AVCHD

Advanced Video Codec High Definition (English Advanced Video Codec High Definition), short AVCHD is a format for digital video data. It was primarily designed for video recording with consumer and prosumer camcorders recording on digital media (such as SD card, flash memory, hard disk). It uses the H.264/MPEG-4 AVC codec and is in direct competition to the formats MiniDV and HDV particularly that uses the older MPEG-2.

  • 2.1 Video
  • 2.2 Audio
  • 2.3 Data Rate 2.3.1 specification limit
  • 3.1 Comparison with tape recorder
  • 3.2 Video Editing 3.2.1 stability
  • 3.2.2 computational effort
  • 3.2.3 Large Files

Emergence and dissemination

The Standard Advanced Video Codec High Definition was developed jointly by the company Matsushita (Panasonic) and Sony, and introduced on May 11, 2006. The two companies also hold the rights to AVCHD as a trademark.

On July 13, 2006 marked the beginning of licensing was announced. The format is currently also supported by Canon. Support from products of Pioneer, Samsung and Sharp has been announced. The licenses are issued for recording and playback devices, as well as for software.

AVCHD Lite

The presented on January 27, 2009 Standard AVCHD Lite is analogous in all specifications the AVCHD standard - with the only restriction that he is limited for video recordings on the row format with 720 lines (720p ), and hence the row format not supported for video recording 1080i. AVCHD Lite is initially intended for camcorders and digital cameras whose video recordings can be on each playback or recording device that corresponds to the AVCHD standard can transmit. The fact that of the corresponding standard AVCHD Lite recorded video during playback by up-scaling and video formats with higher number of lines can be generated (see, for example, line doubler ), the standard AVCHD Lite is not undermined.

This format requires processing at a less computation time due to the lower resolution.

Hardware

Sony, Panasonic and Canon have launched in 2006 first AVCHD camcorders on the market. Also, Blu -ray players support this format usually because the Blu- ray Disc format was chosen for the internal data structure of AVCHD on Sony and Panasonic. If AVCHD clips stored on DVD instead of Blu- Ray media, called this mini Blu -ray or AVCHD disc. The data are stored in 2.5 or later Universal Disk Format (UDF ) version on the discs. This can lead to reading problems on PCs, because only a corresponding UDF driver must be installed before the discs are readable ( currently applies to Windows XP and Linux).

Products, which can handle AVCHD content can be applied with a licensed logo (see figure). The Sony PlayStation 3 is ( as of firmware version 1.9) capable of playing AVCHD videos from a memory stick or an external hard drive, the size of the AVCHD files is limited to 4 GB by the lack of support of the NTFS file system. The WD TV HD Media Player can also play AVCHD video from an external USB hard drive, and it supports the NTFS file system, which files are larger than 4GB supported. 4GB be reached at HD recordings usually after about 40 minutes of recording.

Commercial area

Meanwhile, as both Panasonic and Sony camcorders have brought out, although using the AVCHD codec, however, be aimed at professional users. It is expected that this will replace the medium HDV camcorder, as now can also edit professional AVCHD Editing software and computational power of the computer used for editing is sufficient (see the section Video section). The companies market these camcorders under special brands.

AVCCAM

AVCCAM is the name of Panasonic broadcast professional video product line, which uses the AVCHD codec. This was previously listed as " AVCHD with professional features". In part, this [email protected] the AVCHD format is offered with maximum bit rate of 24 Mbit / s, which corresponds to an increase from Panasonic Consumer models / s are limited to a maximum bit rate of 17 Mbps. Other manufacturers such as Canon, JVC, and Sony offer 24 Mbit / s in their consumer camcorders.

NXCAM

NXCAM is the name of Sony's professional video product line, the AVCHD codec used (announced November 2009). NXCAM supports 1080i, 1080p and 720p recording modes of AVCHD with data rates up to 24 Mbit / s Audio can be recorded as uncompressed PCM audio recording. Unlike AVCCAM NXCAM does not support the standard frame rate for film 24p to 720p mode.

Software

The format is now supported by most manufacturers of video editing software.

Details of the specification

The Advanced Video Codec High Definition is based on the MPEG -4 AVC/H.264 standard (MPEG -4 Part 10). The first definition of this format is called AVCHD format version 1.0. The compressed video and audio content are stored in an MPEG -2 transport stream (usual file extension is. Mts for " MPEG Transport Stream "). The as a "transport stream " packed data have thus a kind of container, which makes it easier to be able to then read the binary data yet, if either file or transmission errors have happened or eg not defined for a GOP can be started with the reading, for example, if TS data are received by a television station, but you will change to undefined times on the channel.

Video

In addition to established television standards with 480 lines (see NTSC) and 576 lines (see PAL or SECAM) in the ratios 4:3 and 16:9 are also the modes 720p / ( 30/25/24 ), 1080i / ( 60/50 supported) and 1080p/24 in 16:9 aspect ratio. As a compression method for video signals MPEG-4 AVC/H.264 is used.

The specifications of the above providers there is an additional image resolution 1440 × 1080 for the 16:9 format, but which is not compliant with the H.264 standard, as it provides for the HD display in 16:9 only square pixels.

The video signals are recorded in the MPEG -4 data compression standard, and then to transfer them to an MPEG -2 transport stream. The playback is performed at a data rate of, for example, 6, 9, 13, 18 or 24 Mbit / sec (plus clay and metadata).

AVCHD uses a scalable compression method (MPEG -4 ) with different processing depth and provides an internal image structure with a group of pictures up to 15 frames (frames). The color scanning is performed in AVCHD with 8 bit, 4:2:0.

Audio

For audio signals, the compressed recording method is Dolby Digital (AC- 3) with a bit rate of 64-640 kbps and 1 to 5.1 channels. Alternatively, in the linear PCM method with a constant bit rate of 1.5 Mbps for 2 channels, but also worked variable with 1 to 7.1 channels. Sony's PlayStation 3 supports AVCHD additionally DTS.

Data rate

The entire standard is defined up to a bandwidth ( Level 5.1 / H444 profiles) of 960 megabits per second and a resolution of up to four million pixels. The usual data to use rates were the end of 2008 depending on the resolution and compression rate between 5 and 24 megabits per second. This corresponds to a recording length of about 5 (at 24 Megabits per second) to 26 minutes ( at 5 megabits per second) per gigabyte. To use the current highest quality level of 24 megabits per second Class 6 recommended media, which allow a gross data rate of 48 megabits per second.

Specification limit

In early 2010, first Panasonic camcorder offered, the maximum data rate can next for progressive full HD recording at up to 60 frames per second and the requirements of the high volumes of data at 28 megabits per second above and thus set outside the AVCHD specification.

In January 2011, Sony has then presented an appropriate device with the adjustment of up to 28 megabits per second.

When the data rate is beyond the specification of AVCHD, there might be difficulties when playing with any other equipment.

AVCHD 2.0

In early July 2011, the extended standard AVCHD 2.0 was released. The AVCHD format were added up to 1080/60p new specifications for three-dimensional and high -resolution images in the progressive mode. At the same time Trademarks AVCHD 3D, AVCHD and AVCHD Progressive 3D/Progressive were introduced.

Background

AVCHD was created by the Motion Picture Expert Group and implemented by Sony and Panasonic in products because they no longer wanted to rely solely on storage media drives, such as tape drives, hard drives or DVD drives.

Comparison with tape recorder

The magnetic tape is provided the possibility of storing large amounts of data at a comparatively low-cost media. So can be stored on a mini DV tape about 13 gigabytes. By the use of modern storage devices, however, access to the data is not only sequential, but also optional possible. This means the elimination of time-consuming rewinding and direct access to individual scenes, which are usually stored as individual files.

Memory cards were in May 2008 for up to 16 gigabytes are available, but had a significantly higher price than magnetic tapes. Since AVCHD at an identical data rate compared to MPEG -2 ( HD resolution ) achieved significantly greater storage efficiency, the additional costs relativized, ie the cost per time approached as such.

In addition, in the area of ​​consumer video technology was at the same time to AVCHD first recording of full HD content (1920 × 1080 pixels without interpolation) introduced, even if most of 2008 on the market this camcorder resolution still only accessible by interpolation. This also favored the better compressed ( MPEG-2 ) AVCHD format. At the turn of 2009/2010 the market had evolved significantly: There are more and more taking chips used, which supported the full HD format. In addition, ( AVCHDlite for the use of SD ( HC) cards in these mostly) prices for camcorders and video -enabled digital cameras have fallen drastically.

In November 2010, 16 GB-SDHC-S were peicherkarten already be found from 20 €, but even cards available with much higher capacity.

Video editing

AVCHD was used at the beginning mainly for storage on DVD, hard drive or memory card. The intersection of films was provided either in this format, even in MPEG- 2 format. Because now even cheap camcorder with AVC codecs work and have "Full HD " capabilities, video editing in the consumer sector is becoming increasingly important. Due to the strong user demand for this format with low bandwidth with high image resolution and software editing solutions are offered.

The average processing at the Advanced Video Codec High Definition offer several problems described in the following.

Stability

Given that AVCHD is a fairly new codec, many editing programs were also not very stable or slightly flexible even at the beginning.

Computational effort

The high complexity of compression algorithms require a lot of computing time. A powerful (with specification of AVCHD 2006) computer with 3 GHz dual-core processor and 2GB of RAM could not avoid high render times. The computational complexity is heavily dependent on the use of the coding options and how well the rate - distortion optimization has been set. AVC encoder with good performance have about eight to ten times the complexity of an MPEG2 encoder and the decoding is about three times more complex than MPEG -2. The real-time limit ( 30 frames ) for a dual-core processor is with the use of CABAC codec at 10 Mbit / s, with quad-core processor at 15 Mbit / s Without CABAC both systems are in excess of 20 Mbit / s

It is expected new only at the transitions of the source clips, and otherwise maintain the already computed sections.

Due to the high volumes of data and the complexity of the calculations, the manufacturers are increasingly using the computing power of the GPU using CUDA, ATI - Stream, or (rarely ) OpenCL (often at about a quarter to a half of real time).

Some programs also offer the so-called proxy -section, being carried out instead of the AVCHD data with low resolution Spare Clips ( preview), and the actual calculation of high-resolution AVCHD data in the background or is carried out after the end of processing.

The editing software Final Cut Pro from Apple converts AVCHD before editing in a simpler format. The final edit version is then transcoded again into the target format.

Published in early 2011 processors of the Sandy Bridge 2nd generation on the market, which encoding and decoding operations on the H.264 codec (which is the basis of AVC and AVCHD ). Directly support in the processor This sometimes dramatic speed advantages are obtained, which compensate in part the benefits of GPU -based processing in various editing programs again. The high-end processor Intel Core I7 Q2830 QM encoded AVCHD material almost as fast as on a CUDA graphics card of the middle class.

For private use may even be recommended by 1080 pixels to go in this process from the Full HD resolution of 1920 × on the HD resolution of 1280 × down 720 points, because - as confirmed by numerous tests - thus the quality of the later observer hardly decreases, however, the computational effort is greatly reduced. Whether visible or not - - Nevertheless, this reduction in resolution leads to a measurable loss of quality.

3D doubles the computational effort in addition.

Large files

Recording on SD and SDHC cards, as well as many built-in media is carried out almost exclusively in FAT32 or FAT file system. Here there is a maximum file size of 2 GB, which is also in most AVCHD media such as Blu -ray Disc standard. The recording of long scenes then produces more than one file when that file size is exceeded. Many editing programs not thus cope. Camera manufacturers place but usually at a software that can merge into one big file this 2 GB segments, which can then be further processed with common editing software ( for example Sony PMB).

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