Video File Formats and Codecs

Question 1

Video file types consist of _______ and _________
.

Answer 1

Video file types consist of codecs and containers.

Question 2

Codecs

What is a codec?

3 points

Answer 2

• Codecs are compression technologies
• and have two components, an encoder to compress the files,
• and a decoder to decompress.

Question 3

Codecs

What sort of data are codecs used for?

4 points

Answer 3

There are codecs for
* data (PKZIP),
* still images (JPEG, GIF, PNG),
* audio (MP3, AAC)
* and video (Cinepak, MPEG-2, H.264, VP8).

Question 4

What are the 2 types of Codecs?

Answer 4

Lossy & Lossless

Question 5

What is the difference between Lossy & Lossless Codecs?

Answer 5

Lossy Codecs result in a decompressed file that is of lower quality than the original, but they are smaller files.
Lossless codecs create a file with no loss in quality or data, but the files are larger.

Question 6

The more you compress a file, the more ____ you lose

Answer 6

data

Question 7

Lossy compression technologies use two types of compression, ________ and _________ compression.

Answer 7

Lossy compression technologies use two types of compression, intra-frame and inter-frame compression.

Question 8

What is intra frame compression?

4 points

Answer 8

Intra-frame compression is essentially
* still image compression applied to video,
* with each frame compressed without reference to any other.
* For example, Motion-JPEG uses only intra-frame compression,
* encoding each frame as a separate JPEG image.

Question 9

What is inter frame compression?

5 points

Answer 9

inter-frame compression uses:
* redundant (repeated areas) between frames to compress video.
* eg, in a talking head scenario, with a static BG Inter-frame techniques store the static background information once,
* then stores only the changed information in subsequent frames.
* Inter-frame compression is much more efficient than inter-frame compression,
* so most codecs are optimized to search for and leverage redundant information between frames.

Question 10

Explain how codecs with key frames and deltra frames work, and explain is it lossless or not.

Answer 10

• Key frames stored the complete frame and were compressed only with intra-frame compression.
• During encoding, the pixels in delta frames were compared to pixels in previous frames,
• and redundant information was removed.
• The remaining data in each delta frame is also compressed using intra-frame techniques
• as necessary to meet the target data rate of the file.
• The 4 delta frames stores only the blocks of pixels that have changed.

Key Frames and Delta Frames

Question 11

explain why talking head videos encode at much higher quality than soccer matches or NASCAR races.

Answer 11

Because a talking head has large redundancies (static areas) that can be easily efficiently compressed with inter-frame compression.
* Where are soccer or nascar TV has very few static areas meaning it is much harder to compress

Question 12

What does MPEG stand for?

Answer 12

The Moving Pictures Expert Group (MPEG)

Question 13

What is MPEG-2

Question 14

How is a Codec used?

2 points

Answer 14

It can :
* digitize and compress an audio or video signal for transmission

• and convert an incoming signal to audio or video for reception

Question 15

In order to compress your video a files must have a coresponding ____?

Answer 15

codec!

Question 16

The codec of your original ____ file is often determined by your ____ or _____ _______, which you may or may not have _____ over in your ________ settings.

Answer 16

The codec of your original video file is often determined by your camera or screen recorder, which you may or may not have control over in your camera settings.

Question 17

What is the most common codec?

Answer 17

H.264

Question 18

What is h.264 used for ?

Answer 18

h.264, which is often used for high-definition digital video and distribution of video content.

Question 19

What does bit rate refere to?

Answer 19

Bit rate refers to the amount of data stored for each second of media that is played.

Question 20

What impact does bit rate have on compression and image quality?

Answer 20

The higher the bit rate, the less compression, which results in higher quality overall.

Question 21

______ files on their own may be no ______, but when _______ by the size of the _______, it can cause _________ problems that affect ________ service providers and users.

Answer 21

Larger files on their own may be no problem, but when multiplied by the size of the audience, it can cause bandwidth problems that affect internet service providers and users.

Question 22

What is a container?

Answer 22

A container is like a simle box, its the file that contains:
* your video,
* audio streams,
* and any closed caption files as well.
* meta data

Question 23

It’s common for a ——- to be called a —- ———- since they are often seen at the — of file names (e.g. filename.—).

Answer 23

It’s common for a container to be called a file extension since they are often seen at the end of file names (e.g. filename.mp4).

Question 24

Name 3 common Video Container Formats

Answer 24

MP4
AVI
MOV

Question 25

MP4
The MP4 container format is supported by just about every ——. It can contain any —— format version and —–. ——— videos are usually in this common video format.

Answer 25

MP4
The MP4 container format is supported by just about every device. It can contain any MPEG-4 format version and H.264. YouTube videos are usually in this common video format.

Question 26

AVI – Audio Video Interleave
This is one of the —— video containers and it —– used very often anymore, but it’s still widely ———- and a lot of existing ——- is in AVI. The number of —— that can be used in the AVI ——– is massive, which is another reason you’d get into cold sweats trying to get an AVI file to play back in the good old wild west days of digital

Answer 26

AVI – Audio Video Interleave
This is one of the oldest video containers and it isn’t used very often anymore, but it’s still widely supported and a lot of existing content is in AVI. The number of codecs that can be used in the AVI container is massive, which is another reason you’d get into cold sweats trying to get an AVI file to play back in the good old wild west days of digital

Question 27

MOV
The MOV container is associated with the —– ——- —- ——- and is its ———— format. Inside a MOV file you are most likely to find ——– video data. Which is why, in most cases, you can rename a — file to an — file and it will work just the same.
The main difference between MOV and MP4 files is that MOV files sometimes have —- ———–. This prevents sharing and playing by ————- users.

Answer 27

MOV
The MOV container is associated with the Apple QuickTime Player and is its in-house format. Inside a MOV file you are most likely to find MPEG-4 video data. Which is why, in most cases, you can rename a MOV file to an MP4 file and it will work just the same.
The main difference between MOV and MP4 files is that MOV files sometimes have copy protection. This prevents sharing and playing by unauthorized users.

Question 28

These days, almost all —– is ——– using one of a small number of ——-.

Answer 28

These days, almost all video is encoded using one of a small number of codecs.

Question 29

H.264 – Advanced Video Coding
H.264 is by far the most ——– video codec at the time of writing. With just over — of all video offered in this common video format. Because H.264 is so popular, most devices (such as smartphones and smart TVs) have ——- ——– built in to decode H.264 video without putting any strain on the device’s —- ——–. Which is why even bottom-end ————– can play HD video without breaking a sweat.

Answer 29

H.264 – Advanced Video Coding
H.264 is by far the most popular video codec at the time of writing. With just over 90% of all video offered in this common video format. Because H.264 is so popular, most devices (such as smartphones and smart TVs) have special hardware built in to decode H.264 video without putting any strain on the device’s main processor. Which is why even bottom-end smartphones can play HD video without breaking a sweat.

Question 30

H.265 – The High Efficiency Video Coding
(HEVC) format of video compression has revolutionized —– ———, It’s designed to be the successor to —— and in general uses — to — less bandwidth to provide the same ——– or better ——— at the same bandwidth levels.

H.265 is finding great success in the world of streaming, but unlike H.264 there aren’t many devices that have ——- ——— decoding components for this codec. So while it will save plenty of ———- and —— —— space, it will give the target device a real ——–. As with H.264, this is likely to change over time, but for now you should keep its ——— ——– in mind before choosing to use it.

Answer 30

H.265 – The High Efficiency Video Coding
(HEVC) format of video compression has revolutionized video streaming, It’s designed to be the successor to H.264 and in general uses 25% to 50% less bandwidth to provide the same quality or better quality at the same bandwidth levels.

H.265 is finding great success in the world of streaming, but unlike H.264 there aren’t many devices that have special hardware decoding components for this codec. So while it will save plenty of bandwidth and hard drive space, it will give the target device a real workout. As with H.264, this is likely to change over time, but for now you should keep its limited support in mind before choosing to use it.

Question 31

MPEG-4
MPEG-4 can get a little ———-. It’s also a very —— video codec, but MPEG 4 Part 10 is actually the same as ——.

Early versions of MPEG-4 (e.g. Part 2) use older algorithms that are much less efficient in terms of space for the same level of quality. —– has essentially replaced —–with a new naming convention.

Answer 31

**MPEG-4
MPEG-4 can get a little complicated. It’s also a very common video codec, but MPEG 4 Part 10 is actually the same as H.264.

Early versions of MPEG-4 (e.g. Part 2) use older algorithms that are much less efficient in terms of space for the same level of quality. H.264 has essentially replaced MPEG-4 with a new naming convention.

Question 32

MP3 – MPEG Audio Layer-3

Since this format can squeeze CD-quality audio to roughly a —– of its size without losing too much ——-, it’s been a ——– of digital audio for years.

Regardless of which video —– a given video ———- uses, there’s a good chance the audio itself is in — ——.

Which also has various levels of ———-, with the happy medium usually falling around the — to —- Kbps level.

Answer 32

MP3 – MPEG Audio Layer-3

Since this format can squeeze CD-quality audio to roughly a tenth of its size without losing too much fidelity, it’s been a mainstay of digital audio for years.

Regardless of which video codec a given video container uses, there’s a good chance the audio itself is in MP3 format.

Which also has various levels of quality, with the happy medium usually falling around the 128 to 196 Kbps level.

Question 33

WAV – Waveform Audio Format

The “wave” format has been around for —- and is (in general) an ———— digital audio file that represents the ————- recording waveform ————.

——- Files

At the same quality settings as – audio, a WAV file should take up roughty as much space as a –. While it’s not particularly common, a video can contain — audio as well.

Answer 33

WAV – Waveform Audio Format

The “wave” format has been around for ages and is (in general) an uncompressed digital audio file that represents the original recording waveform precisely.

Large Files

At the same quality settings as CD audio, a WAV file should take up roughty as much space as a CD. While it’s not particularly common, a video can contain WAV audio as well.