Reference Guide
Quite short, purpose of this guide, other documentation.
Either here, or in the Adding a new Profile Tutorial, we need some diagrams that cover:
- Capture areas (H/V Offset and Min/Max Width/Height)
- Overscan (Min/Half-Way/Max/Auto)
- Scaling (Integer/Fill 4:3/Fill All)
This is the initial menu displayed when the menu button is pressed and can be used to setup RGBtoHDMI for first use and to select all the other menu options
This menu allows various information to be displayed and also allows rebooting and programming of the CPLD.
Displays technical information about the video source and the Pi's frame buffer.
Displays technical information about the system including CPLD version and Pi clocks etc.
Displays current calibration summary
Displays current calibration detail if available
Displays current calibration raw data if available
Displays credits
Selecting will reboot the Pi.
Useful if the hat is plugged into a Pi which doesn't have the reset header fitted or available
Allows the CPLD to be reprogrammed
Sets user preferences
Values: Normal / Monochrome / Green / Amber
Changes the output to simulate a monochrome, green or amber monitor.
Values: Normal / RGB/YUV / G/Y
Inverts either all three RGB/YUV video signals or just the Green/Y signal.
Values: 0-255
Changes the border colour (the area of the screen not being written to by the capture code).
Values of 128-255 fill the whole screen and this is used for the colour test profile.
Values: Off / In Band Commands / NTSC Artifacting
In Band Commands allows the computer to reprogram the palette by sending special pixel combinations.
NTSC Artifacting simulates the false colour effects used on NTSC systems to generate colour from a monochrome source.
The above options are still under development.
Values: Off / On
Turns scanlines on and off.
NOTE Scanlines will not be visible when the menu is on screen.
Sets the intensity of the scanlines.
0 = black, 15 = very slightly dimmed compared to the non-scanlines.
Values: 0-15
Values:
- None
- Simple Bob
- Simple Motion 1
- Simple Motion 2
- Simple Motion 3
- Simple Motion 4
- Advanced Motion
Determines the algorithm used to deinterlace teletext displays such as the BBC micro's mode 7.
Simple Bob used the "bob" algorithm which introduces vertical shimmer.
Simple Motion uses 25Hz motion detection and the level determines the tradeoff between weaving and fizzing artifacts
(1 = most "weave", least "fizz", 4 = least weave, most "fizz").
Advanced Motion should be used for best results and has no weave at all with minimal "fizz". The other options are only required for earlier CPLD versions prior to v3.0.
Values: Even / Uneven (3:2>>4:3)
Converts a 3:2 teletext image to 4:3.
When using integer scaling, the BBC's mode 0 will normally fit on the screen with a 4:3 image but due to the different (12Mhz) pixel clock of teletext it will fit onto the screen with a 3:2 aspect ratio.
Enabling the "Uneven (3:2>>4:3)" will squash the horizontal resolution of teletext so that it has a 4:3 aspect ratio to match the other modes.
When using "Integer/sharp" scaling this can result in some unevenness in teletext characters.
Values: Even / Uneven (3:2>>4:3)
Converts a 3:2 progressive image to 4:3
Same as Teletext Scaling but for non-teletext modes.
This option will only have an effect on 3:2 screens and is generally only useful for the Camputers lynx and Oric which have 6 Mhz pixel clocks.
Values: Auto / Max / Halfway / Min
Controls the size of the capture area.
Min will use the minimum area from the geometry menu.
Max will use the maximum area from the geometry menu.
Halfway uses values halfway between the above two.
Auto selects the best capture area.
With "Integer" scaling, Auto picks a value between the Min and Max settings that is an integer multiple of the screen resolution.
With "Fill" scaling, Auto always uses the Max area.
Values: Off / On
The Pi can capture a frame of the displayed video and write it to the SD card as a PNG file.
Normally it writes a smaller image than the screen area (usually half size) but if you turn ScreenCap scaling on it will always capture at the screen resolution.
Adjusts setting that are generally left unchanged
Values: Always 8x8 / Auto 12x20 4bpp / Auto 12x20 8bpp
There are two fonts used by the software, a small 8x8 and a larger 12x20.
Always 8x8 will always use the 8x8 font.
Auto 12x20 4bpp will use the 12x20 font in 4bits per pixel modes but switch to the 8x8 font if the text won't fit on the screen. In 8 bits per pixel mode the 8x8 font is always used.
Auto 12x20 8bpp will use the 12x20 font in both 4 and 8 bits per pixel modes but switch to the 8x8 font if the text won't fit on the screen.
Values: Off / On
Turns on a red bar which shows the phase relationship between the input video signal and the Pi's video output. If the bar is not moving it means the two are locked together.
Values: Genlocked (Exact) / 1000ppm Fast / 2000ppm Fast / Unlocked / 2000ppm Slow / 1000ppm Slow
Genlocked (Exact) means the Pi's video output is locked to the source video. This is the normal mode of operation and is used to keep the video in sync and prevent tearing or glitching of the video signal.
Unlocked means the Pi runs independantly of the video source. This will result in tearing unless the number of buffers is increased to 3 or more which will significanly increase lag.
The Fast/Slow settings run the Pi faster or slower by that number of parts per million and these are normally used for testing only.
The led next to SW1 on the board indicates the genlock state:
Off = Unlocked
Flashing = Locking in progress
On = Locked
Periodically the Pi will need to re-lock to the source and this is indicated by brief flashing of the led.
If the led continues flashing it means the Pi can't lock to the source which is usually due to the input frame rate not being the same as the Pi's output frame rate.
Values: 35-140
This sets the position of the red bar and this should generally be towards the top of the screen to minimise lag.
Values: Slow (333PPM) / Medium (1000PPM) / Fast (2000PPM)
Controls the rate at which the Pi locks to the video source.
If your monitor blanks briefly during genlocking (when the led is flashing) then try reducing the genlock speed.
Values: -5% to +5% / Full Range
Controls the maximum adjustment of the Pi's video output when genlocking.
-5% to +5% limits the adjustment range to those values.
e.g. if the Pi is set to 50hz output it will only adjust between 47.5Hz and 52.5Hz so if the source is 60Hz it will never lock and you will get a warning on the menu status line.
(In such a case the Pi's video output should be switched to 60Hz)
Full Range allows the Pi to lock to any frequency so it would change the 50Hz to 60Hz. This option is not normally recommended as it can result in very non-standard video outputs that the monitor will be unable to display.
Values: 0-3
Controls the number of frame buffers used to buffer the video signal. Each one adds 1 frame of lag to the output.
The default is 0 and it is only useful to use other options to prevent tearing if genlock is disabled.
Values: Start / End
Sets the position of the Return menu option to the start or end of each menu.
TODO: We should drop this from the OSD, as it gets save per-profile wich is very confusing
Switches on vertical lines in the video capture area, used to check alignment.
Sets the capture area sampling size, clock and sync etc.
Values: Normal / Set Min/Offset / Set Maximum / Set Clock/Line / Fine Set Clock
This setting makes it easier to setup the associated values below.
When setting the offset and minimum values, select "Set Min/Offset" which reduces the capture area to the minimum values and you can adjust these 4 values so that exactly the screen output of the source is captured.
Similarly select "Set Maximum" before adjusting the maximum values as this forces the capture area to the maximum values
Select "Set Clock/Line" when setting the clock and line values as this disables the clock tolerance which is required when making clock and line adjustments. The clock is adjusted in 1000Hz increments
Finally "Fine Set Clock" changes the clock increment to 1
This setting is automatically returned to "Normal" when you leave the geometry menu.
Values: 0-512
Controls the horizontal position of the capture area
Values: 0-512
Controls the vertical position of the capture area
Values: 100-1920
Sets the minimum number of horizontal pixels to capture.
This is normally set to the number of pixels output by the source computer at it's highest resolution.
e.g. for a BBC micro this would be 640.
Values: 100-1200
Sets the minimum number of vertical pixels to capture.
This is normally set to the number of pixels output by the source computer at it's highest resolution.
e.g. for a BBC micro this would be 256.
Values: 150-1920
Sets the maximum number of horizontal pixels to capture.
This is normally set to a larger value that covers the border area and that usually results in a 4:3 ratio with the max vertical height for square pixels or 8:3 ratio with 1:2 pixels like the BBC micro.
e.g. for a BBC micro this would be 768.
Values: 150-1200
Sets the maximum number of vertical pixels to capture.
This is normally set to a larger value that covers the border area and that usually results in a 4:3 ratio with the max horizontal width for square pixels or 8:3 ratio with 1:2 pixels like the BBC micro.
e.g. for a BBC micro this would be 288 (768x288 = 8:3).
Values: 0-8
Sets the horizontal pixel aspect ratio (not the screen aspect ratio)
This is used to determine the integer scaling ratio. If it is set to 0, integer scaling will try to fill as much of the screen as possible without maintaining a fixed aspect ratio.
e.g. for a BBC micro this would be set to 1 (1:2 aspect pixels)
When you adjust this value some helper info is displayed on the status line
Values: 0-8
Sets the vertical pixel aspect ratio (not the screen aspect ratio)
This is used to determine the integer scaling ratio. If it is set to 0, integer scaling will try to fill as much of the screen as possible without maintaining a fixed aspect ratio.
e.g. for a BBC micro this would be set to 2 (1:2 aspect pixels)
When you adjust this value some helper info is displayed on the status line
Values: Normal / Double Height / Double Width / Double Width+Height
The frame buffer is normally set to a value between the minimum and maximum values above but sometimes it is useful to double the size of the frame buffer vertically, horizontally or both as that can improve the quality of the scaled output. Setting this option doubles the size of the buffer in the appropriate direction.
e.g the BBC micro with 640x256 uses the double height option for a frame buffer of 640x512. Smaller resolutions like the Atom or Spectrum should used both.
Also if you want to use scanlines then Double Height must always be enabled.
Values: 4 / 8
Sets the frame buffer to use 4 or 8 bits per pixel.
If you are capturing 6 bits per pixel this should always be set to 8 bits per pixel.
If you are capturing 3 bits per pixel this can be set to either value.
Values: 1000000 - 40000000
i.e. 1MHz to 40MHz
Sets the pixel clock frequency used to sample the incoming video.
Starting to adjust this value automatically sets the setup mode to "Set Clock/Line"
When you adjust this value some helper info is displayed on the status line
Values: 100-5000
Sets the number of clock cycles per video line on the incoming video.
Starting to adjust this value automatically sets the setup mode to "Set Clock/Line"
When you adjust this value some helper info is displayed on the status line
Values: 0-100000
Sets the range of adjustment in PPM of the above clock frequency when locking to the incoming video.
If the adjusted clock is outside this range then the previous frequency or default frequency is used. This allows software that creates non-standard video timings to work.
Normally in the range 4500 - 25000 depending on the source.
When you adjust this value some helper info is displayed on the status line
Values: 250-1200
Sets the number of lines per field/frame of the incoming source.
e.g. 312 for PAL 50 Hz sources
When you adjust this value some helper info is displayed on the status line
Values: -H-V / +H-V / -H+V / +H+V / Composite / Inverted
Sets the sync type and polarity of the incoming video source
Values: Auto / Interlaced / Interlaced 160uS Vsync / Non Interlaced
Sets the vertical sync type used by the source.
Auto will switch between the two interlaced types
Values: Progressive / Interlaced Teletext
Sets the type of video used by the source. Most sources are progressive except for teletext which uses interlaced video.
(OLD CPLDs ONLY) Values: Normal / Odd / Even / Half Odd / Half Even
This option is not shown in the menu with latest CPLDs and is used by old CPLDs to sample lower resolution sources like the Atom
This menu varies when used with a BBC micro depending on the video mode.
In mode 7 the following options are available:
In other BBC modes and with all other supported computers the following options are displayed:
Values: Normal / Set Delay
This setting makes it easier to setup the Delay value.
Selecting "Set Delay" reduces the capture area to the minimum values and you can adjust the delay value so that the video exactly lines up with the capture area.
This setting is automatically returned to "Normal" when you leave the sampling menu.
Values: 0-5 or 0-7
This adjusts the video sampling point and it can be changed to eliminate any noise in the video signal. This value is automatically set by using the "Auto Calibrate Video Sampling" option in the main menu or using the shortcut calibration on the one of the buttons. The range (0-5 or 0-7) depends on the Divider setting below.
Values 0-7
These offsets are available in BBC mode 7 teletext only and can be used to fine adjust the sampling when used with the non-symmetrical 12 Mhz pixel clock used in that mode.
Values: Off / On
This setting adds an additional sampling delay of half a pixel. It is set as required during Mode 7 auto calibration if the optimal sampling point is at one extreme of the range. For example, if the sampling point is 0-1 or 6-7, then this setting will be enabled to shift the sampling point to 2-5 (i.e. in the middle of the range). This gives scope for incremental adjustment of the individial A-F sampling offsets, without any risk of them reaching the limits.
Values: 6 or 8
Sets whether the master sampling clock is divided by 6 or by 8 to give the pixel clock. This also changes the range of sampling offsets from 0-5 to 0-7.
Values: 0 to 15
Adjusts the fine horizontal position of the capture area that has been set in the Geometry menu.
When used with a BBC micro this value is set automatically as part of the "Auto Calibrate Video Sampling" option.
Values: 3 Bits Per Pixel / 6 Bits Per Pixel / Half-Odd (3BPP) / Half Even (3BPP)
Changes the type of sampling:
3 Bits Per Pixel = 3 Bits per pixel sampling.
6 Bits Per Pixel = 6 Bits per pixel sampling (only works with the 6 BIT board).
Half-Odd (3BPP) = Sample every other pixel (Odd only) at double the pixel clock rate.
Half Even (3BPP) = Sample every other pixel (Even only) at double the pixel clock rate.
The last two options provide increased accuracy of sampling for use with BBC mode7 teletext.
Values: Off / On
In the 3 BIT board when set to on, a TTL buffer chip is switched into the RGB input path to change the logic thresholds from CMOS to TTL which improves logic level detection with some computers such as the Electron although it is not essential.
In the 6 BIT board when set to on, sync is sourced from the Vsync input rather than the normal sync input. This is primarily to support sync on green with the analog board.
When the analog addon board is fitted, the following additional "DAC" menu options are displayed:
The DACs are used to set the thresholds for comparators which allow 3 levels of RGB to be discriminated
Values DC/High Impedance / AC/High Impedance / DC/75R Termination / AC/75R Termination
Changes the way the analog input is handled:
DC/High Impedance = the G signal is DC coupled and all RGB inputs are high impedance.
AC/High Impedance = the G signal is AC coupled via a capacitor and clamp circuit. All RGB inputs are high impedance.
DC/75R Termination = the G signal is DC coupled and all RGB inputs are 75 Ohm terminated.
AC/75R Termination = the G signal is AC coupled via a capacitor and clamp circuit. All RGB inputs are 75 Ohm terminated.
Note the R and B signals are always DC coupled.
Generally, only the DC modes should be used with RGB signals as the AC option is primarily for use with YUV sources.
If AC coupling is selected, the DAC-G setting will have to be adjusted appropriately.
Values: 0 to 255
Sets the voltage of the highest green level above black
Values: 0 to 255
Sets the voltage of the lowest green level above black
Values: 0 to 255
Sets the voltage of the highest red and blue levels above black
Values: 0 to 255
Sets the voltage of the lowest red and blue levels above black
Values: 0 to 255
Sets the voltage of the Vsync input which is also connected to the green signal.
If Input Mux is set to "on" (see above) this can be used to detect sync on green.
Values: 0 to 255
Sets the voltage threshold of the sync input
Values: 0 to 255
The G input is clamped using sync tip clamping in AC coupling mode and this sets the clamping voltage level.
For RGB inputs, this is normally set to 0
When the the CPLD reprogrammed to the YUV version, the following menu options are displayed:
The DACs below are used to set the thresholds for comparators which allow 3 levels of YUV to be discriminated.
Values: Normal / Set Delay
This setting makes it easier to setup the Delay value.
Selecting "Set Delay" reduces the capture area to the minimum values and you can adjust the delay value so that the video exactly lines up with the capture area.
This setting is automatically returned to "Normal" when you leave the sampling menu.
Values: 0-15
This adjusts the video sampling point and it can be changed to eliminate any noise in the video signal. This value is automatically set by using the "Auto Calibrate Video Sampling" option in the main menu or using the shortcut calibration on the one of the buttons.
Values: Off /On
Enables noise filtering in the Y channel
Values: Off / On
Enables noise filtering in the U & V channels
Values: Off / On
Halves the sample rate on the U and V channels (Used on 6847 sources)
Values: Off / On
Inverts the V (R-Y) signal on alternate lines (Required by 48K Spectrum input)
Values Trailing / Leading
Sets whether sync timing is taken from the Trailing or Leading edge of the sync pulse This should normally be set to "Trailing" and only set to "Leading" if there is a problem with the trailing edge of the sync pulse. "Leading" is currently only used by UK101, Superboard and Spectrum 48K
Values Sync Tip / Back Porch Short / Back Porch Medium / Back Porch Long / Back Porch Auto
Switches the type of clamping from sync tip to back porch.
Sync Tip Clamping clamps the incoming Y signal to the bottom of the sync pulse
Back Porch Clamping clamps the incoming Y signal to the back porch level.
The Auto option automatically selects the right length of back porch for the current sample clock.
Values: 0 to 15
Adjusts the fine horizontal position of the capture area that has been set in the Geometry menu.
Values: Off / On
Used to change the behaviour of the DAC-E: Y/V Sync setting (see below)
Values DC/High Impedance / AC/High Impedance / DC/75R Termination / AC/75R Termination
Changes the way the analog input is handled:
DC/High Impedance = the Y signal is DC coupled and all YUV inputs are high impedance.
AC/High Impedance = the Y signal is AC coupled via a capacitor and clamp circuit. All YUV inputs are high impedance.
DC/75R Termination = the Y signal is DC coupled and all YUV inputs are 75 Ohm terminated.
AC/75R Termination = the Y signal is AC coupled via a capacitor and clamp circuit. All YUV inputs are 75 Ohm terminated.
Note the U and V signals are always DC coupled.
If AC coupling is selected, the Clamp type and DAC-G settings will have to be adjusted appropriately.
Values: 0 to 255
Sets the voltage of the highest Y level above black
Values: 0 to 255
Sets the voltage of the lowest Y level above black
Values: 0 to 255
Sets the voltage of the highest U and V levels
Values: 0 to 255
Sets the voltage of the lowest U and V levels
Values: 0 to 255
Sets the voltage of the Vsync input which is also connected to the Y signal.
When Input Mux is set to off, this is used to discriminate the Vsync signal on 6847 sources.
When Input Mux is set to on, this switches the Y input from 3 levels to 4 levels and the value is used to set the threshold for the middle Y level.
Values: 0 to 255
Sets the voltage threshold of the sync input
Values: 0 to 255
The Y input is clamped using sync tip clamping or back porch clamping in AC coupling mode and this sets the clamping voltage level
Values: 0-15
This adjusts the video sampling point and it can be changed to eliminate any noise in the video signal. This value is automatically set by using the "Auto Calibrate Video Sampling" option in the main menu or using the shortcut calibration on the one of the buttons.
Values: Off / On
Enables noise filtering in the Y channel
Values: Off / On
Enables noise filtering in the U & V channels