bit rate (bps)
\nIt can be expressed by the formula.<\/p>\n
For example, when recording sound as digital data<\/p>\n
How often do you record (= sample rate)
\nHow much data is stored per interval (= bit depth)
\nDecide and register.<\/p>\n
for instance,<\/p>\n
Sampling frequency: 44000 Hz
\nBit depth: 24 bit
\nIf so, the sound is divided and recorded 44,000 times per second, and the sound is recorded using 24 bits for every 44,000 times.<\/p>\n
In other words, if you want to improve the sound quality, you can increase the “sample rate” or “bit depth”.<\/p>\n
Increase the sample rate \u2192 Soft sound
\nIncrease the bit depth \u2192 Increase the expressiveness of the sound, such as finesse and volume
\nReference: Meaning and Relationship of Sample Rate, Bit Depth, and Bit Rate<\/p>\n
Relationship to codec
\nI mentioned earlier that “the higher the bit rate, the better the image quality and sound quality”, but the image quality and sound quality are “codecs”. they are closely related to the “.<\/p>\n
A “codec” is something like a “compression algorithm” for compressing “video” and “audio”.<\/p>\n
Reference: What is video format? Codec difference<\/p>\n
for example, “the H.264 video codec” It is a very famous codec that is also used on Youtube and Nico Nico Douga,<\/p>\n
(Addendum: Not used now …)<\/p>\n
“H.265” which improved the “image quality by file size” from “H.264” There is a codec called “which.<\/p>\n
“H.265” is “H.264 at about half the bit rate of”, “H.264 will get the equivalent of image quality and”. (The compression rate is double)<\/p>\n
for instance,<\/p>\n
Using “2Mbps” video bit rate with “H.264 codec”
\nVideo using “2Mbps” bit rate with “H.265” codec
\nIf there are two videos, the image quality of “H.265” is twice as beautiful even though the bit rate (file size) is the same.<\/p>\n","protected":false},"excerpt":{"rendered":"