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Betacam
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Betacam is a family of half-inch professional videotape products developed by Sony from 1982 onwards.
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Betacam is a family of half-inch professional videotape products developed by Sony from 1982 onwards. In colloquial use, "Betacam" singly is often used to refer to a Betacam camcorder, a Betacam tape, a Betacam video recorder or the format itself.
All Betacam variants from (plain) Betacam to Betacam SP and Digital Betacam, use the same shape cassettes, meaning vaults and other storage facilities do not have to be changed when upgrading to a new format. The cassettes come in two sizes: S and L. Betacam cameras can only load S tapes, while VTRs can play both S and L tapes. The cassette shell and case for each Betacam cassette is colored differently depending on the format, allowing for easy visual identification. There is also a mechanical key that allows a video tape recorder to tell which format has been inserted.
The format supplanted the three-quarter inch U-Matic format, which Sony had introduced in 1971. In addition to improvements in video quality, the Betacam configuration of an integrated camera/recorder led to its rapid adoption by electronic news gathering organizations.
Even though Betacam remains popular in the field and for archiving, new digital products such as the Multi Access Video Disk Recorder are leading to a phasing out of Betacam products in a studio environment.
Variants
Betacam / Betacam SP
The original Betacam format was launched in August 7, 1982. It is an analog component video format, storing the luminance, "Y", in one track and the chrominance, on another as alternating segments of the R-Y and B-Y components performing Compressed Time Division Multiplex, or CTDM. (Ward 2001, p.30) This splitting of channels allows true broadcast quality recording with 300 lines of horizontal luminance resolution and 120 lines chrominance resolution (versus ~30 for Betamax/VHS), on a relatively inexpensive cassette based format.
The original Betacam format records on cassettes loaded with oxide-formulated tape, which are theoretically the same as used by its consumer market-oriented predecessor Betamax, introduced 7 years earlier by Sony in 1975. A blank Betamax-branded tape will work on a Betacam deck, and a Betacam-branded tape can be used to record in a Betamax deck. However, in later years Sony discouraged this practice, suggesting that the internal tape transport of a domestic Betamax cassette was not well suited to the faster tape transport of Betacam. In particular, the guide rollers tend to be noisy.
Although there is a superficial similarity between Betamax and Betacam in that they use the same tape cassette, they are really quite different formats. Betamax records relatively low resolution composite video using a heterodyne color recording system and only two recording heads, while Betacam uses four heads to record in component format, at a much higher linear tape speed, resulting in much higher video and audio quality. A typical L-750 length Betamax cassette that yielded about 3 hours of recording time on a Betamax VCR at its B-II speed, only provided 30 minutes record time on a Betacam VCR or camcorder.
It may also be noted that Matsushita / Panasonic also introduced a professional 1/2" component videotape format which used VHS style tape cassettes called "M-Format". However, while Sony's Betacam system rapidly became an industry standard, M format was a marketing failure. A followup format called M-II—basically the M version of Betacam SP—was a great improvement, but still failed to make much headway in the marketplace, although it was used as an internal standard at NBC for a time. Although technically M-II was in some ways an improvement over Betacam SP, Betacam SP had the overwhelming advantage of a high degree of compatibility with the existing (and very large) Betacam infrastructure.
Betacam was initially introduced as a camera line along with a video cassette player. The first cameras were the BVP-3, which utilized 3 saticon tubes, and the BVP1, which used a single tri-stripe Trinicon tube. Both these cameras could be operated standalone, or with their docking companion VTR, the BVV-1, (quickly superseded by the BVV-1A) to form the BVW-1 (BVW-1A) integrated camcorder. Tapes could not be played back in camera except in black and white for viewing in the camera's viewfinder only. Color playback required the studio source deck at first, the BVW-10, which could not record, only play back. It was primarily designed as a feeder deck for A/B roll edit systems, usually for editing to a 1" Type C or 3/4" U-matic cassette edit master tape. There was also the BVW-20 field playback deck, which was a portable unit with DC power and a handle, that was used to verify color playback of tapes in the field. Unlike the BVW-10, it did not have a built in Time Base Corrector, or TBC.
With the popular success of the Betacam system as a news acquisition format, the line was soon extended to include the BVW-15 studio player, and the BVW-40 Studio Edit Recorder. The BVW-15 added Dynamic Tracking which enabled clear still frame and jog playback, something the BVW-10 could not deliver. The BVW-40 enabled for the first time editing to a Betacam master, and if setup and wired correctly, true component video editing. It was also possible to do machine to machine editing between a BVW-10/15 and BVW-40 without an edit controller—a single serial cable between the units was all that was required to control the player from the recorder in performing simple assemble and insert editing. Additionally there were two field models introduced, the field recorder BVW-25, and the BVW-21 play only portable field deck.
At its introduction, many insisted that Betacam remained inferior to the bulkier 1" Type C and B recording, the standard broadcast production format of the late 70s to mid 80s. Additionally, the maximum record time for both the cameras and studio recorders was only half an hour, a severe limitation in television production. There was also the limitation that high quality recording was only possible if the original component signals were available, as they would be in a cp. If they had already been converted to composite video, re-converting them to components for recording and then eventually back to composite for broadcast, caused a severe drop in quality.
In 1986, Betacam SP was developed, which increased horizontal resolution to 340 lines. While the quality improvement of the format itself was minor, the improvement to the VTRs was enormous, in quality, features, and particularly, the new larger cassette with 90 minutes of recording time. Beta SP (for "Superior Performance") became the industry standard for most TV stations and high-end production houses until the late 1990s. Despite the format's age Beta SP remains a common standard for video post-production. The recording time is the same as for Betacam, 30 and 90 minutes for S and L, respectively. Tape speed is slightly slower in machines working in the 625/50 format, increasing tape duration of one minute for every five minutes of run time. So, a 90 minute tape will record 108 minutes of video in PAL.
Betacam SP is able to achieve its namesake "Superior Performance" over Betacam in the fact that it uses metal-formulated tape, as opposed to Betacam's oxide tape. Sony designed Betacam SP to be partially forward compatible with standard Betacam, with the capability that Betacam SP tapes recorded on Betacam SP decks can be played in oxide-era Betacam VTRs (such as the BVW-15 and BVW-40 mentioned earlier), but for playback only. Betacam SP-branded tapes cannot be used for recording in consumer Betamax VCRs like oxide Betacam tapes, due to Betacam SP's metal-formulation tape causing the video heads in a Betamax deck to wear prematurely, which are made of a softer material than the heads in a standard Betacam deck. However, Betacam SP tapes can be used without a problem in ED Beta VCRs, since the ED Beta format uses metal-formulated tape as well.
The new Betacam SP studio decks were the players, the BVW-60 and BVW-65, with Dynamic Tracking and the Edit Recorders, the BVW-70, and the Dynamic Tracking model, the BVW-75. The BVV-5 was the BetcamSP dockable camera back, which could play back in color if its companion playback adapter was used. A new SP field recorder, the BVW-35, possessed the added benefit of a standard RS422 serial control port that enabled it to be used as an edit feeder deck. Though the four new studio decks could utilize the full 90-minute Betacam SP cassettes, the BVW-35 remained limited to the original Beta form factor 30-minute cassette shells. Answering a need for a basic office player, Sony also introduced the BVW-22, a much less expensive desktop model that could be used for viewing and logging 90-minute cassettes, but could not be configured into an edit system.
Sony followed up the SP Field Recorder with the BVW-50, that could record and play the large size 90 minute cassettes. After this, the deck line was relatively stagnant and incredibly popular for a decade, aside from some specialty models that could record digital audio.
Until the introduction of the BVW-200 camera though, the camera and recorder configuration was a docking system. The BVW-200 was an integrated camera recorder system. It sacrificed the flexibility of a docking camera in order to lose a substantial amount of weight. Eventually, non-docking camcorders became the most popular design by the mid-90s.
The final analog Betacam SP camcorder was the BVW-600, which paired a camera front section very similar to the one on the DigiBeta DVW-700 to a BetaSP recorder. Like every other Betacam camera system, and unlike the DigiBeta DVW-700, the camera could not play back in color without the use of an outboard adapter.
In the early 1990s a "pro" or "industrial" line of decks was introduced, with model numbers that echoed the naming conventions of Sony's 1970s era U-matic editing decks. These were the PVW-2600 edit source feeder and the PVW-2800 edit recorder. These high quality machines primarily lacked the third and fourth audio channels of the BVW series. In the mid-nineties, the far less expensive UVW series debuted. These machines were considerably simpler, somewhat lower quality, and were designed primarily to be used as companions to computer systems, and possessed very limited front panel controls, no jog and shuttle; and with Time Base Corrector (TBC) control available only with an optional remote TBC controller. These were represented by the UVW-1800, a very popular edit recorder, and the UVW-1200, UVW-1400 and UVW-1600 players.
Betacam and Betacam SP tape cassette shells varied in color depending on the manufacturer. Many companies sold Betacam tapes, sometimes of their own manufacture, sometimes re-branded. Fuji, Maxell, Ampex and 3M were just some of the major brands to do so.
Ampex, Thomson SA and Philips each sold rebranded OEM versions of some of the Sony VTRs and Camcorders at various times in the 1980s and 1990s. Other than nameplates, these models were identical to the Sony models.
Digital Betacam
Digital Betacam (commonly referred to as Digibeta, d-beta, dbc or simply Digi) was launched in 1993. It supersedes both Betacam and Betacam SP, while costing significantly less than the D1 format. S tapes are available with up to 40 minutes running time, and L tapes with up to 124 minutes.
The Digital Betacam format records a DCT-compressed component video signal at 10-bit YUV 4:2:2 sampling in NTSC (720×486) or PAL (720×576) resolutions at a bitrate of 90 Mbit/s plus four channels of uncompressed 48 kHz / 20 bit PCM-encoded audio. A fifth analog audio track is available for cueing, and a linear timecode track is also used on the tape. It is a popular digital video cassette format for broadcast use. Its main competitor is the Panasonic DVCPRO50 cassette format.
Another key element which aided adoption was Sony's implementation of the SDI coaxial digital connection on Digital Betacam decks. Facilities could begin using digital signals on their existing coaxial wiring without having to commit to an expensive re-installation.
Sony branded Digital Betacam videotape is sold in a blue-grey cassette container.
Betacam SX
Betacam SX is a digital version of Betacam SP introduced in 1996, positioned as a cheaper alternative to Digital Betacam. It stores video using MPEG 4:2:2 Profile@ML compression, along with four channels of 48 kHz 16 bit PCM audio. All Betacam SX equipment is compatible with Betacam SP tapes. S tapes have a recording time up to 62 minutes, and L tapes up to 194 minutes.
The Betacam SX system was very successful with newsgathering operations which had a legacy of Betacam and Betacam SP tapes. Some Betacam SX decks, such as the DNW-A75 or DNW-A50, can natively play and work from the analog tapes interchangeably, because it contains both analog and digital playback heads.
Betacam SX uses MPEG-2 4:2:2P@ML compression, in comparison with other similar systems that use 4:1:1 or 4:2:0 coding. It gives better chroma resolution and allows certain postproduction processes such as Chroma-key.
This format compresses the video signal from approximately 180Mb/s to only 18Mb/s. This means a compression ratio of around 10:1, which is achieved by the use of mild temporal compression, where alternate frames are stored as MPEG I-frames and B-frames, giving rise to an IBIB sequence on tape.
Together with Betacam SX, Sony introduced a generation of hybrid recorder, allowing use of both tape and disk recording on the same deck, and high speed dubbing from one to another. This was intended to save wear on the video heads for studio applications, as well to speed up online editing.
Betacam SX also features a good shot mark feature, that allows marking of each scene for fast scanning of the tape, looking at recorded marks on each single cassette, and showing the markers to the operator.
The cameras themselves are generally considered by most sound recordists to be quite noisy in operation, possibly because the amount of computer processing power, and subsequent generated heat, leads to cooling fans being used to keep the camera at a reasonable temperature.
Betacam SX tape shells are bright yellow.
Although Betacam SX machines have gone out of production, the format is still used by many newsgathering operations, including CNN, Canada's CBC and CTV, San Diego's KFMB-TV and NBC's operations in the San Francisco Bay Area at KNTV and KSTS. Many news archives still contain SX tapes.
MPEG IMX
MPEG IMX is a 2001 development of the Digital Betacam format. It uses the MPEG compression system, but at a higher bitrate than Betacam SX. The IMX format allows for a CCIR 601 compliant video signal, with eight channels of audio and timecode track. It lacks an analog audio (cue) track as the Digital Betacam, but will read it as channel 7 if used for playback.
Compression is applied in three different formats: 30 (6:1 compression), 40 (4:1 compression) or 50 Mbit/s (3.3:1 compression) which allows different quality/storage efficiency ratios. Video is recorded at MPEG-2 4:2:2 Profile @ ML.
With its new IMX VTRs, Sony introduced some new technologies including SDTI and e-VTR. SDTI allows for audio, video, timecode, and remote control functions to be transported by a single coaxial cable, while e-VTR technology extends this by allowing the same data to be transported over IP by way of an ethernet interface on the VTR itself.
All IMX VTRs can natively playback Betacam SX tapes, and some, such as the MSW-M2000P/1 are capable of playing back Digital Betacam cassettes as well as analog Betacam and Betacam SP cassettes, but they can only record to their native IMX cassettes. S tapes are available with up to 60 minutes capacity, and L tapes hold up to 184 minutes. These values are for 525/60 decks, but will extend in 625/50. A 184 minute tape will record for, as the label itself specifies, 220 minutes.
IMX machines feature the same good shot mark function of the Betacam SX.
MPEG IMX cassettes are a muted green, however, the new XDCAM format allows recording of MPEG IMX on a tapeless format, Professional Disc.
HDCAM / HDCAM SR
HDCAM, introduced in 1997, is an HD version of Digital Betacam, using an 8-bit DCT compressed 3:1:1 recording, in 1080i-compatible downsampled resolution of 1440×1080, and adding 24p and 23.976 PsF modes to later models. The HDCAM codec uses non-square pixels and as such the recorded 1440×1080 content is upsampled to 1920×1080 on playback. The recorded video bitrate is 144 Mbit/s. Audio is also similar, with four channels of AES/EBU 20-bit/48 kHz digital audio.
It is used for Sony's cinematic CineAlta range of products.
HDCAM SR, introduced in 2003, uses a higher particle density tape and is capable of recording in 10 bits 4:2:2 or 4:4:4 RGB with a bitrate of 440 Mbit/s. The "SR" stands for "Superior Resolution". The increased bitrate (over HDCAM) allows HDCAM SR to capture much more of the full bandwidth of the HDSDI signal (1920×1080). Some HDCAM SR VTRs can also use a 2× mode with an even higher bitrate of 880 Mbit/s, allowing for a 4:4:4 stream at a lower compression. HDCAM SR uses the new MPEG-4 Part 2 Studio Profile for compression, and expands the number of audio channels up to 12 at 48 kHz/24 bit.
HDCAM SR is used commonly for HDTV television production. As of 2007, many prime-time network television shows use HDCAM SR as a master recording medium.
Some HDCAM VTRs play back older Betacam variants, for example, the Sony SRW-5500 HDCAM SR recorder, plays back and records HDCAM and HDCAM SR tapes and with optional hardware also plays and upconverts Digital Betacam tapes to HD format. Tape lengths are the same as for Digital Betacam, up to 40 minutes for S and 124 minutes for L tapes. In 24p mode the runtime increases to 50 and 155 minutes, respectively.
HDCAM tapes are black with an orange lid, and HDCAM SR tapes black with a cyan lid.
440 Mbit/s mode is known as SQ, and 880 Mbit/s mode is known as HQ, and this mode has recently become available in studio models (e.g. SRW-5800) as well as portable models previously available.
See also
External links
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