Video & Audio Codec
Video Codec: video codec is a way to convert raw (uncompressed) digital video to a compressed format or vice versa by way of compression or decompression.
Video compression, also call video file encoding, is conducted to reduce the size of the original video file by removing the less important part including image and sound from the original file, thus taking less space for the purpose of easy and smooth transit over the internet.
Video decompression, also known as video file decoding, is a reverse process of video compression, through which the compressed video file returns to its original size.
Commonly used video codecs: H.264, H.265, MPEG4, MPEG-2, MPEG-1, Xvid, DivX
Audio Codec: audio codec is a way to switch one audio format to another by means of compression and decompression.
Technically, sound consists of different dynamic range, so audio compression is carried out to produce the sound within our range by replacing one audio format with another, in an attempt to strike a balance between the soft and loud parts of soundtrack, thus reducing the size of the audio file for more space and smooth transit. Audio decompression is the reverse process of audio compression.
Commonly used audio codecs: PCM, MP3, FLAC, OGG, AAC, WMA
Frame rate, also known as frame frequency, is measured as frames per second in videos like movies and TV to describe the number of still images displayed onscreen every second.
Theoretically, the more frames per second, the higher speed of playback, thus a smoother and more real the motion looks.
Resolution , also called screen or display resolution, is used to describe the density or the number of the pixels displayed in each dimension on the screen.
Generally speaking, we use width and height to define the total number of pixels. For instance, 320 x 240 means the width has 320 pixels while the height has 240 pixels. Therefore, the number add up to 76800 pixels.
The higher the resolution, the better quality the video you will get. That is to say, you can get more details and information through a clearer image.
Although high quality video like 4K, 1080p and 720p gives you the best viewing experience, but sometimes low quality video such as 320p and 480p is needed when you don't have enough storage space on your devices or you don't want to wait too long for the movies to be downloaded.
Related Article: How to DownScale a MP4 Video from 4K to 1080p or 720p
Aspect ratio, in layman's words, is the ratio of a image's width to its height. Let me give an example. 4:3 means 4 units in width and 3 units in height.
The two commonly used aspect ratio are 4:3 and16:9. However, there are other aspect ratio to meet people's needs: 5:4, 16:10, 21:9
If you want a comfortable viewing experience, it is advisable to base the aspect ratio of a video on that of the screen. A mismatch will result in something called letterboxing.
Video & Audio Bitrate
Bitrate is measured as bits per second, primarily used to tell you how many bits have been dealt with every second. To put it simply. If the bitrate of the video/audio file is 1Mbps, it means 1 million bit rates are transited or used for one second of the video/audio.
Higher bitrate means higher video quality. That is to say, you need higher bandwidth and more space to transfer more data per second.
Likewise, as for audio file, higher bitrate translates into better acoustic effect, ensuring high-fidelity.
We use the term "Sample Rate" to be representative of the number of samples extracted from the continual signal of the audio file every second. Usually, the measure unit for sample rate is HZ per second.
As a rule, higher sample rate means better sound effect, thus getting closer to lossless sound quality, but it is not always the case. Normally, 44.1kHz is embraced by most of the audio formats.
Channel, also defined as sound channel, is the audio signal during sound recording or reproduction.
Sound channel falls into two main category: Mono and Stereo.
Mono channel system is mixing all the possible sound signals and produce them through one single channel.
Stereo system uses more than one channel, allowing you to locate the position for each sound.
A container is a metafile format that holds audio, video and codec files and other data compressed by standardized codecs into one place. It's capable of wrapping any kind of data but does not describe how data or metadata is encoded.
Commonly used containers: MP4, AVI, WMV, MKV, VOB, MTS, M4V, FLV, SWF, MP3, WAV, FLAC