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The video format conversion bit rate

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The video format conversion bit rate

video format conversion bit rate

Image quality, i.e. clarity, is a combination of several factors, in addition to bit rate and resolution, including frame rate.

video format conversion bit rate

Video formats basic knowledge quote: We tell you about MKV, MP4, H.265, bitrate, color depth, etc. – 4K Knowledge Encyclopedia – 4K China Forum – 4K123!

This tutorial is meant to cover some basic video and audio concepts and terminology. You can answer the following frequently asked questions in more detail:
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What is the difference between these MP4/MKV formats? Which image is better?
How is the video bitrate calculated? Why is it the same 1080p video, some big and some small?
In what format is the image information stored in the video? Is it the same red, green and blue as the monitor?
What exactly does 8bit/10bit mean? Why is it necessary to watch 10-bit video on an 8-bit monitor?
yuv420/444 What do these signs mean? Which is better?
What exactly do lines, planes, textures mean? Why does the video have high and low frequency?
The higher the bitrate, the better the video quality?
This tutorial will be described in detail in the following modules:
1. Encapsulation format (MP4/MKV…) vs media format (H.264/FLAC/AAC…)
2. Basic video parameters: resolution, frame rate and bit rate
3 Image rendering method: RGB model vs YUV model
4, color depth
5, medium chroma sampling
6, low frequency and high frequency in space: plane, texture and line
7, low frequency and high frequency over time: dynamic8
, clarity and brief description

image quality 1. Packet format (MP4/MKV…) vs. media format (H.264/FLAC/AAC…)
MP4+MKV is the most common type of video files you download. These files are actually similar to a package and their suffix is the packaging method of the package. These packages contain video (image only), audio (sound only), subtitles, etc. When the player is playing, please unpack the package first.(The professional term is called separation/division), take out the video, audio, etc., and then play it.

Since they’re just one package, that means the suffix doesn’t guarantee what’s inside or how much. Each element of the package, we call it a track, generally has the following:

Video (Video): In general, there should be, but there are exceptions, such as external audio track in mka format, in fact, there is no mkv video. Please note that when we talk about video, we do not include sound.
Audio (audio): Generally speaking, there should be, but in some cases it is muted, so there is no need to bring it.
Chapter: The segment information that came with the original Blu-ray disc. If the file is checked out, you can see the effect with the chapters in the player:
.potplayer right click screen, option-play-show marker/chapter marker in progress bar.mpc -hc
right click screen, option-setting-on Progress bar shows chapter mark subtitles
(Subtitles): Sometimes the file comes with subtitles, and the subtitles are not directly embedded in the hard subtitles of the video, so they are packed together in the packing container.
Others may have attachments etc which are not listed one by one. There is not necessarily a single track for each type, as MKVs with multiple audio tracks are often seen.

Each track has its own format. For example, it is often said that the video is H.264, the audio is AAC, these are the formats of each track.
Common video formats are H.264 (can be subdivided into 8bit/10bit), H.265 (currently also subdivided into 8bit/10bit), RealVideo (common in early rm/rmvb), VC- 1 (Microsoft-led, common in wmv). Basically H.264=AVC=AVC1, H.265=HEVC.
There are four common audio formats: FLAC/ALAC/TrueHD/DTS-HD MA, which are lossless, and AAC/MP3/AC3/DTS (Core), which are four lossy.

MKV vs MP4, the main differences are:

1. MKV supports encapsulation of FLAC as audio, while MP4 does not. But MP4 can also encapsulate lossless audio tracks (like ALAC, although it is generally believed that the efficiency of ALAC is not as good as FLAC)
2. MKV supports encapsulation of subtitles in ASS/SSA format, but MP4 does not. The subtitles produced by the general subtitle group are in ASS format, so internal subtitles are more common in the MKV format.
3. MP4 is an industry standard and its compatibility with video editing software and playback devices is generally better than MKV. That’s why vcb-s basically chooses the MP4 package for those videos that are optimized for mobile devices.
Beyond that, the two formats are largely interchangeable. For example, they all admit

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What is the bitrate of the mp4 video?

Mp4 Bitrate

The mp4 video bitrate is usually set to around 800.

mp4 bit rate

The basic algorithm is: bit rate (kbps) = file size (KB) * 8 / time (seconds), for example, D5 disk, the capacity is 4.3G, which takes into account the different audio formats, it is calculated as 600M, (so the remaining capacity is 4.3*1024-600=3803.2M), so the video file should be no more than 3.7G.

And if the capacity of the video file is 3.446G and the length of the video is 100 minutes (6000 seconds), the calculation result: the bit rate is approximately equal to 4818kbps (3.446*1024*1024*8/6000= 4817,857).

Bit Efficiency:

1. The bit rate in sound refers to the amount of binary data per unit time after converting the analog sound signal into a digital sound signal, which is an indicator to indirectly measure the audio quality. The principle of bitrate in video is the same as in sound, both refer to the amount of binary data per unit of time after the analog signal is converted to a digital signal.

2. In channel coding, a source data block of symbol size K is mapped to a codeword of symbol size N through coding, and K/N becomes the code rate, where assumes that the symbol table before and after encoding does not change.

The frame rate of 29.97 is the best.

usually:

1080*720 split resolution is about 5000K;

720*576 resolution is about 3500K;

640*480 resolution is about 1500K.

Extended information:

Some code rate principles:

1. Bitrate is proportional to quality, but file size is also proportional to bitrate.

2. If the bitrate exceeds a certain value, it has little effect on the image quality.

3. DVD capacity is limited, whether it is 4.3G standard, overdubbed or D9, there are limits. The information in the computer is represented by binary 0 and 1, and each 0 or 1 is called a bit, which is represented by a lowercase b, that is, bit (bit); uppercase B is byte, ie byte, one byte = Eight bits, ie 1B=8b; the capital K in front means 1024, that is, 1024 bits (Kb) or 1024 bytes (KB). Indicates the size of the file, usually using bytes (KB) to indicate the size of the file.

How does the bit rate affect the quality of the music?

How does the bit rate affect the quality of the music?

Does the bit rate affect the quality of the music?

There is a lot of talk these days that we have lost real music with the advent of compressed audio formats like MP3, AAC and the like. Is it really so? Will lossless music save music? Can an inexperienced listener tell the difference between MP3 and FLAC music? Let’s take a look at this problem.

What is Bitrate?

You’ve probably heard the term “bitrate” before and you probably have a basic idea of what it means, but it might be a good idea to familiarize yourself with its official definition so you know how it all works.

Bit rate is the number of bits or the amount of data that is processed over a period of time. In audio, this generally means kilobits per second. For example, the music you buy from iTunes is 256 kilobytes per second, which means that every second of the song contains 256 kilobytes of data.

The higher the bit rate of the track, the more space it will take up on your computer. Audio CDs typically take up quite a bit of space, so it has become common practice to compress these files so that you can burn more music to your hard drive (or iPod, Dropbox or whatever). This is where the “lossy” and “lossy” formats conflict.

Lossless and Lossy formats: what’s the difference?

When we say lossless, we mean that we haven’t really changed the original file. That is, we copy a track from the CD to our hard drive, but we do not compress it to the point of losing data. Essentially the same as the original CD track.

However, most of the time, you will probably extract your music in Lossy format. That is, you took a CD, copied it to your hard drive, and compressed the tracks so they don’t take up a lot of space. A typical MP3 or AAC album is probably about 100MB. The same album in a lossless format like FLAC or ALAC (aka Apple Lossless) will be around 300MB, so it has become common practice to use lossy formats for faster downloads and more hard drive savings. .

The problem is that when you compress a file to save space, you are removing chunks of data. Just like when you take a high quality image and compress it to JPEG, your computer grabs the raw data and “tricks” certain parts of the image into being basically the same, but with some loss of clarity and quality.

An example of how the JPEG graphics compression algorithm works
Remember that you are saving hard drive space by compressing music in lossy formats, which can make a big difference for an iPhone with 32GB of storage, but is only a trade-off in terms of size / quality.

There are different levels of compression: 128 Kbps, for example, takes up very little space, but it will also have a lower quality of playback than a larger 320 Kbps file, which in turn is of lower quality than the 1,411 reference file Kbps. From. 1,411 kbps is an audio CD level quality, which is more than sufficient in most cases.

The problem is not how much the music is compressed, but what equipment you listen to it on.

Does bit rate really matter?

As memory gets cheaper every year, listening to sound at a higher bit rate, or even lossless formats, is starting to become more and more popular. But is it worth the time, effort, and storage space on your phone or computer?

I don’t like answering questions this way, but sadly the answer is: it depends.

Part of the equation is the hardware you use. If you are using a good quality pair of headphones or speakers, you are used to wide frequency and dynamic range. As such, you are more likely to notice the downsides that come with compressing music into lower bitrate files. You may notice that low-quality MP3 files lack a certain level of detail; Subtle backing tracks may be harder to hear, the highs and lows won’t be as dynamic, or you may hear distortion in the lead vocal. In these cases, you may want a higher bit rate track.

However, if you’re listening to your music with a cheap pair of headphones on your iPod, you probably won’t notice the difference between a 128Kbps file and a 320Kbps file, let alone 1,411Kbps lossless music. Remember when you I showed the image a few paragraphs above and noticed that you probably had to look at it to see the flaws? Your headphones are like a truncated version of the image: they will make these imperfections difficult to perceive, as they are not physically capable of reproducing the music for you the way you want them to.

The other part of the equation is, of course, your own ears. It can be very difficult for some people to distinguish between two different bit rates for the simple reason: they listen to little music. Listening skills, like any other, develop with practice. If you listen to your favorite music often and a lot, your hearing becomes more accurate and begins to pick up small details and midtones. But until then, doesn’t it really matter what bitrate you use?

So what format and bit rate should you choose yourself? Is 320 Kbps enough for you or do you definitely need Lossless format?

The point is that it is difficult to hear the difference between a lossless file and a 320Kbps MP3 file. To hear the difference, you need serious high-quality equipment, good hearing, and some kind of music (for example, classical or jazz). .

For the vast majority of people, 320 Kbps is more than enough to listen to.

What else should you consider?

Music recorded in the Lossless format can be useful. Lossless files are more reliable in the future, in the sense that you can always compress them to Lossy format when you need to, but you can’t do the opposite and restore original CD quality from MP3 file. This, again, is one of the fundamental problems of online music stores: if you have created a huge music library on iTunes and one day you decide that you need more bitrate, you will have to buy it again, but this time only in CD format . …

Whenever I can, I always buy or copy music in Lossless format for backup.

I understand that audiophiles are like a needle under your nails. Like I said, it all depends on you, your audition and the equipment you have.

Compare two tracks recorded in Lossless and Lossy formats. Try a few different audio formats, listen to them for a while and see if it makes a difference for you or not.