The ATTO Express A/V Control Panel requires an ATTO SiliconExpress II/3D/IV/4D FAST SCSI-2 accelerator. This Control Panel is only certified on Quadra and PowerPC series Macintoshes.
The ATTO SiliconExpress family of accelerators were designed to burst large amounts of data in a short time interval over the NuBus. Desktop video hardware solutions, such as the Radius VideoVision Studio and Data Translation Media 100, require the NuBus to be available at regular specific intervals so they also may transfer large amounts of NuBus data. The combination of two high-performance products requires some cooperation. The Express A/V Control Panel accomplishes this task perfectly. The TrueVision Targa 2000 system is now also supported by the A/V Control Panel (ver 2.2 and above).
NO DROPPED FRAMES!!!!
The standard Macintosh SCSI port allows "no dropped frames", but only at a very low image quality. The SiliconExpress family of accelerators allows you to greatly increase the image quality without the normal penalty of dropped frames.
HIGHER DATA RATES = LOWER COMPRESSION = HIGHER IMAGE QUALITY
HOW TO USE THE ATTO EXPRESS A/V CONTROL PANEL
The ATTO Express A/V Control Panel has three groups of radio buttons.
The first option is to enable/disable the A/V DSP Manager. This option is to correct an apparent bug in the Macintosh 660AV/840AV DSP hardware. The symptom of this bug is a system hang when playing QuickTime footage (if the footage includes sound). When this symptom is observed, enable the A/V DSP option for complete compatiblity. For maximum performance during recording, turn option off until you are ready for playback. This is a real-time selection, therefore, reboots are not necessary after changing the setting. We have also discovered a related problem when using Adobe Photoshop 2.5.1 and the Adobe DSP plug-in. This Adobe DSP hang is also corrected by enabling the A/V DSP Manager. This option is totally irrelevant on the PowerPC - on or off equals a nop (no operation). Do not turn on this option on other non-A/V 680x0 Macs. Not only is it unnecessary, it will slightly decrease overall system performance.
The second option is to enable/disable the RealTime NuBus Manager. This option controls the interaction between the SiliconExpress cards and the Radius VideoVision Studio product. This option may include other video capture products in the future. Different proprietary Bus Management algorithms are used based on the model Macintosh you are using. This option should be enabled when using Radius' VideoVision Studio, but it is not needed for other applications. Although this option will turn on Bus Management with the Targa 2000, it is not a recommended solution. The A/V Control Panel uses a slightly different algorithm for the Targa 2000. This will be discussed later in this readme file.
The third option is to select a level of NuBus Traffic Spacing. This option is only available for systems using the SiliconExpress IV or 4D. If you have a SiliconExpress II or 3D, you will not see this option on your A/V Control Panel. The best way to understand this option is to think of an on-ramp to a busy highway. Imagine the heavy traffic as being the NuBus traffic from the SiliconExpress IV/4D, and the on-ramp traffic as being another NuBus Controller wanting to get on. If you are trying to quickly get on the highway, you look for that little space that you can squeeze into. If you do not get a space, you sit there and wait for one to open up. This is unacceptable for real-time applications such as Digital Video. If a Digital Video Board can not get on the NuBus at the instant it requests it, the real-time characteristic is lost. This usually shows itself as dropped frames or poor quality audio. Therefore, to better balance your system, you may optionally add a level of NuBus gapping. This does have the effect of slightly decreasing the SiliconExpress bandwidth, but this is exactly what it means to balance a system. This option works best on older Quadras such as Q700/Q950 that were known to have a slower NuBus. You should find that newer Quadras and all PowerPC's will perform better with NuBus Traffic Spacing set to "NONE".
TARGA 2000
The Targa 2000 takes advantage of NuBus-to-NuBus transfers - a seldom used feature of the SiliconExpress. The SiliconExpress is a BusMaster, therefore, it can control the NuBus without any assistance from the NuBus controller on the Macintosh motherboard.
NuBus-to-NuBus: No significant interaction from the slower motherboard-based NuBus Controller.
Recording - Video and Audio is captured/compressed by the Targa 2000 and stored in its onboard memory. This data is then transferred directly to the SiliconExpress (the SiliconExpress BusMaster is in total control of this 64 byte blockmode transfer).
Playback - SCSI Data is transferred directly to the Targa 2000's onboard memory. As in record mode, the SiliconExpress controls the 64 byte blockmode transfer. The Targa 2000 uncompresses this data to recreate the audio/video information.
It is three to four times faster for the SiliconExpress to transfer "Blockmode" data directly to the Targa 2000, than it is for the SiliconExpress to transfer "Blockmode" data to the motherboard, and then the motherboard to retransfer "non-Blockmode" data to the Targa 2000.
By default, we do not allow NuBus-to-NuBus transfers. If the A/V Control Panel is installed and it recognizes a Targa 2000, the feature will be turned on for that particular NuBus slot.
