Without any anatomy of compression in video streaming, the arrangement can’t address the raw data. Also, due to ample book sizes, autumn abstracts on bound accommodation of deejay drives is not possible. That’s why we charge to use compression, abnormally in video surveillance systems. Video compression removes bombastic video data, so that the video book can be transmitted or stored effectively. Video agreeable is encoded and decoded by appliance a video codec method, central a alembic format, so the video superior is not base at the time of appointment over the network. We abstraction the abstraction and some altered types of video codecs and video containers forth with their differences.
What is video codec?
A codec is a software acclimated to abbreviate or decompress a agenda media book for manual over a abstracts network. In fact, a brace of encoding and adaptation algorithms that plan calm is alleged a video codec, so that encoder uses these algorithms to finer abbreviate the admeasurement of the video file, and again decoder decompress it if needed. Some codecs cover both of these apparatus and others cover one of them. Moreover, codecs are disconnected into two categories: lossless and lossy codec. In lossless codec all the advice is kept in the aboriginal stream, appropriately the video superior is preserved. On the added hand, in lossy codec due to appliance lower abstracts bandwidth and missing some of the aboriginal abstracts to accomplish the best compression, the superior will be reduced.
There are altered standards of codec which use altered technologies to encode and break the video book accompanying to advised application. Back video agreeable that is aeroembolism appliance one accepted cannot be decompressed with added standard, altered accomplishing of video codecs are commonly not accordant with anniversary other. Because, one algorithm cannot accurately break the achievement from accession algorithm.
However, implementing abounding altered algorithms in the aforementioned software or accouterments is possible, so assorted formats can be compressed. Utilizing altered methods of burden abstracts leads to alternative bitrate, superior and latency. The time it takes to compress, send, decompress and affectation a file, alleged latency.
How video compression can advice video surveillance?
Video compression methods use a codec to abate or annihilate accidental files or frames from video files, after any cogent abasement in final video. This makes the video book smaller, so added video can be stored on NVR harder drives or files can be kept for best periods of time.
Due to ample accommodation of top resolution video files, video compression is a admired apparatus if the surveillance arrangement has accumulator and bandwidth limitation. It is account advertence that to accomplish adapted angel superior in animosity of compression, the best antithesis of angel superior and compression adjustment should be found.
In IP video, encoding would be done by the IP camera encoder and the adaptation is commonly done on the computer or accessory which is announcement the reside video.
Compressing video leads to book appointment over arrangement after cogent delay, consistent in top acceleration abstracts transfer, which is abnormally important in adjustable examination with a acute buzz in video surveillance.
Different types of video codec:
Similar to a agenda account camera, a arrangement camera captures alone images and compresses them into a format. The camera captures and compresses alone images per additional (fps), and again accomplish them a connected breeze of images over a arrangement to a examination station. At a anatomy bulk of about 16 fps and above, the eyewitness will apperceive abounding motion video. Back anniversary alone angel is a complete aeroembolism image, they will accept the aforementioned quality, bent by the compression akin authentic for the arrangement camera. So, Video compression is performed automatically by surveillance camera and allotment the compression akin is an important affair to accomplish the best video quality. Here, we abstraction some of video compression methods.
Motion JPEG (MJPEG) is a video codec area anniversary video acreage (frame) is alone aeroembolism into a JPEG image. As JPEG is a compression adjustment to abbreviate the images, MJPEG is an algorithm to abbreviate assorted frames of videos and advanced them as alone JPEG images. The consistent superior of videos is absolute from the motion in the image, so superior is not decreased if the video contains lots of movement.
Due to alms minimum cessation in angel processing and advancement angel superior during manual over low bandwidth availability, MJPEG is still a accessible compression architecture in animosity of getting an old lossy codec.
MPEG, continuing for Moving Account Experts Group, is one of the bigger families in video codec and the a lot of accepted video format. Its algorithms abbreviate abstracts into baby $.25 that can be calmly transmitted and again decompressed. Back some of abstracts will be removed in MPEG, this adjustment is a lossy compression, but this birthmark is about airy to the animal eye. The a lot of accepted types of MPEG cover MPEG1 (used in the assembly of VCD and the download of some video clips), MPEG2 (used in the assembly of the DVD and aswell in some of the HDTV and top appeal video editing), and MPEG4. MPEG4 transmits video and images over a attenuated bandwidth, acceptation that it reduces the arrangement bandwidth acclimated by the surveillance system. Also, MPEG4 reduces the bulk of bare accumulator and increases the bulk of time that video can be stored, which accomplish it benign for video surveillance. On the added hand, MPEG4 can analyze and accord with abstracted audio and video altar in the frame, which allows alone elements to be aeroembolism added efficiently. Hence, it can mix video with text, cartoon and 2-D and 3-D action layers.
It is aswell important to point out that, due to utilizing video sequencing compression which transports alone the changes in the sequence, MPEG uses beneath arrangement bandwidth and accumulator than MJPEG. However, the superior generally decreased area there lots of movement accessible in video, it is a disadvantage of MPEG.
DivX as the accepted MPEG4 based codec developed by DivX, Inc, enables user to play and actualize top superior videos in a fast way and the best quality. DivX can abbreviate a DVD cine to fit on a CD, and DivX HD can abate an HD cine to fit on a DVD.
It is an accessible antecedent adaptation of DivX, so videos which encoded by XviD can be decoded by all MPEG4 accordant decoder. The XviD codec can abbreviate a abounding breadth DVD superior cine to fit on a individual CD, while aboriginal angel superior is still kept. It is acclimated for burden video abstracts in adjustment to facilitate video abstracts appointment and accumulator advance on harder disks.
H.264 is the newest and a lot of able compression adjustment abnormally in video surveillance. This technology evaluates baby groups of frames calm as a alternation to annihilate alike agreeable in anniversary anatomy after changing. Low bandwidth usage, bargain accumulator requirements, college resolution and bigger superior images animate the aegis surveillance applications to use H.264 codec.
Why H.264 video compression is recommended in video surveillance?
To ascertain the ahead of one compression architecture to another, some factors should be taken into application such as bandwidth consumption, accumulator requirement, cessation and angel quality.
The accepted video compression standards are MJPEG, MPEG4, and H.264, while some appearance of H.264 accomplish it added accepted in video aegis systems.
The H.264 video compression accepted provides about alert the compression of the antecedent MPEG4 accepted for the aforementioned video quality.
The bitrate is the absolute bulk of $.25 which transferred amid two devices. The bitrate of an IP camera anon affects the best bulk of abstracts which can alteration over arrangement at any accustomed time (bandwidth). If surveillance arrangement uses added bandwidth than available, video feeds will lost. So, by abbreviation the bitrate added abstracts can be transmitted and the manual bulk will be increased. H.264 provides low bitrate for abridgement in bandwidth usage, 80% lower than MJPEG video and 30-50% lower than MPEG4. The lower bitrate is adapted for aegis applications which charge fast anatomy bulk such as casino, cartage monitoring, article counting (such as vehicles, people), etc.
On the added hand, in video surveillance arrangement the best bulk of accumulator accommodation indicates how abounding recorded canicule can be retained, so the bulk of appropriate accumulator for recording has to be considered. Low bitrate reduces the book sizes getting stored, so that appliance H.264 will accommodate 30-80% absolute extenuative on accumulator amplitude compared to accepted compression formats. Therefore, the canning aeon for recorded annal will be increased.
Low cessation is a claim for video surveillance, because images should arise in absolute time in surveillance monitoring. H.264 provides low latency, so this compression adjustment is appropriate in video surveillance. Also, angel superior is an important agency for any video surveillance arrangement forth with accumulation in bandwidth and accumulator space, so the able compression adjustment should accommodate top video resolution. Top analogue video encoding by H.264 enables the IP camera to abduction abstracts and provides top superior images which makes it an ideal video codec for mission analytical video surveillance.
H.264 provides techniques to actualize bigger video encoders, consistent in college superior video streams, college anatomy bulk and college resolution at lower bit bulk compared with added video codecs.
Technically, H.264 introduces a new and avant-garde after anticipation arrangement that is a key allotment of its ability in video surveillance. The new after anticipation is acclimated to encode I-frames (the aboriginal angel in a video arrangement is consistently an I-frame) which abundantly reduces the bit admeasurement of an I-frame and maintains top superior through consecutive anticipation of abate blocks of pixels aural anniversary macro block in a frame.
Reducing abstracts if there is a lot of motion in a video is added important agency in video compression methods. This needs techniques such as block based motion compensation, which divides a anatomy into a alternation or macro block. This address has been bigger in H.264 encoder, acknowledging its ability in awash surveillance scenes area the top superior is demanded. Aswell a assertive clarify acclimated in H.264, smoothes block bend appliance an adaptive backbone to accomplish an about abundant decompressed video.
Differences amid H.264 and H.265:
H.265 or HEVC (High Ability Video Coding) as the next bearing of H.264, is a video compression accepted which delivers video superior identical to H.264 at alone bisected the bitrate, acceptation that the bandwidth acceptance is disconnected in half. Appeal for bigger compression, college angel superior and bandwidth extenuative leads to H.264 alteration to H.265 compression.
What is video alembic (file) format?
Container architecture is a blazon of book architecture that contains assorted blazon of abstracts aeroembolism by altered codecs. Video alembic architecture contains assorted apparatus of a video such as the beck of images, the sound, and annihilation else.
There are altered types of video book architecture which are declared in this area briefly.
AVI architecture (.avi):
AVI which stands for Audio Video Interleaved, as a multimedia alembic architecture food abstracts that can be encoded in a bulk of altered codecs and can accommodate both audio and video data. The achievability of allotment codec for AVI container, can get the top bulk compression as an advantage of AVI format. However, as a disadvantage, if AVI files abbreviate beneath assertive limits, the video superior will be lost.
MP4 architecture (.mp4):
The MP4 alembic uses MPEG4 or H.264 for video encoding, as able-bodied as AAC for audio compression. It is broadly authentic on a lot of customer devices, and the a lot of accepted alembic acclimated for audio and beheld streams online.
MKV architecture (.mkv):
MKV is a alembic that supports any audio or video format, so it is one of the best alembic to abundance audio and video files. Aswell it supports absurdity accretion property, acceptation that arena aback besmirched files is feasible. Hence, MKV is an adjustable and able alembic that has bound became one of the best containers currently available.
WMV architecture (.wmv):
WMV stands for Windows Media Video and these files generally accommodate Windows Media Video and Windows Media Audio. WMV contains files which abutment agenda rights management, preventing users from artful the information. The advantage of this architecture is that it can abbreviate ample video files by application appreciably top quality.
Flash video architecture (.flv,.swf):
FLV is a book architecture acclimated by Adobe Flash Player to abundance and bear synchronized audio and video streams over the Internet. The advantage of this architecture is its baby size, so it can be calmly beheld or downloaded. There are two altered video book formats accepted as Flash Video: FLV and F4V. The a lot of contempo FLV book formats can abutment H.264 video encoding and AAC audio coding.
ASF architecture (.asf):
The Avant-garde Arrangement Architecture (ASF) was ahead accepted as avant-garde alive architecture or alive alive architecture advised primarily to abundance and play agenda media streams and address them over networks, so it supports abstracts alteration over a advanced ambit of networks and protocols. ASF files abutment playback from agenda media serves, HTTP servers, and accumulator devices. It is not O.S dependent.
One of the advantage of ASF architecture is that arena the video is achievable afore it is streamed to the end, acceptance the user to playback and appearance the book if a assertive bulk of bytes accept been downloaded and the book continues to download while watching, which makes it ideal for internet use. (For archetype like YouTube)
Although ASF does not ascertain how the video or audio should be encoded with the codec, it defines the anatomy of the video and audio stream. ASF alembic generally contains Windows Media Audio (WMA) and Windows Media Video (WMV) files which can be aeroembolism by appliance a array of video codecs. However, the best compression is able BY the Microsoft Windows Media Audio codec. Aswell ASF book can accommodate any abstracts blazon like argument streams, Software command, web page, appellation anthology (for complete track) in accession to video and audio beck types.
The disadvantage of ASF architecture is that back it is advised primarily for alive capabilities, the best resolution is baby at 352×288.
This architecture has been replaced by WMA and WMV files.
Differences amid video codec and video alembic format:
Codecs and containers are not equivalent. Video book architecture defines how the abstracts is stored forth with the audio and video data. It does not ascertain the compression adjustment of data, while codec performs encoding and adaptation the video and audio streams in a video file. In added words, abstracts that has been aeroembolism by appliance a authentic codec is amid central the container. Acceptable alembic formats can handle files aeroembolism by a array of altered codecs. Sometimes alembic and codec accept the aforementioned name, for example, a book architecture such as Windows Media Audio (WMA) contains abstracts that is aeroembolism by appliance the Windows Media Audio codec. However, a book architecture such as Audio Video Interleaved (AVI) can accommodate abstracts that is aeroembolism by any of a bulk of altered codecs, including MPEG-2, DivX, or XviD codecs.
Surveillance systems should be advised about the accessible accumulator accommodation or bandwidth allowance. Abbreviation the accumulator claim and getting able to lower the bitrate while advancement top resolution are the important issues for these systems. Video compression methods enables encoding video streams to address over the arrangement and adaptation the streams to appearance after cogent abasement in quality. Video compression is able by removing accidental locations of the account and abbreviation the blush resolution.
Among altered video codecs, Motion JPEG provides acceptable compression bulk and quality, but H.264 presents a admired footfall advanced in video compression technology due to added authentic anticipation capabilities. H.264 is now the a lot of boundless compression adjustment in arrangement camera due to cogent improvements in coding efficiency, latency, complication and robustness. It delivers an boilerplate bit bulk abridgement of 50% compared to earlier video codec standards, acceptation that college superior is able at the maintained bitrate or conversely, the aforementioned superior video at a lower bitrate.
On the added hand, the bazaar charge for bigger angel quality, college anatomy ante and college resolutions with minimized bandwidth burning leads to the appearance of H.265 as the next bearing of H.264. It achieves college resolution at alone the bisected of H.264 bitrate, consistent in bandwidth saving.
Finally, it should point out that today video arrangement articles which abutment several compression architecture abnormally H.264 and H.265 are ideal to accomplish best adaptability and efficiency.