AVCHD

From Wikipedia, the free encyclopedia

AVCHD logo

AVCHD (Advanced Video Codec High Definition) is a high-definition recording format for use in digital tapeless camcorders. The format is comparable to other handheld video camera recording formats, particularly TOD, HDV and MiniDV.

Contents

[edit] History

In 2003 Sony introduced XDCAM, one of the first professional tapeless video systems. The format used Professional Disc as recording media. The cost of media was comparable to professional formats that existed at that time, and was prohibitively high for a consumer version of such a camera.

In April 2004 Sony mentioned the possibility of expanding XDCAM format or its variants into consumer market. Rick Clancy, Senior Vice President of Corporate Communications at Sony stated that XDCAM is more of a higher end professional HD product, and future consumer tapeless camcorders would be based on the less expensive Blu-ray format.[1] Similar to Professional Disc, Blu-ray Disc format is based on blue-violet laser technology, but disks are single-sided, do not have protective cartridge, use cheaper media and deliver lower data rates.[2]

In September 2004 Sony augmented Blu-ray Disc specification with AVC and VC-1 video codecs in addition to existing MPEG-2 codec. New codecs provided more efficient compression, meaning longer movies could be stored on the same disc.[3]

In May 2006 Panasonic and Sony announced AVCHD as a format jointly established by the two companies. The original specification was based on existing Blu-ray Disc standard and allowed recording and playback of AVC-encoded video onto 8 cm DVD media instead of Blu-ray media.[4]

In July 2006 the format was amended to include other types of random-access media, like SD/SDHC memory cards, "Memory Stick" cards and hard disk drives.[5]

The first AVCHD camcorder, Sony Handycam HDR-UX1, went on sale in September 2006 and used 8 cm DVD media. Panasonic released its two first AVCHD camcorders in spring 2007, the HDC-DX1 used 8 cm DVD media, the HDC-SD1 became the first AVCHD camcorder to record to SD/SDHC solid-state media. Canon supported the new video format with the HG10 that recorded onto a built-in hard disk drive, and with HR10 that recorded to conventional 8 cm DVD media.

Presently AVCHD has become a viable tapeless consumer high definition video recording format. See full list of products below.

[edit] Overview

File organization on a solid-state AVCHD camcorder
File organization on a solid-state AVCHD camcorder

AVCHD (AVC-HD, AVC HD) employs AVC video codec with inter-frame long GOP compression, and AC-3 or PCM audio codec. A wide range of frame sizes and rates, both interlaced and progressive, is supported. Compared to HDV camcorders based on MPEG-2 codec, AVCHD camcorders achieve higher compression and lower data rates with comparable image quality.

The format supports slide shows, subtitles and menu navigation. Slide shows created out of still AVC pictures can be used for high quality image presentation with or without background audio. Subtitles are used in some camcorders to keep track of recording date/time. DVD-like menu navigation makes AVCHD a more attractive format for consumer users.

Audio, video and subtitle streams are encapsulated into MPEG-2 Transport stream and stored on media as binary files. In this regard AVCHD is similar to TOD.

AVCHD directory structure is derived from the Blu-ray Disc specification but is not identical to it. In particular, known AVCHD implementations use old-fashioned "8.3" filename convention, while Blu-ray disks utilize long filenames. Another notable difference is location of BDMV directory, which contains media files. On a Blu-ray disk and on a DVD-based AVCHD camcorder this directory is placed in the root of recording medium, while on an HDD-based and on a solid-state AVCHD camcorder it is nested two levels below.

Sony claims the format has a total storage time on a MiniDVD of about 20 minutes of high-definition video using "average" bitrates. By comparison, today's 8 cm discs can store 30 minutes of standard-definition MPEG-2 video, and MiniDV tapes can store a full 60 minutes of either standard-definition DV or high-definition (HDV) video. At the maximum resolution, a standard 8 cm DVD will hold just 15 minutes of material. The newer dual layer disks will hold 27 minutes. AVCHD camcorders using hard disks or flash memory such as SD or MemoryStick overcome this constraint and typically offer USB connections to access their content.

AVCHD files when copied to a computer also have the huge benefit of being transferred at the maximum speed of the DVD, SDHC flash card, or hard drive via USB 2.0 connection. That means AVCHD files can realistically be transferred to the computer at speeds from 5 to 30 megabytes per second whereas HDV is forced to transfer at normal video playback speeds of 3.5 megabytes per second using special recording software. Windows XP Windows Movie Maker for example does not support HDV capture and Windows Vista only offers this capability on Premium or Ultimate editions. Windows Movie Maker in Vista supports HDV format but does not permit selective recording and requires users to download the entire tape from the beginning. By contrast, AVCHD files simply need to be copied over using standard file copy/move operations making it far more user friendly.

A significant issue with editing and converting these files is the sheer amount of memory and processing resources required. Decoding and re-encoding AVC is much more resource-intensive than similar processing on MPEG-2, for example. Furthermore, AVCHD employs long-GOP frame storage which, while space-efficient, introduces challenges into editing and decoding of material. However, just as MPEG-2 was originally taxing to home PCs, even needing special PCI decoder cards, it seems likely that AVC's challenges will be overcome with time.

[edit] Compatibility with Blu-ray Disc players

Before AVCHD standard has been finalized, end users could master high definition content in Blu-ray format (BDMV) on either BD-R/BD-RE disks or regular DVD disks. At one point Blu-ray Disc Association was considering separating studio content and home-made content using different folders, namely BDMV for studios and HDMV or BDAV for home use. This idea did not seem to get a lot of traction.[6] Instead, AVCHD is being offered as the means of creating and recording home videos in high definition.

Being creators of AVCHD, Sony and Panasonic generally provide good support for AVCHD disks in their Blu-ray players. In particular, Sony BDP-S1, Panasonic DMP-BD10 (since firmware revision 1.4[7]), Panasonic DMP-BD30[8] and the PlayStation 3 gaming console can play AVCHD video recorded on a regular DVD disk. Playstation 3 can also play AVCHD content from connected USB storage devices. Select Panasonic players and television sets are capable of playing AVCHD content off SDHC memory cards.

On another hand other manufacturers like Samsung do not provide reliable AVCHD support in their products. For example, Samsung removed support for both "BDMV on DVD" and "AVCHD on DVD" in a recent firmware release 2.3 for the Samsung BD-P1200 player.[9]

[edit] Hardware Products

[edit] Sony

  • September 2006: HDR-UX1 (DVD), HDR-UX3/UX5 (DVD), HDR-UX7 (DVD)
  • October 2006: HDR-SR1 (30 GB HDD)
  • June 2007: HDR-SR5 (40 GB HDD), HDR-SR7 (60 GB HDD)
  • July 2007: HDR-SR5C (100 GB HDD), HDR-SR8 (100 GB HDD)
  • Summer 2007: HDR-CX7 (Memory Stick Duo)
  • March 2008: HDR-SR10 (40GB HDD), HDR-SR11 (60 GB HDD, Memory Stick), HDR-SR12 (120 GB HDD, Memory Stick)
  • HDR-TG1/TG3 (Memory Stick)

[edit] Panasonic

  • HDC-SD1 (SDHC)
  • HDC-DX1 (MiniDVD)
  • HDC-SD3 (SDHC, available in Japan only)
  • AG-HSC1U (SDHC, comes with portable 40 GB HDD storage)
  • HDC-SD5, HDC-SD7, HDC-SD9 (all SDHC)
  • HDC-HS9 (60 GB HDD, SDHC)
  • April 2008: AG-HMC70 series (SDHC)

[edit] Canon

  • HR10 (MiniDVD)
  • 2007: HG10 (40 GB HDD)
  • April 2008: HF10, HF100 (SDHC)

[edit] Software

The following video-editing software features support for the AVCHD format:

The following software can convert the AVCHD format to other formats:

  • Roxio's Toast Titanium 9 can import AVCHD clips and burn them into Blu-ray Discs or DVDs, as well as author high-definition content to AVCHD on DVD for playback in a Blu-ray player.
  • Canopus's AVCHD Converter can convert AVCHD clips into a format which can be edited using Canopus' EDIUS 3/4.
  • A related tool, Canopus' ProCoder, can perform conversions that produce files which are usable by other video editing applications that do not support AVCHD natively.
  • Cineform also offers the Neo HDV product that allows AVCHD clips to be converted into I-frame wavelet .avi files designed for editing and post-production. These .avi files can be accepted by many popular consumer non-linear video editors, including those from Sony, Adobe and Corel, which has acquired Ulead.
  • Another useful product is CoreAVC, a reasonably cheap and quick h.264 decoder for Windows, which can decode AVCHD as well as a variety of other h.264 formats.
  • MainConcept sells a codec that is recommended for Adobe Premier users.
  • Nero Vision can convert AVCHD files to other formats such as MPEG-2 or AVI and can import them for use in video editing projects. Nero Vision can also export Sony's M2TS format to MPEG-4 files that can be viewed by Quicktime 7.
  • PowerDVD Ultra comes with an AVCHD codec that can be used with AVISynth and VirtualDubMod as described here.[11]
  • There is a transcoder to convert AVCHD into P2, which is a format you can import into Avid Xpress or AVID Media Composer. The transcoder was created by Main Concept and is distributed free of charge by Panasonic. You can download the file from here.
  • Latest version VAIO Editing Components that pre-loaded with Sony VAIO PCs can serve as a plug-in for Adobe Premiere Pro 2 to support AVC-HD import/export and editing.
  • VoltaicHD is a simple yet useful tool to allow you to convert AVCHD files into other useful formats. The PC version allows output to WMV and AVI but is currently limited to the first 2Gb of any file produced by the camera. A Mac version is also available.

[edit] Specifications

Video
Video signal 1080/60i

1080/50i

1080/24p

 720/60p

720/50p

720/24p

 480/60i 576/50i
Frame size in pixels 1920×1080

1440×1080

 1280 x 720 720×480 720×576
Frame aspect ratio 16:9 4:3, 16:9
Video Compression MPEG-4 AVC/H.264
Luminance sampling frequency 74.25 MHz

55.7 MHz

 74.25 MHz 13.5 MHz 13.5 MHz
Chroma sampling format 4:2:0
Quantization 8 bits (both luminance and chrominance)
Audio
Compression Dolby Digital (AC-3) Linear PCM
Compressed audio bitstream rate 64 to 640 kbit/s 1.5 Mbit/s (2 channels)
Audio mode 1-5.1 channels 1-7.1 channels
System
Stream type MPEG-2 Transport stream
Maximum system data rate ~24 Mbit/s (~18 Mbit/s for DVD)
File extension (generally) mts (on camcorder), m2ts (after import to computer)
Media 8 cm DVD media, SD/SDHC Memory Card, "Memory Stick", Built-in Media

[edit] See also

[edit] References

  1. ^ Sony plans to eventually release Blu-ray HD camcorder.
  2. ^ Blu-ray FAQ.
  3. ^ Sony is developing 200GB Blu-ray storage.
  4. ^ Panasonic and Sony jointly developed new HD Digital video camera recorder format for recording on disc.
  5. ^ Panasonic and Sony expand AVCHD recorder format.
  6. ^ Doom9.com, AVCHD compatibility testing.
  7. ^ DMP-BD10 Firmware Download.
  8. ^ Panasonic Introduces DMP-BD30 Blu-ray Disc player.
  9. ^ Samsung BDP1200 discussion at avsforum.com.
  10. ^ Final Cut Express 4 User Manual (Search for AVCHD)
  11. ^ How to edit AVCHD M2TS files from Sony HDR-SR1 camcorders

[edit] External links