Explaining Digital Video: Formats, Codecs & Containers

[00:01] [Music]

[00:12] welcome to another video from explaining

[00:14] computers

[00:17] this time i'm going to talk about

[00:19] digital video

[00:20] formats to do this i also need to

[00:23] explain

[00:23] digital video codecs and containers

[00:27] so let's go and get started

[00:35] digital video files can have many

[00:38] different file extensions

[00:40] including mp4 mov and

[00:43] mxf however the first thing to

[00:46] understand about digital video formats

[00:48] is that they're not defined by their

[00:50] file type

[00:51] this makes digital video formats far

[00:54] more complex than for example

[00:56] image formats where you can be certain

[00:58] that a jpg

[00:59] file is an image in the jpeg format

[01:04] rather than being defined by a file type

[01:06] a digital video format

[01:08] is a combination of a video codec and a

[01:10] container

[01:12] codec stands for coder decoder and

[01:15] refers to the algorithm used to

[01:17] digitally encode a video

[01:20] meanwhile a container is a digital box

[01:22] or wrapper

[01:23] used to store video streams in related

[01:25] content in a single

[01:26] file it is therefore digital video

[01:29] containers that can be identified by

[01:31] their file extension

[01:33] and not digital video formats

[01:37] today the great many video codecs and

[01:39] containers are in use

[01:40] with common codecs including h.264

[01:44] also known as avc h.265

[01:47] also known as hevc h.262

[01:50] also known as mpeg-2 part 2 mjpeg

[01:54] prores dnxhd and dnxhr

[01:59] common containers include mp4 avi

[02:03] mov mxf 3gp and 3g2

[02:07] and mts m2ts and ts

[02:10] there are many other digital video

[02:12] codecs and containers

[02:14] but the ones listed are those i'll

[02:15] explain in more detail

[02:17] later in this video

[02:21] as you probably gathered digital video

[02:23] is complex

[02:24] and can get somewhat confusing so

[02:28] to help us get our heads around the

[02:29] critical concept the video format being

[02:32] a combination of a codec

[02:34] and a container let's take a look at one

[02:36] of these

[02:37] a mini dv tape which was for years a

[02:40] common means of storing

[02:41] digital video however a minidv

[02:45] tape is a container and not a format as

[02:48] it can be used to store video

[02:49] in three different ways specifically a

[02:52] minidv

[02:53] tape like this one can store video

[02:55] encoded with the standard definition

[02:57] consumer dv

[02:58] codec with a professional standard

[03:00] definition codec called

[03:02] dv cam and with a high definition codec

[03:05] called hdv this means that it's

[03:08] impossible to look at the dv

[03:10] tape like this and to know its format

[03:13] and precisely the same is true when it

[03:15] comes to digital video

[03:17] files where the file extension indicates

[03:19] the container

[03:20] but not the videos codec

[03:29] digital video just like a reel of movie

[03:31] film

[03:32] is made up of a series of still frames

[03:35] a codec or coder decoder digitally

[03:38] encodes these frames

[03:40] with the term codec used to refer to

[03:42] both the software or hardware

[03:44] that performs the encoding operation as

[03:46] well as the algorithm

[03:47] it applies because videos contain a

[03:51] great deal of information

[03:52] most but not all codecs compress a

[03:55] video's frames

[03:56] to limit file size such compression can

[03:59] also

[04:00] be achieved in two ways known as

[04:02] intra-frame

[04:03] and interframe intra-frame compression

[04:07] compresses each frame individually in

[04:10] contrast

[04:11] inter-frame compression stores some

[04:13] complete frames as keyframes

[04:15] but all frames in between as delta

[04:17] frames which only contain

[04:18] incremental changes this allows

[04:21] interframe compression

[04:22] to produce smaller video files however

[04:26] intra-frame video is generally of a

[04:28] higher quality

[04:29] and is easier for a computer to edit as

[04:31] every frame is immediately accessible

[04:34] so if you are planning to edit your

[04:36] video it's best to shoot it using an

[04:38] intra-frame codec if possible

[04:42] common intra-frame codecs include mjpeg

[04:46] prores dnxhd and dnxhr

[04:50] as you may guess mjpeg stands for motion

[04:53] jpeg

[04:54] and stores each video frame or field as

[04:57] an individual jpeg image

[04:59] prores is a family of intraframe codecs

[05:02] created by

[05:03] apple which is widely used in

[05:05] professional video acquisition

[05:06] and production for different codecs in

[05:09] the prores family are named prores 422

[05:12] proxy which has the lowest data rate and

[05:14] quality

[05:15] up to prores 444xq which has a very high

[05:19] data rate

[05:20] and produces very large files

[05:24] dnxhd stands for digital non-linear

[05:27] extensible high definition and is a

[05:30] family of intra-frame codecs

[05:31] created by avid for professional video

[05:33] editing but now also used for

[05:35] acquisition

[05:37] as you may guess dnxhr is a higher

[05:40] resolution

[05:41] version of dnxhd supporting 4k video

[05:44] and above in common with prores dnxhd

[05:48] and dnxhr data rates and file sizes can

[05:51] get very large

[05:53] indeed

[05:56] one of the most popular codecs in use

[05:58] today is h.264

[06:00] also known as avc or advanced video

[06:03] coding

[06:04] h.264 was defined by the motion picture

[06:07] experts group

[06:08] or mpeg in part 10 of their standard

[06:11] mpeg-4

[06:14] most of the time h.264 is an interframe

[06:17] codec

[06:18] that produces relatively small video

[06:20] files by storing keyframes

[06:22] and the incremental differences between

[06:24] them however

[06:25] the specification allows h.264 to be

[06:28] used

[06:28] as an intra-frame codec and some

[06:30] professional video formats take

[06:32] advantage of this

[06:33] usually describing their codec as iframe

[06:36] h264

[06:40] a more recent and increasingly popular

[06:42] interframe codec

[06:43] is h.265 also known as hevc

[06:47] or high efficiency video coding this was

[06:50] also defined by the motion picture

[06:52] experts group

[06:53] in part two of their standard mpeg-h and

[06:56] can produce video with the same quality

[06:58] as an interframe h.264 codec

[07:00] with roughly half the data rate and file

[07:02] size

[07:04] however h.265 requires more computer

[07:07] power to encode and decode with h.264

[07:10] and so is not as easy to edit

[07:15] an earlier and still very important

[07:17] interframe codec

[07:18] is h.262 which was defined by the motion

[07:21] picture experts group

[07:23] in part two of their mpeg-2 standard

[07:26] h.262 is not as efficient as h.264

[07:30] or h.265 so produces much larger video

[07:34] files however it is still widely used

[07:37] for standard definition digital

[07:39] television broadcasts

[07:40] and dvds

[07:48] as noted earlier a digital video format

[07:51] is a combination of a video codec and a

[07:54] container

[07:55] here a container is a digital box or

[07:58] wrapper

[07:58] that is used to store a video stream as

[08:01] well as one or more accompanying audio

[08:03] streams

[08:03] and potentially other related content

[08:05] such as subtitles

[08:07] and metadata digital video containers

[08:11] include mp4 avi and

[08:14] mov mp4 was defined by the motion

[08:18] picture experts group

[08:19] in their mpeg-4 part 14 specification

[08:23] avi was developed by microsoft and

[08:26] stands for audio video into leave

[08:28] and mav was created by apple and is

[08:30] short for movie

[08:32] all three of these containers can store

[08:34] video encoded with many different codecs

[08:37] with mp4 and mov currently having the

[08:40] widest

[08:40] range of both professional and consumer

[08:43] applications

[08:45] more niche containers include mxf 3gp

[08:49] and 3g2 as well as mts m2ts

[08:53] and ts mxf stands for material exchange

[08:58] format

[08:58] and is a container used in professional

[09:00] video production and distribution

[09:03] meanwhile 3gp and 3g2 are containers

[09:07] developed by the third generation

[09:08] partnership project

[09:10] for use on mobile phones finally

[09:13] mts m2ts and ts

[09:16] were created for the avchd video format

[09:19] and blu-ray discs and stand for mpeg

[09:22] transport stream

[09:23] and peg 2 transport stream and transport

[09:26] stream

[09:26] respectively

[09:33] the codecs and containers we've just

[09:35] looked at can be combined

[09:37] to create a wide variety of video

[09:39] formats some of which

[09:40] are mainly used for recording and others

[09:42] for the delivery of final video files

[09:46] to provide just a few examples when it

[09:48] comes to acquisition

[09:50] videos recorded in the still relatively

[09:52] popular consumer format

[09:53] avchd which stands for advanced video

[09:57] coding high definition

[09:58] use the h.264 codec and either an mts

[10:02] or m2ts container the xavc-i

[10:06] and xavcl formats used on many sony

[10:09] cameras then store h.264 video in an mxf

[10:13] container

[10:13] while the closely related xavcs format

[10:17] uses an h.264 codec and an mp4 container

[10:21] many canon cameras shoot in a format

[10:23] called xfavc

[10:25] which again uses the h.264 codec and an

[10:27] mxf container

[10:30] often especially in the consumer arena

[10:33] video formats are not given a name

[10:36] for example most dslrs do not declare a

[10:39] format

[10:40] but use an h.264 or h.265 codec

[10:43] with either an mp4 or mov container

[10:47] similarly video captured on cameras and

[10:49] recorders that use a prores codec

[10:51] is typically described as being in the

[10:54] prores format

[10:55] and stored in a mod container whilst

[10:58] dnxhd

[10:59] and dnxhr codec videos are usually

[11:02] placed in either an fxf

[11:03] or mov file videos shot on smartphones

[11:08] also don't have a named format but are

[11:10] usually encoded with an h264 or h.265

[11:14] codec

[11:15] and stored in a 3gp 3g2

[11:18] or mp4 container on an android device or

[11:21] in a mav container

[11:22] on an iphone

[11:25] when it comes to the delivery of final

[11:27] digital video files

[11:29] once again we often lack specific format

[11:32] names

[11:32] although h264 and h.265 codex

[11:36] used with mp4 or mov containers are the

[11:39] most common

[11:40] in the consumer space and if you are

[11:43] ever in doubt

[11:44] render your final video using the h.264

[11:47] codec

[11:48] and an mp4 container as this is always a

[11:50] very safe bet

[11:52] as well as being the recommended upload

[11:54] format for youtube

[11:57] the professional delivery of final video

[12:00] files

[12:00] usually takes place in an mxf container

[12:03] using codecs that include prores dnxhd

[12:07] and dnxhr this said

[12:10] an intra-frame panasonic codec called

[12:13] avc

[12:13] intra is also very common

[12:17] indeed in october 2014 all uk

[12:20] broadcasters began using a format called

[12:22] as11dp for hd program delivery

[12:26] which uses the avc intra codec and an

[12:29] mxf container

[12:32] finally most cinemas these days project

[12:35] from a format

[12:36] called digital cinema package or dcp

[12:40] this uses an mjpeg codec and an mxf

[12:43] container

[12:44] so the mjpeg codec is not as rare

[12:48] as you may have imagined

[12:56] for the best part of a century the most

[12:58] stable and widespread motion picture

[13:01] format

[13:01] was this 35 millimeter film now

[13:06] technically we could argue that even the

[13:07] role of 35 millimeter film

[13:09] is a container and not a format because

[13:12] the

[13:12] frames on a roll of 35 millimeter film

[13:15] can be

[13:16] optically stretched to accommodate

[13:18] different aspect ratios and

[13:20] the vista vision format shot 35

[13:22] millimeter film

[13:23] horizontally and not vertically in order

[13:25] to get a bigger frame with higher

[13:27] resolution but for the most part

[13:30] for the best part of about a hundred

[13:32] years if you wanted to shoot

[13:34] high quality moving images with a good

[13:36] archive potential

[13:37] you chose the 35 millimeter film format

[13:41] today digital video reigns supreme

[13:45] online on television and in the cinema

[13:48] and as we've seen in this video there

[13:50] are a wide range of codecs and

[13:52] containers available

[13:54] which give us a bewildering array of

[13:56] digital video formats

[13:59] and deciding which one to shoot in to

[14:02] edit in to deliver in

[14:03] and to archive in is a very tricky

[14:06] decision

[14:07] but i hope at least in this video i've

[14:08] given you some useful

[14:10] information but now

[14:13] that's it from me and the role of 35

[14:15] millimeter film

[14:17] if you've enjoyed what you've seen here

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[14:23] you again

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