Video file format extension/terminology

Source: Internet
Author: User
Tags ranges dvd decrypter

The full name of AAC is advanced audio coding, which will be a substitute for AC3 audio encoding. Based on Ac3, AAC has improved ac3. (However) The current player and hardware support for this coming audio format is still very limited.


Before a movie can be played, the player and the disc must establish a secure communication mode in which they can transmit real movie information to each other. Before establishing this method, on the other hand, they also need to ensure that there is a legitimate "audience"-this can be done through several key exchange, verification, and other methods.


AC3 (audio coding3 Audio Encoding 3) is synonymous with Dolby Digital. Dolby Digital is an advanced audio compression technology, it can encode a maximum of six channels with a bit rate of 448kbps. For more information, see the Dolby website.


The full name is advanced streaming format, which is a common format for streaming media of Microsoft and Real Media.


Audio and video are intertwined, and the most widely used video formats are used in PCs in windows. It illustrates how videos and audios are mutually attached without explicitly specifying the encoding/decoder.

Bup File

The Bup file is a backup of the IFO file. These files are usually stored on a DVD.

Cell (ID)

A cell is the smallest video unit on a DVD. it is usually used to store a chapter, a chapter, or a smaller unit, such as multi-view or branch plot information.

Codec Decoder
The encoding/decoder is a software program that is usually used to encode audio or video into a specific format. It can also be used to re-decode the media encoded in this specific format. Popular code/decoder: mpeg1, MPEG2, MPEG-4, Indeo and so on. Avi, ASF, and so on are only one format rather than encoding/decoder-they can be encoded using different codec.


Dar indicates the display aspect ratio, which represents the size of the screen. Most computer screens have a Aspect Ratio of, which means the horizontal size of the screen is 4/3 of the vertical size. For TV screens, there are many traditional 4-3 imaging methods, but now there are more and more imaging methods at. As we all know, the imaging method at presented a wider field of view than that at with the same diagonal length. The screen at is more suitable for Hollywood movies (image Aspect Ratio) which are usually. 35 or. 85 (meaning that the image horizontal size is 1.85 times the vertical size ).


The process of restoring the staggered video stream to progressive is called deinterlacing.

Demultiplexing anti-multiplexing
In contrast to multiplexing, in the process of anti-multiplexing, a merged audio/video stream is divided into several streams that constitute it (a video stream, at least one audio stream and one navigation stream ). Each vob encoder deserializes vob files before encoding (fast MPEG encoding, MPEG encoding to Avi, DVD encoding to mpg, and secondary MPEG2 encoding, at the same time, the DVD player does the same thing (audio and video will be processed in different processes of the personal computer, or decoded by different decoders ).

DVDs are usually encrypted by CSS (algorithm).-Imagine that you use 1 to represent. A sentence becomes a set of numbers. This is what we call encoding. Of course, CSS is much better (complicated) than this one, but it is not hard to crack. Decryption means the reverse encryption process, turning the number we get into a sentence, or re-playing our movie. You can try to copy a movie to your hard disk after your DVD drive is authorized and play it back. You will get a messy (inaccessible) image because it (data) still encrypted. General CSS Decryptors use a bunch of known decryption keys (such as decss or dodsrip-they contain a large number of keys but not all of them) or try to use algorithms to attack (crack) key (vobdec-why does it work for most discs because it does not depend on the disc ).

Digital Video
Digital Videos are generally compressed because the storage of an uncompressed movie occupies a considerable number of bytes-thousands of GB bytes (measured in numbers as the 10th power byte ). Because the General lossless compression is powerless for videos (storage), the video encoding/decoder has to remove unimportant information-something that is invisible to the human eye or unlikely to be seen. Because the modern compression algorithms using key frames are still insufficient, the key frames (keyframes), I frames and P frames (I and P frames) are used to save space.

God, do not confuse the obsolete DivX (Digital Video express digital video experience) system introduced by Circuit City '98. There are two different tastes of DivX: DivX is the name of the cracked Microsoft MPEG4 encoding/Decoder (Windows Media video V3. The codec was developed by Microsoft for its Windows Media architecture. It was initially used to decode AVI and asfformat, but all non-test versions were added with the AVI lock, so that they cannot be used for AVI encoding. Currently, only a few tools support the asfformat. What DivX creators do is remove the AVI lock, but they can be re-used for AVI encoding. The reason for replacing the name with DivX is to avoid confusion with many codec, in this way, Windows Media Encoder, which has both been cracked and not cracked, can be used on the same computer. The latest version of DivX also includes a cracked windows audio media encoding/decoder called DivX audio. Because its cracking is not perfect at present, using it for High-bit rate encoding will be limited. This codec is also called divx3.

Another DivX is the brand new MPEG-4 video encoding/decoder developed by divxnetworks. It provides more advanced encoding control and secondary encoding. Even better, he can play the earlier DivX;-) (divx3) movie. This codec is generally called divx4.

DivX basically removes all the additional features of the DVD: complimentary items, production groups, trailers, multilingual, Circuit City, and screen-filled introduction to a bunch of Hollywood greedy lawyers, allowing them to fully control the distribution of movies to end users and play movies at home. you can gain control. DivX is pay-as-you-go, and a DVD player that can play DivX must be connected to your telephone line, when you play DivX, the player will connect to the DivX central machine by phone for registration and pay by your credit card. The expenses for watching a movie are as follows: $4.50 for 48 hours for watching a movie; $2.50 for viewing outside. The DivX service was not authorized within one year (Warner, Sony, Shinkansen, and all other small production companies directly refused to authorize this format-thank you very much !!) And ended with negative comments from DVD sites on the Internet. Later, newspapers and TV News reported this seriously.

Because DivX uses triple DES encryption, it is not afraid of key attacks and is very secure. You cannot rip these discs unless you can crack them. In other words, your DivX disc will never become mainstream.


Dynamic range compression (dynamic range compression ). The AC3 audio track contains a larger range of Dynamic Ranges that can be processed by most audio devices. Therefore, most DVD players and DVD playback software will compress these ranges to some extent based on the actual dynamic range. In non-professional terms, the volume increases in a certain period of time. For example, the noise will not become relatively large but only slightly larger, but the general conversation volume will increase a lot. Because your player does the same thing, this is how to increase the volume.


An interlaced video stream contains a field rather than a frame ).


Fourcc is a four-character code that uniquely identifies the video data stream format. The video playback software queries the fourcc code and finds the video decoder associated with the fourcc code to play a specific video stream. For example: div3 = DivX low-motion, div4 = DivX fast-motion, DivX = divx4.

Formats used for DVD conversion format used for conversion
VCD: Video CD, which can be played on many DVD players and has corresponding playback software in almost every operating system. Playing this disk does not require a computer to be fast, but the image quality is similar to that of VHS. Its video is mpeg1 of 1150 kbit/s and the audio is mpeg1 audio Layer 2 of 224 kbit/s.
SVCD: Super video CD, used in Asian countries. The video uses MPEG2 to achieve the LD image quality, while providing high-quality surround sound. In addition, it can also leverage the advantages of the hardware decoder, many systems also have playing software. However, only a few low-end DVD players made in Asia can play SVCD. They are not sold in Europe and the United States. You can only watch them on your computer. The video uses MPEG2 with a maximum of 2600 kbit/s, and the audio uses mpeg1 audio Layer 2 with 224 kbit/s. Although MPEG2 multi-channel audio can also be used, it can only be encoded on Linux, and because of its little support for this format, it is hard to say that most players can play this 5.1-channel MPEG2 audio track. At the same time, menus can be provided for such disks.
Minidvd: a dvd stored on a CD with a maximum bit rate of 10 Mbit/s (including video and audio ). The video part uses MPEG2 and VBR. The audio part can be mpeg1 audio Layer 2, raw uncompressed PCM or ac3. If you are willing to accept the playback time limit, the video quality can be the same as that of a DVD. You can also create a menu like a DVD. The disadvantage is that minidvd can only be played on the PC. On affrey LD 2060, You need to upgrade the player to obtain the minidvd playing capability.
DivX/MPEG4: depending on the resolution and bit rate you choose, the video quality can be from lower than VHS to closer to the DVD. You can select multiple audio formats. You can make a DivX CD, which is very similar to a DVD, including multiple languages, subtitles, and menus. In addition, although no player can be used to play DivX, most operating systems can play DivX, including Mac, Linux, BEOs, and windows. However, there are also many strange problems, such as running properly on slow machines, and jumping on fast machines. But if he works on your machine, it is of course your best choice.
The basic unit of a movie. One frame represents an image. A movie usually plays 24 frames in one second, so it has 24 different images in one second. Suppose there are 24 BIRD images. In the first picture, the bird is on the left side of the picture, and then it gradually moves to the right. At the far right of the 24th-frame bird image. Assuming that the 24 images are played in order at a fast enough speed, the human eyes are like the bird flying from the left side of the screen to the right side.

I and P frames I frame and P Frame

The current frame only describes the difference between it and the previous frame (although the description is not accurate, it is not difficult to understand the meaning ). For example, we have a bird flying over a cloud-sky image. This is a key frame ). Then we can use the I frame to describe it as follows: Move the Bird 1 inch to the left and bottom.

IDCT & wavelet IDCT and Wavelet
The video information in the mpeg file is stored in the frequency domain rather than the spatial domain (that is, the image we see. Information is compressed in this way to reduce the amount of information transmitted in the channel. MPEG uses the discrete cosine transform DCT (discrete cosine transform) to transform the information in the spatial domain to the information in the frequency domain. When extracting spatial information from an MPEG stream, we need to use the inverse Discrete Cosine Transform (IDCT) to offset the discrete cosine transformation during encoding.

DCT and IDCT are actually Discrete Fourier Transform (DFT), but what we get through DFT is the plural, and the result of DCT/IDCT transformation is an integer. We can find more detailed information in university textbooks in DSP, communication systems, and other fields.
Wavelet is a basis space. Wavelet can have infinite types (such as Daubechies, Haar, Mexican hat, "spline", and zebra). However, wavelet is localized. Fourier functions span the entire space (from negative infinity to positive infinity), while wavelet is actually a pulse wave at different positions and scales.

The compressed data is divided into two parts. Generally, more than 90% of the data passes through the low-pass filter, while the high-pass filter filters out detailed data with very small values (of course, if the source of information is very nose, this is naturally not true ). For images, the greatest value of this method lies in the localization of the basis. Therefore, we can use wavelet to simulate non-consecutive parts such as the edge. After using wavelet, there will be no more strange JPEG halo.

Ifo File

Information files are usually stored in DVDs. These files contain information for the DVD player navigation. For more information, see the DVD Structure Article.

Interlaced Line Scan

Interlaced is a video storage mode. A Video Stream does not contain frames, but some fields, each field contains half of the rows in a frame (all are odd or all are even ). For more information about video storage mode and interlacing, see video basics.

Imagine that the combination of audio and video at a specific point is what we call staggered. The player recognizes the interleaved points to ensure that the audio and video are played in the whole movie according to the bonding points.

For more details, suppose we have 10 seconds of video and 10 seconds of audio clips. The video in every second is represented by V, and the audio is represented by a. If your staggered value is set to 10 seconds, the files on the disk will be in the form of vvvvvvvvaaaaaaaaaa. If the value is set to 1 second, the value is vavavavavavavava.

Inverse telecine
Telecine reverse engineering. In this process, the program source of 29.97fps is restored to the original 24fps.

A complete frame, but this frame is compressed as much as possible.


These two terms were used as extensions of MPEG-1 and MPEG-2 video data (just video, not including any audio ).


MPEG refers to the Motion Picture Expert Group, which is usually the source of the video format. This expert group explains the standards (or specifications) for digital videos, including mpeg1 standards (VCD), MPEG2 standards (for DVDs and SVCD), MPEG4 standards, and several audio standards including MP3 and AAC. Videos that use MPEG-1 or MPEG-2 standards typically use. mpg or. MpEG as extensions.

MPEG4 is a series of standards (or specifications) defined by the mpeg group ), it will become the next standard for digital videos (mainly used for video phones, streaming media on the Internet, and more ). MPEG4 allows multiple encoding methods. For example, a key frame can use ICT or wavelet to obtain different output quality.


MPG can be seen as an abbreviation of MPEG or as an extension of MPEG-1 and MPEG-2 video data.


Multiple MPEG 4: a combination of different bit rate encoding files. for example, you can combine 2000 kbit/s and 910 kbit/s encoded files with low bit rate, replace the image with 2000 kbit/s, which causes severe distortion. it can also be a combination of two types of DivX encoding: You can combine Low Motion and high motion files (different bit rates can also be used here ).

Multipass encoding multi-path Encoding

Before you read: The real multi-path encoding currently only exists in wm8 and MPEG-2 (scvd and minidvd. M4c is not a real multi-path code (read the m4c guide to find out what it is and how it works ). A multi-path encoding is used to analyze the video stream to be encoded in the first path and record everything it encounters. Suppose we have a small clip starting with a conversation scene, which has very few clips and the camera remains static. Then it becomes a Karate fight, which involves a lot of fast cutting and actions (people fly, kick, and punch in the sky ). In normal CBR encoding, the same bit rate is obtained every second (it is hard to say that 100% of CBR is maintained, but that is a branch) however, in the multi-path VBR mode, encoding uses the corresponding bit rate based on the video stream information. This means that the conversation gets enough bit rate and the fight gets higher bit rate. The more channels, the more detailed the bit rate allocation. In a single-path VBR, encoding must only determine the bit rate based on the knowledge of the previous encoding.

Multiplexing multiplexing
Generally, videos and audios are encoded separately. Then you must combine them to make them a playable movie (you can certainly play audio and video separately in two players, but synchronization will become quite difficult ). In multiplexing, audio and video tracks are merged into an audio/video stream. Audio and video streams appear to be intertwined, and navigation information is added to it, so that the player can maintain AV synchronization during fast forward/backward sampling.

Normalizing Standardization

Standardization includes finding the peak capacity of a sound track, and then adding the remaining parts of the sound track to the same level. This is usually done at the wav level, that is to say, all variables are integers, so they are not as accurate as DRC. Therefore, DRC is more popular in standardization.


OGM indicates Ogg media. It is an addition made by Tobias Waldvogel for Ogg container. ogm can be considered as another Avi container, it can contain Ogg Vorbis, MP3, AC3 audio, a variety of video formats, paragraph information and subtitles.


PGC indicates the program chain. It is a term that is often used in DVD writing. It is basically a playback item at the same time. For example, the main part of a movie has its own PGC. Every trailer on a DVD usually has its own PGC. The studio logo that appears when you play a disc has your own PGC and so on. The movie mode of smartripper and the IFO mode of the DVD decrypter will show you all the PFC on a DVD. For more information about PGC, see the mpucoder's DVD information site.

Progressive row-by-row Scan

It is opposite to interlaced. A video stream that only includes a full frame (frames) is considered to be a row-by-row scan. For details about Row-by-row/row-by-row scan, see video basics.

Quantizer quantization factor

To really understand this term, you must take a course on signal processing. In most people's terms, it represents a compression factor. The larger the value is, the more images are compressed. (therefore, high quantization factor means low image quality and low space occupation. Low quantization factor means high image quality and high space occupation ).
RFF/TFF mark

RFF indicates repeat first frame (Repeat first frame). This is a technology used to convert the source to a movie with 24 frames per second. It is called a technology that requires 29.97 frames per second. The RFF-encoded movie-tag tells the player to repeat one. TFF indicates that it is the top game and is used to implement telecine to create a 24 FPS movie as 29.97fps. You can get more information about film conversion to video in robshot's article about synchronization.

There is a lot of confusion in this regard. Basically, ripping indicates copying a DVD movie to your hard disk. This includes the authentication process of the DVD drive (when you try to copy the next file from the DVD, you will see a message: if your drive is not authenticated, this operation is not supported) and the real CSS decoding (Descrambling) process. CSS (contentated Scrambling System Data Interference System) is a anti-copy solution designed to prevent unauthorized copying of DVD movies, although many people argue that it is also designed to control where a DVD movie can be played, because there is no CSS license to play a DVD movie, you actually have to encrypt it with crack-I agree with this. Ripping is often used to describe the entire process of decoding a DVD (or even on this site), and then calls audio and video conversion another-less-format.


Smart bitrate control: smart bit rate control. A new DivX encoder called nandub can dynamically modify many internal parameters during the compression process, giving you better quality and more encoding control. For more information, see the SBC guide in the DivX guide.

Streamlist stream directory
The stream directory is an ASCII test file that includes the path name and your vob file name, one file per line. Here is a small example:

Save the file as streamlist.txt or streamlist. lst. Make sure that you save it as unformatted ASCII text. I suggest you use NotePad to edit your stream directory, because notepad will not save it as another format. Mpeg2avi requires that the stream directory extension be lst. However, when other programs use the stream directory, you can choose any extension. However, the GUI restricts the input file name/extension. If the stream directory does not appear in the file selection dialog box, you must rename your stream directory.

Convert the 24fps video source to 29.97fps or 29.97x2 staggered field/second. This article explains how this works.


Variable Bit Rate. It is possible to encode the audio and video in VBR mode, and the bit rate in the entire file will not be fixed (just as fixed in CBR ), the more complex parts of the video/audio will use a higher bit rate for better visual/auditory perception, while the other parts will get a smaller bit rate.


Variable key frame interval. The basic meaning is that the key frame is no longer inserted at a fixed interval as in the common DivX decoder. There are two ways to implement vki: the first method is to encoder uncompress the compressed frame and compare it with the original one. If the quality difference is higher than a set limit value, re-encode it. This encoding method is only applicable to a specific program: m4c. There is a command line-based version and a plug-in available for aviutl (the latter is described in detail in the aviutl wizard ). If you set the limit value too high, you will get a lot of key frames in the end. There is also a second method. It is mainly used to insert a key frame when the scene is changed. To achieve this purpose, the encoding program or decoder will detect a so-called "cut" (like the one used by the filmmakers) the first frame of a new scenario becomes a key frame. This can be achieved by using mpeg2aviar (part of avirevolution), m4c, or by installing the DivX vki decoder. If you use the latter, you don't have to worry about encoder. Every program that can perform DivX encoding can enable the file to have a key frame at the scene transform. When vki is reasonably used (only for the first method), it can help you increase or decrease the number of key frames to get higher quality again, especially when the bit rate is low, too many key frames will bring even worse quality.


Abbreviation of vki + mm4 + VBR MP3

Vob ID

Vob ID is used to group the cells in a PGC in a DVD.

Vob files
All DVD clips are stored in the vob file. A vob file usually contains a mix of Dolby Digital Audio and MPEG2 videos. The vob file is named as follows: vts_xx_y.vob. Here XX represents the title Y represents a part of the title. There can be a total of 99 titles and 10 parts. Although vts_xx_0.vob never includes any video, it is usually only menu or navigation information. There are two ways to find out which file contains the Movie Subject:

Method 1: Use a DVD player to play a movie, and then observe the single-host indicator or software player status window;
Method 2: the subject of a movie is the largest number in a digital continuous vob file. For example, vts_05_1.vob;
Vts_05_2.vob ...... Vts_05_8.vob (I have never seen a movie with nine files, but that doesn't mean it doesn't exist ).


VTS is short for the video title set. It is a collection of vob files and corresponding Ifo and bup files. For example, vts2 will contain vts_02_0.vob (including menu), vts_02_1.vob, vts_02_2. vob, vts_02_0.ifo, vts_02_0.bup, and other files. VTS is used to group video materials and their ancillary files. For example, a VTS is generally used for primary films (and sometimes includes trailers and logos of certain video companies), and other VTS is used for highlights.

Windows Media
Microsoft copyrighted PC audio and video systems. it is based on a series of encodings, which are used by windowsmedia player to play any supported format files. the latest Windows Media Player version is 7.0. windowsmedia 7.0 provides a series of new encodings, including an iso-compatible MPEG4 encoding (Windows video V1 ), an Improved MPEG-4 code named Ms video V7 (although I didn't find it any improvement over MS Windows video V3 Based on DivX ), this encoding supports deinterlacing and inverse telecine.


Extended CD is coming soon (can it be translated as the next generation? This is not suitable) CD format. This format allows you to use the second form of mode2 to burn your CD. This basically means that it contains fewer verification codes, you can store more data on a single CD. XCD allows you to store 700 mb of data in a normal mb cd. As I said, because there are only a few verification codes, XCD is not very reliable. Therefore, we recommend that you only put the data with additional verification (such as OGM) in the container into this CD. For more information, see the XCD guide.


Xvid is a text game. Read it in reverse mode and you will see a familiar word. Xvid is an open-source MPEG-4 decoder through which you can get better results than the best DivX decoder.

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