Video compressie technieken zijn essentiel voor video editing op de PC. Een PAL video signaal (720x575 pixels, 25 beeldjes per second, 24bit kleuren) is ongeveer 28 MB/sec -> 100 GB per uur. Als video dus niet gecomprimeerd zou worden zou er maar 3 minuten video op een DVD kunnen van 4,4 GB. Ook de verwerkingscapaciteit en harde schijfruimte van PCs is beperkt.
Een erg veel gebruikt formaat voor het editen van video op de PC is DV formaat. Dit is 3,6 MB/sec groot en per beeldje apart gecodeeerd. Hiermee kan makkelijk iedere afzonderlijk beeld bewerkt worden. Voor distributie van het uiteindelijke formaat is 3,6 MB/sec nog steeds aan de grote kant (er kan dan bijvoorbeeld maar ongeveer 25 minuten op een DVD). Daarom zijn er nog een scala aan andere formaten beschikbaar hiervoor. Een van de meest gebruikte is MPEG2. Dit formaat wordt in bijna alle DVDs toegepast. Daarnaast zijn er nog codecs zoals MPEG1, MPEG4, DIVX, XVID, HUFFJUV, etc, etc. Zie hieronder meer.
| Codec / standard | Speelt af op |
| MPEG-1 | PC > 100 MHZ |
| MPEG-2 | PC > 350 MHZ |
| MPEG-4 / DIVX | PC > 350 MHZ |
| VIDEO-CD (MPEG-1 codec) | Video CD player, DVD player, PC |
| Super Video CD | DVD player (some, see compatabiliteitslijst), PC |
| Extended Super Video CD | DVD player (some, see compatabiliteitslijst), PC |
| DVD (MPEG-2 codec) | DVD player, PC met DVD-ROM drive |
| Codec / standard | comments |
| M-JPEG (motion JPEG) | Vergelijkbaar met DV formaten. Werd eind 20e eeuw veel gebruikt. Ieder bestand wordt onafhankelijk van de andere gecomprimeerd. Data rate 3-6 MB/sec. |
| Huffyuv | Lossless snele kompressie for beste kwaltieit video. Data rates ongeveer 10 MB/sec. Gratis codec. |
Tabel waarin in 1 oogopslag te zien is hoeveel video er op een CD of DVD past bij welke bitrate (HTML) (XLS)
How does your video look in a certain codec or bitrate? See the following link for some examples:
This codec is used mainly for capturing and editing analog video. Typical data rated for M-JPG is 3-6 MB/sec, which is quite big for distribution. The big advantages of M-JPEG are the good quality and that each frame is compressed independent from the others, which makes editing easy. Most capture cards make use of hardware M-JPEG compression and decompression techniques. This means that each frame is compressed using the JPEG algorithm. These algorithms are specific to the hardware board.
Software to use M-JPEG compression without the hardware capture cards installed:
Huffyuv is a very fast, lossless Win32 video codec. "Lossless" means that the output from the decompressor is bit-for-bit identical with the original input to the compressor. "Fast" means a compression throughput of up to 38 megabytes per second on my 416 MHz Celeron. Huffyuv is intended to replace uncompressed YUV as a video capture format. It is fast enough to compress full-resolution CCIR 601 video (720 x 480 x 30fps) in real time as it's captured on my machine. Huffyuv also supports lossless compression of RGB data, so it can be used for the output of programs like VirtualDub.
MPEG-1 is a pretty old compression standard. The big advantage of MPEG-1 is that is supported on virtually any PC, Video CD player and DVD player (in the latter two, in the video CD format).
Currently (2003 Jan) I recommend
TMPGEnc
to encode video files in MPEG1. This is
freeware and has very good quality. The disadvantage is that is has no plug-in for Adobe
Premiere, so you need to export the AVI file first and afterwards convert the AVI file to
MPG-1. In this process you need more diskspace. If you want to use a plug-in for Premiere I can recommend the
Panasonic Encoder
to create the MPG1 file.
MPG files can be edited using the
Darim M-Editor or
MPG-VCR.
read more:
MPEG-2 is for high quality full screen broadcast quality video. It has bitrates of about 5-30 Mb/sec.
Very good (budget) software encoders are TMPGEnc (Tsunami MPeG Encoder) and the Ligos Encoder. Read more on encoder tests:
Other MPEG-2 Links
See also DVD
MPEG-4 is designed for very low bitrates, like <64 Kb/sec. Especially for distributing video over the internet. Nowadays it is also used a lot to encode good quality video: i.e. a full DVD can be put on 2 normal CDs with the MPEG-4 format in good quality (ratio 110 KB/sec).
Windows media tools can be used to create MPEG-4 files.
Windows Media Player 6.4 or higher can play MPEG-4 video.
More info:
DIVX is the MP3 of the video! DIVX is based on MPEG-4. It is a very popular codec to distribute video's over the internet. It is possible with this codec to put a complete movie on one CD (650 MB). Note that you need a powerful CPU to play DIVX video (350 MHZ or faster).
My favorite software package to create DIVX movies is Gordianknot (you can find this tool at http://www.doom9.net )
Many codecs in one place
http://www.softnews.ro/public/cat/11/2/2/ DV (Digital Video) A widely accepted, digital standard for video. The camera
does the digitizing. 1-1 transfer to computer without losing quality.
Summary of technical specs: video: Compressed to 25Mb/sec, resolution: 720x576
(PAL) or 720x 480 (NTSC), audio: 2 ch @ 48 kHz @16 bits or 4 ch @ 32 kHz, 12
bits (more in-depth technical details, see
http://www.adamwilt.com/DV-tech.html)
There are 2 types of DV, Type 1 and 2.
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