Hi8
To counter the introduction of the Super-VHS format, Sony introduced Video Hi8 (short for high-band Video8.) Like SVHS, Hi8 used improved recorder electronics and media-formulation to increase picture detail. In both systems, a higher-grade videotape and recording-heads allowed the placement of the luminance-carrier at a higher frequency, thereby increasing luminance bandwidth. Both Hi8 and SVHS were officially rated at a luminance resolution of 420 horizontal TV/lines (560x480 in today's digital terms), a vast improvement from their respective base-formats of 240 lines and roughly equal to laserdisc quality. Chroma resolution for both remained unchanged at approximately 30 lines horizontal. All Hi8 equipment supported recording and playback of both Hi8 and legacy Video8 recordings. Video8 equipment cannot play Hi8 recordings.
Both S-VHS and Hi8 retained the audio recording systems of their base formats; VHS HiFi Stereo outperformed Video8/Hi8 AFM, but remained restricted to high-end machines.
In the late 1980s, digital (PCM) audio was introduced into some higher grade models of Hi8 (but never SVHS) recorders. Hi8 PCM audio operated at a sampling rate of 32 kHz with 8-bit samples -- far higher quality then the monoaural linear dubbing offered by S-VHS and VHS VCRs. PCM-capable Hi8 recorders could simultaneously record PCM stereo in addition to the legacy (analog AFM) stereo audiotracks.
The final upgrade to the Video8 format came in 1998, when Sony introduced XR capability (extended resolution). Video8-XR and Hi8-XR offered a modest 10% improvement in luminance detail, while retaining full backward compatibility with older non-XR equipment. XR recordings were fully playable on older non-XR equipment, though without the benefits of XR.
PCM Multi Audio
The Sony EV-S900 (Hi8), Sony EV-S700U and Pioneer VE-D77 (Video8) all supported a mode called "PCM Multi Audio Recording". While other 8mm decks supported stereo PCM recording, these units provided five additional stereo PCM tracks that were recorded in the video area of the signal. This allowed 8mm tapes to hold 6 "parallel" tracks of audio, each up to 4 hours long in LP mode. Only one stereo track could be recorded or listened to at a time, and tracks were selected with the "PCM Multi Audio" selector button.
Digital8
Introduced in 1999, Digital8 is digital video recorded on Hi8 media using the industry standard DV codec. In engineering terms, Digital8 and miniDV are indistinguishable at the logical format level. Digital8 uses the same cassettes as Video8, but otherwise bears no resemblance to the Video8 analog video system. Some Digital8 equipment can play (not record) Hi8/Video8 recordings, but this is not a standard feature of Digital8 technology. To store the digitally-encoded audio/video on a standard NTSC Video8 cassette, the tape must be run at double the Hi8 speed. Thus a 120 minute NTSC Hi8 tape yields 60 minutes of Digital8 video. Most Digital8 units offer an 'LP' mode, which increases recording time on an NTSC T-120 tape to 90 minutes.
For PAL, the Digital8 recorder runs one-and-a-half times faster, thus a 90-minute PAL Hi8 tape yields 60 minutes of Digital8 video. PAL LP mode returns the tape speed to the Hi8 SP speed, so a Hi8 90 minute tape yields 90 minutes of Digital8 video.
Sony has licensed Digital8 technology to at least 1 other firm (Hitachi) who marketed a few models for a while, but presently, only Sony sells Digital8 consumer equipment. Digital8's main rival is the consumer miniDV format, which uses narrower tape and a correspondingly smaller cassette shell. Since both technologies share the same logical audio/video format, Digital8 can theoretically equal miniDV or even DVCAM in A/V performance. But as of 2005, Digital8 has been relegated to the entry-level camcorder market, where price and not performance is the driving factor. Meanwhile, miniDV is the de facto standard of the domestic digital tape camcorder market.