Video / Audio Standards -Codec / Container Part 3

Container type / characteristics

avi Audio and video interleaving. An old container that is a Windows standard. Although it is widely used, it is rarely used on video sharing sites because it is incompatible with browsers. Most of the editing programs support this AVI format, making it very easy to edit. It’s a good idea to use this as a reference when editing. In addition, there is a large amount of data that can be stored. Video part: “MPEG-1 / -2” “H.263” “H.264” etc.
Audio part: “Linear PCM” “MP3” “AAC” etc.
mov This is a Macintosh standard. It can be played with QuickTime, etc. It works well with browsers and can store a wider range of data than AVI. If you’re on a Mac, it’s the basic container for editing and playback. Video part: “H.263” “H.264” “Pixlet”, etc.
Audio part: “MP3” “AAC” “Apple Lossless”, etc.
wmv Official name “Windows Media Video”. It is a Windows standard. It goes well with web pages. However, since the data format that can be stored is smaller than that of avi, there are few users. Not suitable for editing. Since it supports Digital Rights Management (DRM), it is mainly used for general business and organization video distribution. Video part: “H.264”, etc.
Audio part: “WMA”, etc.
mpg Synonym for mpeg. Compared with avi, etc., the video data that can be stored is very small, only “MPEG2” and “MPEG1”. This format is often distributed as video content on the Internet. Video part: “MPEG-1 / -2” only
Audio part: “MPEG2” “AC3” “LPCM” “DTS” etc.
wav A container format for speech data developed by Microsoft and IBM. It is also described as “WAVE”. Reading is “wave” and “web”. It is commonly referred to as a “wave” to avoid confusion with the Web. Typically often used for uncompressed and linear PCM sampling, it can also contain compressed audio data such as “MP3” and “WMA”. Video part: None
Audio part: “MP3” “WMA” “LPCM” etc.
mp4 There is a codec with a similar name, but this is a container. It is often used for video sharing sites, such as YouTube, that claim to have “high image quality.” In many cases, the voice is distributed as a single unit and in this case it is used for the ringtones of mobile phones. Video part: “H.263” “H.264” etc.
Audio part: “MP3” “AC3” “AAC” etc.
flv It is a video container in flash format that is often used on YouTube. The main content is “H.263 / H.264”. It is widely used in video sharing sites because it is very compatible with web pages. The official name is “Flash Video” Video part: “H.263” “H.264” etc.
Audio part: “MP3” “PCM” “ADPCM” “AAC” etc.
3gp This is a video file recorded by 3GPP. It is used in the “i-motion” function of the “FOMA” mobile phone service provided by NTT DoCoMo. If you want to play the video on a doCoMo mobile phone, save it in this format. (Except for smartphones) Video part: “H.263” “H.264”, etc.
Audio part: “AAC” “AMR”, etc.
3g2 This is a video file recorded by 3GPP2. It is based on MP4 format. It is used in the “EZ movie” function of KDDI’s “au” mobile phone service. If you want to play the video on your au mobile phone, please save it in this format. (Except for smartphones) Video part: “H.263” “H.264”, etc.
Audio part: “AAC” “AMR”, etc.
Term supplement
Some new terms have emerged which will be briefly explained here. I would like to write more details in another article.

fire
A still image. The video is made to appear as if it is moving by displaying a series of still images at high speed. 30 frames per second means that 30 still images are displayed per second. The unit is “fps” (the frame rate is said to be 30 fps, etc.). If this value is high, the video will move smoothly. (Frames per second)

Compression rate
It is often used as an index of how much the file size is suppressed.

Bit rate
This is an expression that represents the amount of data (number of bits) that can be sent and received per second. The unit is bits per second (bps). If this value is large, it will increase the amount of data that can be sent and received per second and improve the quality of music and videos.

Video / Audio Standards -Codec / Container Part 2

Codec types / characteristics
film

The following codecs have little or no deterioration in image quality. When used for video editing, deterioration of image quality due to encoding is minimized. Also, the load is low both during compression and playback, and we are good at reverse playback. Instead, the amount of data tends to be large.

Motion JPEG Reads as Motion JPEG [Motion Jepeg: MJPEG]. As the name suggests, it is a JPEG compression of each frame of the video. Since JPEG compression deteriorates the image quality to some extent, since there is no compression between frames, the playback and compression load is small, and it is easy to delete frames one by one. It is often used in the recording part of digital cameras.
Lossless compression codec When compressed in this format, there is no deterioration of the video except for the color space. The famous ones are Huffyuv and Lagarith Lossless Video Codec. It is recommended to use it as an intermediate format when you do not want to deteriorate the image quality but want to reduce the capacity, or when editing a video.
The following codecs are formats intended to save and distribute edited and created videos. The data capacity is very small, but it is degraded compared to the original video. Also, because it uses a complicated compression algorithm, it is not suitable for editing work such as joining videos, cutting and inserting. Basically the playback load is high.

H.263 A video format developed for low bit rates. Often used for videophones. If you use DivX, Xivd, etc., it will be in this format. There are many users because the playback load is low compared to other codecs. However, the capacity is a bit large.
H.264 It is a very popular video format today. It is widely used in terrestrial digital broadcasting, mobile phones, next-generation DVD, etc. It is an excellent codec with a high compression rate and little deterioration in image quality. Good for playing low to medium bit rate videos. Instead, the playback load is quite high, so some machine power is required to reproduce it. Encoding a high-capacity video is likely to cause dropped frames. Sometimes called “MPEG-4”.
MPEG-1 Read as MPEG-1 [Mpegwan]. Created by an organization called Moving Picture Experts Group (MPEG). It is used for video CDs. It was a format that was thought to be able to play VHS quality video on CD, but now that VHS has become obsolete and DVDs and BDs have gone mainstream, it has to be said that there is less need to compress in this format. The playback load is low, but the capacity is high.
MPEG-2 This is the mainstream MPEG videos. Since it is good for playing at medium to high bit rates, it is used on DVDs and digital terrestrial broadcasts that require high picture quality. Since it is a lossy compression, the compression rate is high and the data capacity can be reduced. Since the data transfer rate requires 4 to 15 Mbps for both video and audio during playback, it is not suitable for low bit rate video.
Audio
PCM is an uncompressed audio codec that has been around for a long time. It is one of the methods for converting analog data into digital data, which is called pulse code modulation [PCM]. It can be played on most computers. The sound quality is very high, but the capacity is also great. Most of them are in WAV containers by themselves.
LPCM Read as linear PCM. One of the PCM methods, also uncompressed audio. Since there is no lossy compression, this is also very high quality sound. However, the capacity is also large. It is widely used in the audio part of DVD and BD, games for PlayStation 3, etc.
MP2 MPEG audio codec. The extension is “.mp2” or “.mpc”. It is often used as a set with MPEG1 and MPEG2 videos. Some DVDs are recorded in this format. The compression ratio is neither high nor low.
MP3 is an audio codec that has been exploding since 1998. You may have heard of it. The extremely high compression ratio can reduce the amount of data. Also, since compression is done using human auditory psychology, there is little deterioration in sound quality despite the high compression rate. Due to its excellent format, most devices and software support playback. By the way, the official name is “MPEG Audio Layer-3”.
AAC AAC [Advanced Audio Coding] is a standardized format that aims to achieve high sound quality.

Video / audio standards -Codec / Container-

In the past, when it came to video, televisions and camcorders, and audio (music), cassette tapes and CDs didn’t require many standards.

However, now that the Internet has become mainstream, videos have also appeared that can be embedded in web pages. In addition, small portable terminals such as iPod, Walkman and PSP support music and video playback, so it is necessary to have adequate video and audio standards for each one.

As a result, there are now many video and audio standards. Since each has its own characteristics, some devices (software) can be played and some devices (software) cannot. For example, the video format that can be played on the PSP is the MP4 format, and the audio on the iPod and the Walkman is in MP3 format and WMA format.

And it can’t open files other than the supported formats.

Many people want to carry video and audio on their mobile terminals, but as mentioned above, there are various content formats, and the formats supported by the device (software) are different. It is easy for the phenomenon of “I want to play with, but I can’t, I’m in trouble” to occur.

To avoid this, please understand what file format there is in the world along with its characteristics and “convert (encode)” the file to a format that supports playback, or use software that supports playback. You will need to prepare it.

In this article, I will first focus on “containers and codecs”, which are the concepts necessary for proper playback and conversion, and “video / audio formats and characteristics”.

* Since the explanation is quite approximate, the content may be incorrect or too simple to be misleading, so if you want more information, check the specialized site.

Encode decode

Encode has the meaning of “encode”. If you handle the video and audio data as it is, it will be a large amount of data, so the computer will do a lot of calculations, encode it, and reduce the storage capacity. This work is called coding. So the word “compression” is also used.

Decode has the opposite meaning of “decoding”, “decompression” and “playback”. Encoded video and audio can be played back by decoding with a compression / decompression program called “Codec” for each encoding method.

Since playback is the main job, the words “unzip” and “unzip” that are used for archives such as zip are not used.

Container codec
Before we start talking about audio and video standards, let’s talk about “containers” and “codecs”.

Codec
Codec [Codec] refers to devices / software and algorithms that can encode (encode) and decode (decode). As I wrote earlier, it is an item related to video and audio compression / decompression.

Compression and playback methods differ by codec type, and data capacity and playback load also differ, so there are appropriate playback environments for each.

container
To be precise, it is called a “container format”.

A container is a type of file format that defines how audio and video data is stored. Simply put, it is a “box” that contains audio and video data. There are different types of containers (boxes) and the data formats that can be stored in each one are different.

If you want to store the video and audio together, you will need to store the data in this container. Since there are restrictions on the data formats (differences depending on the codec) that can be saved in the container, it is necessary to encode them carefully.

What is the difference between avi and mp4?

There are various video file formats, but do you know the difference between “AVI” and “MP4” file formats?

“AVI (extension: .avi)” is an abbreviation for “Audio Video Interleave”. It is a standard video file format for Windows developed before 1992 and can use various codecs such as Xvid, Divx, MPEG-4, and H.264. “MP4 (extension: .mp4, .mv4)” is a standard developed based on MOV and standardized in 2001, and it is a container file that stores audio and video as MPEG-4. Comparing AVI and MP4, MP4 has better image quality and smaller file size Basically, there is nowhere that AVI is superior when comparing an AVI format file with an MP4 format file. Since MP4 is a later standard, it is only natural that MP4 is technically superior.

If you have a video file in avi format, you can reduce the file size by converting it to mp4 format. It is possible to convert without deterioration, so if you are interested, please see the article linked below.

How to convert flv / avi / wmv videos to mp4! [No deterioration / easy]
There are various types of video files, such as flv, avi / wmv, etc., as well as mp4, but some programs do not support them and they may not be usable and need to be converted. This time, I will show you how to convert video formats like flv and avi / wmv to mp4.

Thumb

What is the difference between avi, mp4 and H.264?

I explained the difference between AVI and MP4 above, but I think some people may be interested in “H.264”. H.264 (MPEG-4 AVC) is one of the video compression standards and was recommended in 2003. It has more than twice the compression efficiency of MPEG-2 and was a format that was often used when uploading videos to sites. of internet videos circa 2010s.

The difference between AVI, MP4 and H.264 is that H.264 is one of the video codecs in MP4 as explained above. So it is officially one of the standards used in MP4, so keep in mind that it is completely different from AVI and it is one of the MP4 video codecs. Although it is a difference in performance, it is okay to acknowledge that AVI is the worst. The image quality of videos encoded with MP4 (H.264) is better than that of MP4, which does not specify the encoding method. H.264 is now an inferior technology to the latest video compression codecs, but many users still use it