OSSC Pro
Contents
Introduction
OSSC Pro is an advanced low-latency video digitizer, scan converter and scaler designed primarily for connecting retro video game consoles and home computers to modern displays.
If you're new to the OSSC and scalers/processors in general, you may wish to jump to the quick start guide.
Features
- Detection and digitization of various analog SDTV/EDTV/HDTV/PC modes
- Up to ~165MHz sampling clock for both analog and digital video sources, supporting high resolutions like 1080p@60
- Various sampling presets for classic consoles and home computers
- Ultra low latency line multiplication for 240p, 480i, 288p, 576i, 384p, 480p, 576p and 720p sources
- Full-fledged scaler mode with configurable polyphase scaling filter
- Framelocked and free-running scaler modes to select between judder-free or interrupt-free operation
- Deinterlacer supporting motion adaptive, weave and bob algorithms for 480i, 576i, 960i, and 1080i
- All video processing done in RGB domain (8bpc) - no internal conversion to subsampled YCbCr
- Video and sync LPF for less-than optimal input signals
- Various AV input options, both analog and digital (see table below)
- Full-range 24-bit RGB output through DVI/HDMI
- Output from 240p to 2560x1440@60Hz (or to 2880x2160@60Hz with 2x pixel repetition)
- 100Hz and 120Hz output options
- (HD-)CRT output modes including 1920x540 and 1080i
- Expansion card support with 36 GPIOs
- Emulated scanlines with fully configurable strength and interval
- Postprocessing options including masks and BFI
- Character OLED display
- IR control using dedicated remote control, OSSC L336 remote or any other remote supporting NEX IR protocol
- Button & mini-joystick for basic control without remote
- Micro-SD card socket for FW updates and additional profile storage
- USB port (FS) for future expandability
Board versions and availability
Production board
Pre-assembled boards are sold worldwide by:
| VideoGamePerfection.com |
|---|
|
| List of components (v1.5) |
More information & discussion
- Original forum thread
- Dedicated discussion forums
- Quick Start Guide (PDF)
AV inputs
Input is selected via remote key / OSD input menu. The table below summarizes available inputs and their corresponding remote hotkeys.
AV1 (SCART)
The SCART connector of OSSC Pro supports a number of video/sync formats. SCART-RGB sources can be connected as-is while other formats require passthru cables/adapters.
| Input name | Remote hotkey | Notes |
|---|---|---|
| AV1_RGBS | 1 | For video level c-sync only. Sync can be also extracted from composite video / luma. |
| AV1_RGsB | 4 | Use suitable adapter / SCART cable. |
| AV1_YPbPr | 4 (tap twice) | Use YPbPr to SCART passthru adapter. Some suitable adapters are sold online (e.g. this) but most don't include audio jacks. |
| AV1_RGBHV | 7 | Needs a custom adapter/cable which routes HSYNC to SCART pin 12 and VSYNC to pin 10. |
| AV1_RGBCS | 7 (tap twice) | For TTL c-sync only. Needs a custom adapter/cable which routes CSYNC to SCART pin 12. |
AV2 (5xRCA)
The 5xRCA connector set of OSSC Pro supports RGsB or YPbPr sources.
| Input name | Remote hotkey | Notes |
|---|---|---|
| AV2_YPbPr | 2 | Use YPbPr to SCART passthru adapter. Some suitable adapters are sold online (e.g. this) but most don't include audio jacks. |
| AV2_RGsB | 2 (tap twice) | Use suitable adapter / SCART cable. |
AV3 (HD-15 "VGA" + 3.5mm jack)
The HD-15 connector allows connecting e.g. a classic PC or Dreamcast to OSSC Pro.
| Input name | Remote hotkey | Notes |
|---|---|---|
| AV3_RGBHV | 3 | Normal VGA pinout |
| AV3_RGBCS | 3 (tap twice) | For TTL c-sync only (connected to hsync pin) |
| AV3_RGBS | 6 | For video level c-sync only. Sync is connected to HD-15 pin 4 via a custom adapter / cable. |
| AV3_RGsB | 9 | Use suitable adapter / cable. |
| AV3_YPbPr | 9 (tap twice) | Use suitable adapter / cable. |
AV4 (HDMI)
The HDMI connector allows connecting digital AV sources to OSSC Pro. HDCP is not supported.
| Input name | Remote hotkey | Notes |
|---|---|---|
| AV4 | 5 |
Toslink
The toslink input supports LPCM 44.1/48/96kHz and compressed bitstream (Dolby Digital, DTS) formats. Toslink input can be mapped to any of the above AV inputs. The audio stream is forwarded as-is to HDMI transmitter.
AV input/output adapter
A custom adapter (shown below) can be used to connect
- VGA or component input sources into SCART
- SCART-RGB or component input sources into VGA
A fully wired SCART or VGA cable needs to be connected between the adapter and OSSC Pro board. Design and gerbers are available here. Pre-assembled adapters may become available in future.
Basic setup & usage
Connectivity
Connect your AV sources and display to OSSC Pro.
Power
OSSC requires an external DC power supply. A unit that outputs 5 volts DC with at least 2 Amp (with any expansion cards and/or HDMI adapters 2.5A is highly recommended). The tip must be 2.1 x 5.5mm and centre positive.
Do not use a power supply rated for AC output, or a power supply rated higher than 5 volts DC. An overvoltage protection (5.5V threshold) is present but extensive misuse can damage the board.
After connecting power, OSSC Pro enters standby mode which is indicated by red LED.
Remote control
OSSC Pro operates with a dedicated infrared remote. Key functionality is listed below.
- POWER: Power the device on or off
- INFO: Displays detailed timings of video input and output. Also displays firmware version
- KEYPAD / 0-9: Selects AV source and input format. See remote picture on the side for reference
- MENU: Activates/deactivates OSD menu
- OK: Selects sub-menu or function
- BACK: Returns to previous menu level or from info page to normal source display page
- UP/DOWN: Selects next/previous menu option or next/previous input when not in menu
- LEFT/RIGHT: Option value -/+
- OSD: Switches between different OSD modes (Full, SImple, Off)
- P-LM, A-LM, SCL: Select respective operating mode
- LM.MODE: Select multiplication target for LM modes
- LM.DIL: Select deinterlace mode (Bob / Noninterlace restore) for LM
- SCRSHOT: Reserved for future use
- P.LOAD: Open a menu to load profile
- SL.INT+/-: Hotkeys for adjusting scanline strength
- SL.MODE: Hotkey for scanline mode selection
- SL.TYPE: Hotkey for selecting next "Scanline type" option value
- SL.ALIGN: Hotkey for scanline alignment selection
- PHASE+/-: Hotkeys for sample phase adjustment
- P1-9: Reserved for future use
- SCL.RES: Scaler output resolution selection
- SCL.FL: Scaler framelock selection
- SCL.S.ALG: Scaler scaling algorithm selection
- SCL.D.ALG: Scaler deinterlace algorithm selection
- SCL.AR: Scaler aspect ratio selection
- SCL.ROT: Reserved for future use
- SCL.ZOOM: Open scaler size adjustment menu
- SCL.PAN: Open scaler position adjustment menu
PCB buttons
- BTN: Enter / exit menu
- JOY: 4-directional joystick switches input or test pattern mode when not in menu. Inside menu it provides navigation with the added push function to enter sub-menus
Status LEDs
- Green: Power on. Temporarily off when IR remote code detected
- Red: Standby indicator. When device is on, red LED flashing indicates resyncing to input
- Blue: Framelock
Getting started
Turn on the board by pressing power button on remote or by holding the on-board button for a couple seconds. A 480p test pattern should show up in the monitor. Turn on the video source and select correct input.
The firmware has 2 primary operating modes: line multiplier and scaler. Line multiplier is reminiscent of classic line doublers and OSSC while scaler works more like video processors like VP50 or Framemeister. In general scaler mode offers more flexibility and easier usage via fixed output resolution and (optionally) fixed refresh rate. Some users may prefer to stay with strict multiplication to preserve the original look as much as possible, though. The mode can be switched from "Output opt -> Operating mode" on the menu. Main menu has matching sub-menus for each of the 2 operating modes which are accessible even if the said operating mode is not active. Most important properties of these modes are listed in the table below.
| Pure LM | Adaptive LM | Scaler – framelock | Scaler - no framelock | |
|---|---|---|---|---|
| Latency | max 2 lines | Max 60 lines | ~1 frame | 1-2 frames |
| Display compatibility | Variable | Very high | Very high | Full |
| Deinterlace alg. | Bob, Noninterlace restore | Bob, Noninterlace restore | Bob, Weave, Motion adaptive | Bob, Weave, Motion adaptive |
| Scaling alg. | X: oversample, integer; Y: integer | X: oversample, integer; Y: integer | X: oversample, polyphase; Y: polyphase | X: oversample, polyphase; Y: polyphase |
| Input mode switch delay | Very fast | Very fast | Fast | Instant |
| Transformations | Pan | Pan | Zoom, Pan, (Rotate) | Zoom, Pan, (Rotate) |
| Postprocessing opt. | Scanlines, Border, Masks | Scanlines, Masks | Scanlines, Masks, BFI | Scanlines, Masks, BFI |
Test pattern
Settings
Firmware update
Firmware is updated via microSD card. Download latest release from github, rename the .bin file as ossc_pro.bin and place it at the root of FAT32-formatted SD card. Launch upgrade via Settings menu.
Firmware update via JTAG
Firmware can also be updated via the JTAG connector and a suitable programmer such as the terasIC USB Blaster. A tutorial on how to do this is available here.
Firmware changelog and roadmap
v0.69
- Initial release
Older versions
Scheduled improvements
- Lower scaler mode latency
- Rotation
