What is the avchd format

In the advertising brochures, the new camcorders are advertised with captivating colors, unattainable sharpness and other great features. These cameras record in AVCHD format. Here I am simply trying to explain the advantages and disadvantages of this format.

AVCHD - in English A.dvanced V.ideo C.odec High D.efinition - in German something like extended, high-resolution video algorithm - is a process to store the video images compressed in digital form on a medium (hard drive, memory chip). We know the corresponding codecs, e.g. MPEG 1, 2 or 4. The MPEG series are so-called container formats in which the actual data stream is stored. The container describes which codec is inside, how long the file is, etc. The MPEG 2 format is used on conventional DVDs.

MPEG 4 is originally used by Apple's Quick Time. This format has been developed several times. At the moment the exact format is called AVC / H.264, with the name H.264 describing the video compressor. This codec generates the compressed video film and packs it into the MPEG 4 container, which in turn is placed in the MPEG 2 container. So when we use AVCHD, we use an MPEG 4 format (Version 10 or Part 10) with an H.264 compression algorithm in the background.

In addition to the improved compression level, there are some other major differences to the standard DVD or PAL format:

Our analog TV picture, which we are confronted with every day, only offers a 'height' of 576 lines. If you get very close to your CRT TV, you can count the lines. The super duper large TFT televisions also use this number of lines. Therefore, the larger the TFT, the more blurred the images. With AVCHD we will have a wide range of formats that can be recorded in the future. We can use 720 lines or 1080 lines. We perceive a large part of the sharpness effect of the images with the number of individual images. If a few individual images are shown per second, the image will become blurred. The more individual images can be displayed, the sharper we perceive the video material. Therefore, in addition to the designation of the lines to be displayed, there is also a value for the images to be displayed, namely with 720 lines 30, 25 or 24 frames / s, with 1080 there are 24 frames per second.

So that the whole thing doesn't get too easy, there's the story with the frames and the fields. Our standard television program works with 50 fields / second. This means that only a picture that looks like an open jarlousia is displayed. Next comes the next field and fills the open strips. Then another field appears and replaces the first. etc. So a total of 50 fields are displayed per second. This field method is supported by the i like interlaced made clear. This image process tends to flicker and blur, which is why we should refrain from this format. The product descriptions then contain information such as 720 / 50i

Another option is the full screen. Here, not every second line of an image is displayed, but always a full image. This is called then Progressive and will with p abbreviated. Because only full images are displayed, only half of the images to be displayed are required. That is the process that brings sharpness. The product descriptions then contain values ​​such as 1080 / 25p.

You can use this technology if you also have so-called FULL HD playable devices. The first thing you need is a TV that has the right characteristics. (Full HD READY). Then you either need your video camera, which you connect directly to the television using an HDMI cable, or you have a Blue Ray disc player that can play the AVCHD or Full HD films on a DVD-like Blue Ray. Of course you have to get your video film from the camera onto the Blue Ray somehow. To do this, use your high-performance computer with appropriate editing software that can also handle AVCHD data streams.

If you have all of these devices in the house, you can fully enjoy high-resolution video material you have shot yourself.


K. Schirmacher