AVCHD (Advanced Video Coding High Definition)Panasonic drivers brochure panasonic.com is a file-based format for the digital recording and playback of high-definition video. It is H.264 and Dolby AC-3 packaged into the MPEG transport stream, with a set of constraints designed around camcorders.
Developed jointly by Sony and Panasonic, the format was introduced in 2006 primarily for use in high definition consumer camcorders. Related specifications include the professional variants AVCCAM and NXCAM.
Favorable comparisons of AVCHD against HDV and XDCAM EX solidified perception of AVCHD as a format acceptable for professional use. Both Panasonic and Sony released the first consumer AVCHD camcorders in spring of 2007.Release dates based on the oldest reviews available, all of which suggest that the models had just been released. Panasonic released the first AVCHD camcorder aimed at the professional market in 2008, though it was nothing more than the (by then discontinued) FLASH card consumer model rebadged with a different model number.
In 2011 the AVCHD specification was amended to include 1080-line 50-frame/s and 60-frame/s modes (AVCHD Progressive) and stereoscopic video (AVCHD 3D). The new video modes require double the data rate of previous modes.
AVCHD and its logo are trademarks of Sony and Panasonic.
Overview
For video compression, AVCHD uses the H.264/MPEG-4 AVC standard, supporting a variety of standard, high definition, and stereoscopic (3D) video resolutions. For audio compression, it supports both Dolby AC-3 (Dolby Digital) and uncompressed linear PCM audio. Stereo and multichannel surround (5.1) are both supported.
Aside from recorded audio and video, AVCHD includes many user-friendly features to improve media presentation: menu navigation, simple slide shows and subtitles. The menu navigation system is similar to DVD-Video, allowing access to individual videos from a common intro screen. Slide shows are prepared from a sequence of AVC still frames, and can be accompanied by a background audio track. Subtitles are used in some camcorders to timestamp the recordings.
Audio, video, subtitle, and ancillary streams are multiplexed into an MPEG transport stream and stored on media as binary files. Usually, memory cards and HDDs use the FAT file system, while optical discs employ UDF or ISO 9660.
At the file system level, the structure of AVCHD is derived from the Blu-ray Disc specification, but is not identical to it. In particular, it uses legacy "8.3" file naming convention, while Blu-ray Discs utilize long filenames (this may be caused by the fact that FAT implementations utilizing long file names are patented by Microsoft and are licensed on a per unit sold basis). Another difference is location of the BDMV directory, which contains media files. On a DVD-based camcorder the BDMV directory is placed at the root level, as on the Blu-ray Disc. On the HDD-based Canon HG10 camcorder the BDMV directory is located in the AVCHD directory, which is placed at the root level. Solid-state Panasonic and Canon camcorders nest the AVCHD directory inside the PRIVATE directory. Following a standard agreed upon by many still camera manufacturers, solid-state camcorders have a root-level DCIM directory for still images.
AVCHD is compatible with the Blu-ray format and can be authored without re-encoding on Blu-rays or DVDs, though not all Blu-ray Disc players are compatible with AVCHD video authored on DVD media, a format known as AVCHD disc.
AVCHD recordings can be transferred to a computer by connecting the camcorder via the USB connection. Removable media like SDHC and Memory Stick cards or DVDs can be read on a computer directly. Copying files from an AVCHD camcorder or from removable media can be performed faster than from a tape-based camcorder, because the transfer speed is not limited by realtime playback.
Just as editing DVCPRO HD and HDV video once demanded an expensive high-end computer, AVCHD editing software requires powerful machines. Compared to HDV, AVCHD requires 2-4 times the processing power for realtime playback, placing a greater burden on the computer's CPU and graphics card. Improvements in multi-core computing and graphics processor acceleration bring AVCHD playback to mainstream desktops and laptops.
Video formats
AVCHD supports a variety of video resolutions and scanning methods, which was further extended with the 2011 amendment of the specification. The licensing body of the specification defines a variety of labels for products compliant with specific features.
Most AVCHD camcorders support only a handful of the video and audio formats allowed in the AVCHD standard.
Interlaced video AVCHD supports both standard definition (AVCHD-SD) and high definition (AVCHD 1080i) interlaced video. AVCHD 1080i is available on most AVCHD camcorders. For some models this is the only recording mode offered.
AVCHD-SD is used in the shoulder-mount Panasonic HDC-MDH1, as well as on its North American AG-AC7 cousin. A successor model the AG-AC8, is also capable of recording in AVCHD-SD mode. Several models from JVC like the consumer camcorders GZ-HM650, GZ-HM670 and GZ-HM690 as well as the professional camcorder JVC GY-HM70 can record AVCHD-SD video. AVCHD-SD is not compatible with consumer DVD players, because it employs AVC video encoding instead of MPEG-2 Part 2. AVCHD-SD can be played on a Blu-ray Disc player without re-encoding.
Interlaced video had been originally designed for watching on a cathode-ray tube television set. Material recorded for interlaced presentation may exhibit combing or ghosting when it is rescaled, filmed out or watched on a computer or another progressive-scan device without proper deinterlacing.
Some AVCHD 1080i camcorders can capture progressive video and record it within interlaced stream borrowing techniques from television industry. In particular, Progressive segmented frame (PsF) is utilized in some Panasonic (25p Digital Cinema), Canon (PF25, PF30) and Sony camcorders. The 2:3 pulldown technique is used in some 60 Hz versions of Canon (PF24) and Panasonic (24p Digital Cinema) camcorders for recording 24-frame/s progressive video. Most editing tools treat progressive video recorded within an interlaced stream as interlaced, though some editing systems and most standalone Blu-ray Disc players are capable of recognizing the pulldown pattern to recover the original frames using the process known as inverse telecine.
Progressive-scan video
Since the very beginning, the AVCHD specification had supported 720-line progressive recording mode at frame rates of 24 and 60 frames/s for 60 Hz models and 50 frames/s for 50 Hz models. Frame rates of 25 frames/s and 30 frames/s are not directly available in 720p mode, but can be simulated with frame repeating, when every frame is either repeated twice or a special flag in the video stream instructs a decoder to play every frame twice to adhere to output rate of 50 or 60 frames/s.
Many of the digital compact cameras made by Panasonic, such as the DMC-ZS3/DMC-TZ7, DMC-FT1, DMC-FZ35/DMC-FZ38, and DMC-ZS-7/TZ-10 offer 720p video recording with effective frame rate of 25 or 30 frames/s in a format called AVCHD Lite (see below).
Until the advent of AVCHD Progressive mode, native progressive-scan video for 1080-line resolution had been available only in 24 frames/s variant. In 2010, Panasonic introduced a new lineup of consumer AVCHD camcorders with 1080-line 50p/60p progressive-scan mode (frame rate depending on region). Panasonic advised that not all players that support AVCHD playback could play 1080-line 50p/60p video. In 2011, this mode was officially included into the AVCHD specification as part of 2.0 addendum, and has been called AVCHD Progressive. This mode uses the same AVCHD folder structure and container files for storing video, with the maximum bit rate of 28 Mbit/s. In 2011, Sony introduced consumer and professional AVCHD models capable of AVCHD Progressive recording. In 2012 JVC announced the GY-HMQ10 model, which also can record AVCHD Progressive video.
Audio formats
Most AVCHD camcorders record audio using Dolby Digital (AC-3) compression scheme. Stereo and multichannel audio is supported. Audio data rate can range from 64 kbit/s to 640 kbit/s. In practice, data rates of 256 kbit/s and 384 kbit/s have been observed.
Some professional models allow recording uncompressed linear PCM audio.
Media
AVCHD specification allows using recordable DVDs, memory cards, non-removable solid-state memory and hard disk drives as recording media.
DVD
When the AVCHD standard was first announced, recordable DVD was the only recording medium. To reduce camcorder size, manufacturers opted for an 8 cm disc, sometimes called miniDVD. Recording capacity of an 8 cm disc ranges from 1.4 GB for a single-sided single layer disc to 5.2 GB for a double-sided double layer disc.
Pros: DVDs are familiar to most consumers, thus considered user-friendly. Recordable DVDs are relatively cheap. Recorded disc can be played back in most Blu-ray Disc players. Discs can be used for long-term storage of recorded video.
Cons: Some argue that the longevity of recordable DVDs may be shorter than expected. Rewritable DVDs cost more than write-once discs. DVDs must be "finalized" to play back on set-top players (though DVD-RWs can be unfinalized again). Double-layer recording is less robust than single-layer recording. To use both sides of a double-sided disc it must be flipped over, because camcorders have pickup from one side only. AVCHD DVDs can only be played back on DVD/Blu-ray players specifically designed to do so. The AVCHD specification limits data rate for DVD-based AVCHD camcorders to 18 Mbit/s, but no DVD-based AVCHD camcorder manufactured to date is capable of recording at data rate higher than 12 Mbit/s (Canon, Sony) or 13 Mbit/s (Panasonic). A single-sided single-layer 8 cm DVD can fit only 15 minutes of video at 12 Mbit/s, 14 minutes at 13 Mbit/s. DVD pickup mechanism is very susceptible to vibration. 8 cm DVDs cannot be used in many slot-loading drives and may even damage the drive.
As the capacity of memory cards grew and their price dropped, DVDs use for recordable media declined. No DVD-based AVCHD camcorders have been produced since 2008. While DVDs are no longer used for acquisition, they remain popular as distribution media. Many authoring programs offer "AVCHD" profile for recording high definition video on a DVD. Such AVCHD discs are incompatible with regular DVD-Video players, but play in many Blu-ray Disc players. A conventional single-layer 12 cm DVD can store 35 minutes of video recorded at the maximum bit rate the AVCHD specification allows for DVD media—18 Mbit/s.
Hard disk drive
A hard disk drive was added as an optional recording medium to AVCHD specification shortly after the new video standard had been announced. Presently, capacity of built-in HDDs ranges from 30 GB to 240 GB.
Pros: Higher capacity than other media types, which allows for longer continuous recording.
Cons: Sensitive to atmospheric pressure. The HDD may fail if the camcorder is used at altitudes above . Vulnerable to mechanical shock or fast movement. All HDD-based AVCHD camcorders employ non-removable disks. To transfer video to a computer the camcorder must be connected with a USB cable. Most camcorders require using an AC power adapter for this operation. The sound of moving magnetic heads may be heard in the recorded video when recording in quiet environment. Replacing a damaged HDD requires disassembling a camcorder and cannot be done by a consumer.
Solid-state memory card
Many AVCHD camcorders employ Secure Digital or "Memory Stick" memory cards as removable recording media. Solid-state memory cards offer rewritable storage in a compact form factor with no moving parts.