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ADV7403 ADV7842 and ADV7850 chips

I am about to start a composite and s-video signal digitization project. Before i get started i need to establish which of your chips to use. I may as well start with what ever your current chip is as I may have been reading old internet webpages.

I have been looking keenly at your ADV7403 chip. Can you tell me whether this has been updated by your ADV7842 and ADV7850 chips and are there even any later chips than these? I could have easily missed something on your website.

Outputs required are digital(s-pdif)  for PC card capture and HDMI for the TV.  I will also require the 3D comb filter and TBC facilities mentioned for these chips in your datasheets. I will also require stereo inputs for the HDMI TV output.



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  • FormerMember
in reply to RagTag +1 verified

Audio CODECs can be found here

CODECs come with output DACs but you don't have to connect or use them them.  The key you are looking for is I2S bus…

  • FormerMember
    0 FormerMember

The ADV7842 has an input HDMI port and the ADV7850 has both input and output HDMI ports.  The analog sections are very similar. Both have 3D comb and TBC.  TBC was used to correct issues with old VCRs so I'd be surprised if you need it for modern systems.

The ADV7403 does not handle HDMI directly.  It only has a digital input port, not HDMI decoding.

If you need HDIM input and output plus analog decoding plus audio insertion I'd look at the ADV7850 single chip solution.  The ADV7842 is great where you need HDMI input and analog decoding feeding an FPGA or a ADV7511.  Note  these chip only handle HDMI 2.0 spec.  Do you need to handle HDMI 2.1?

Also keep in mind you will need to be an HDMI and HDCP adopter to use these chips with HDCP keys.

If you can include a list of supported inputs and outputs with formats required we can point you to a possible solution. 

  • Thank you very much for your informative reply. What i need to do first is to get the chips sorted out.

    input signals

    I have 2 input analogue Video signals to process:-

         1) composite (CVBS) from a laserdisc player
           1.1) Hence the need for an excellent comb filter to split this composite signal into its S-Video Y & C signals.

         2) S-video signal from VHS players
            2.1) And from the Lasedisc Y&C signal just mentioned
            2.2) VHS players - Hence the need for a TBC.

    Output signals

     I need 2 output signals:-

         1) Digital output signal for input into a computer PC capture card.
         2) HDMI output signal for input into a TV
            2.1) This will also need stereo input sockets to take the audio signal from the 2 input sources above.  

    What Chips do i need?

    How does the above translate into chips? And this is where i need your help. Can you sort me out here.    

    first possibility. Have 2 seperate chips in use on 2 seperate boards:-

         1) ADV7842 to take the input sources listed above and create a digital output signal for input into a computer PC card .
         2) ADV7850 to take the input sources listed above and create an HDMI signal for input into a TV.

    second possibility. Have 2 connected chips available:-

         1) ADV7842 to take the input sources listed above and create a digital output  for input to a PC card and ADV7511
         2) ADV7511 to take the digital output from the ADV7842
            2.1) to create the HDMI output signal for input into a TV.       

    I have a problem with the ADV7511 - its datasheet does not show an HDMI output connection. Can you update me on this.

    HDMI 2.0 will do the job very nicely.

    Hope the above makes sense. If i have anything wrong then please correct me on it.


  • FormerMember
    0 FormerMember in reply to RagTag

    6) The ADC sampling rate matches the input format rate.  For example if the input is CVBS then the sampling rate will be 27MHz.  If it's 1080p60, then it's 148.5MHz

    7) The ADV7842 is only designed for one specific DDR, K4H561638J.  Bandwidth through the memory is not an issue since it's only used for CVBS video streams. It's a 256Mb, part

    8) It's U22 in the picture.  Implementation is shown on the schematic

    9) Yes, you will need an analog to I2S converter connected to the ADV7511.  One of ADI's main product lines are audio encoders/decoders.  I am not as familiar with ADI audio lineup but when the time comes we can definitely help you here.  I've used the ADAU1761 on my last design and it worked well.

    10) If you look at page 8 on the schematic you will see the I2S bus connecting to the ADV7511.  These pins come out to the header J4

    As far as indicator lights go, When the ADV7842 powers up it must configured by a uProcessor.  On the eval board we use a BF524.  Almost any uProcessor can be used as long as it can drive the I2C bus and has enough memory to hold scripts.  The uProcessor can monitor 7842 registers and set indicators as needed.

    With the eval-adv7842-7511p, AvesBlue has a probe function that can simulate indicators you are looking for.

    Hope this helps

  • You have brought my attention to the fact that I really need to get to grips with the computer capture end of the conversion system.  

    I do want to capture raw video footage from composite and s-video input.   

    Can the ADV7842 (by itself - no ADV7511 connected)  be switched between  "12-bit 4:4:4 and 10-/8-bit 4:2:2 DDR pixel output" just as the ADV7403 can?.

    I would really like to capture video at 12bit 4.4.4 on the computer. The method of capture on the computer has to be sorted out as yet.


  • FormerMember
    0 FormerMember in reply to RagTag

    The ADV7842 can easily switch between output formats.  In UG-214, user guide check output appendix D.

    I suggest staying with SDR formats.  The pixel rate is the same between DDR and SDR, it's just that the LLC is running at 1/2 the pixel rate.  DDR is harder to capture and intended mostly for FPGA interfaces which have hardware specific DDR receivers.

    As far as ranking pixel bus formats from best to worst it goes

    4:4:4 -> 4:2:2 -> 4:2:0

    4:4:4 needs 3 8/10/12 bit busses

    4:2:2 needs 2 8/10/12 bit busses

    4:2:2 extrapolates color data between pixels so you lose some of the original data.  Compression technique to lower data rate/bus widths.

    As far as bus widths

    3 x 8 bits provide ~16 million colors

    3 x 10 bits provide ~1 billion colors

    3 x 12 bits provide ~69 billion colors

    As far as color space goes RGB is better then YCbCr regardless of bus width.

    I've seen some studies that show humans can only differentiate up to ~10 million colors. I've never understood why we need more then 24 bit color.  Personal opinion.  (Is it a marketing plus to say 'we do deep color')  The only reason I can think of to use deep color is that any artifacts created by post processing is covered up in the lowest bits and won't be seen by the eye.  There's also a spec for 48-bit color.

    I'd like to know why your product needs deep color.  What do you gain from it?

    The HDMI (ADV7511) can carry all the formats mentioned above up to 4:4:4 36 bit bus.

    As you sort through all your video issues may I suggest the video bible I use, Video Demystified.  Available as   pdf or paper book from amazon.  

    I hope this helps,  any more question I'll be here

  • Are you saying that the evaluation board can send a 12 bit (or is it 36 bit) 4.4.4 RGB video signal at maximum sampling rate (27mhz you said for Composite, s-video) through the ADV7511 hdmi output connection to the computer? This should not involve any codecs or compression as  i do not want any. This would provide a means to an end as it would solve my PC capture card  requirement as recent investigations have, as you said, shown most capture cards these days have and HDMI connections, they do not have the old analogue connections or even digital connections. Providing the capture card does not mess with the signal and just allows the signal to be written asit  is to a disk drive file that would keep me happy. That would take care of the hard work. Does this require the use of HDCP keys? Hopefully not, but HDCP keys will still be necessary TV output. I do not want to burden the process with license protection.  

    I have looked into PC software for capturing the digital signal to the computer and so far Cyberlink Power Director and NCHsoftware sound promising. What do you use?.

    As for deep colour i have not even considered that.

    My intention is to lay down binary ones and zeroes as good as they can be from the input sources and take it from there. Cleanup and editting processes will  follow. I don't see that reducing the amount of chroma with 4.2.2 is necessary with the power of computers these days. And why loose data on capture? That  can be done later if necessary.  But its nice as a lower spec option if i choose to use it. So 4.4.4 (RGB) for capture.  

    For  computer capture I had been thinking along the lines of using the ADV7842 outputs somehow, converting them to a .DV-dif file/signal somehow and sending  them to the PC  using A USB connection??? This is all speculative of course. Software on the PC would then capture this signal and write it to disk.   

    Can you clarify what you said about DDR as this has thrown me somewhat. Where does it fit into what has been said?

    Thanks for the mention of the book. I may read it but i have the feeling that it is one of those items that will take me too deeply into the theory of the  conversion subject which i see as cables, and electronics at the moment.


  • FormerMember
    0 FormerMember in reply to RagTag

    1) About HDCP keys.  You are only require to handle HDCP keys if the source requires them.  DVRs and set top boxes implement HDCP because their video sources require the license for copy protection.  HDCP only works over HDMI connections.  Analog sources don't have any HDCP so no need to worry about them.  The ADV7842KBCZ-5P has no keys so its not a problem, can't break the copy right infrigement..  

    2) I don't use PC capture cards.  I use HDMI analyzers to capture images and a lot more information.  Many of the current capture cards are USB dongles connected over USB 3.  They come with analog or HDMI inputs.  The old fashion capture card that plugs directly into the PC backplane bus are not that common anymore.  Regardless these dongles load the video stream into main memory as a raw file or probably a converted file like DV.  The software packages you mentioned either taps directly into the stream or works with saved files.  They are basically video editors.

    3) All the 7842 can do is convert the video input (either HDMI or analog) into a 24-bit stream.  How it gets into the PC is another matter.  This is what the video to USB dongles do.  So are you designing a USB dongle?

    4) 12-bits per color plane is deep color,  RGB444 would have 3 color planes making a 36-bit bus.

    5) Somewhere above you said you wanted to use 24-bit DDR.  I was just saying SDR is easier to work with.

    6) The first several chapters of the book will give you information on exactly what color space are and what 444,422 mean and how to work with BT601 and BT656.  BT601 and BT656 are an 8-bit bus format for CVBS formats.

    Going back to the start of this thread you were looking to use the 7842 for it's TBC and 3D comb features for VCR outputs and now wanting this stream in RGB444 format.  The real issue is how are you going to get the RGB444 stream into the PC for editing by those software tools.  I don't know of any RGB444 to USB bridge implements.

    It could be done but probably needs FPGA solutions the plug directly into the PCI bus of the PC or as a dongle adapter running over USB.  That's lots of work unless you can find something off the shelf.

    It might help if you drew up a diagram of where you want the video stream to flow and in what format. Include lots of details that we can throw darts at.

    If I were to do this I'd build my system like this

    analog inputs -->

        ADV7842 for TBC and 3D comb, 36 bit digital output -->

            ADV7511 to convert to a HDMI stream -->

                HDMI to USB dongle -->

                    Video editing software.

  • USB Dongle - No, i am not building a USB dongle. Thats way out of my league. So can the ADV7511 HDMI output be used to transfer an output signal to a PC capture card? There are still quite a few PC PCIe Capture cards out there with HDMI input connections. Black Magic are still making them.  As i said, that  would solve my capture problem.  I am just trying to go with whats available on the markets.   

    HDCP keys - do i still need a 7511  with HDCP keys to display the now converted composite and s-video input signals on an lCD/ LED TV?

    Capture software - the packages mentioned have capture facilities which are required for eg webcams and hopefully PC capture cards. I need to investigate  these packages more.  If they will capture without applying codecs or compression then that is what i want.  
    DDR - Does DDR refer to double data rate  or the DDR memory on board the 7842/7511 evaluation board? If the 12 bit colour plane  you mention is SDR then that  is what i want, not DDR.  I am still not sure what DDR means here.

    CVBS and S-video capture - can the 7842 convert these inputs to 36 bit RGB 4.4.4 digital output or is the conversion limited to 8 bit.

    Workflow - more or less the same as what you laid out
        analog inputs -->

        ADV7842 for TBC and 3D comb, 36 bit  RGB 4.4.4 digital output -->

            ADV7511 to convert to a HDMI stream -->

                HDMI  to
                    1)  PC capture card -->

                    Video capturing software.
                    2) LCD/LED TV

    WIll the ADV7511 output the full 36 bit RGB 4.4.4 digital stream as is, or will it convert or compress it in some way?  Does converting to an HDMI stream involve compression?  

    Will the  36 bit RGB 4.4.4 digital stream display, via an HDMI cable,  on an LCD/LED TV?    


    Perhaps i am over egging the pudding. I usually do. All that is required is to write the 36 bit RGB 4.4.4 digital stream to a USB stick. How about using the USB port on your evaluation board? Favourite for the USB drive would be a 1TB PCIe drive card, M.2,  in a USB/ PCIe caddy, both are are available on Amazon. The Caddy has a PCIe to USB bridge at USB 3.2 gen 2 whatever it is, anyway, 10 Gb/s, far faster than any USB stick. So thats the terrific speed of a first class USB connection, the blazing speed of of a PCIe drive  plus the capacity of the PCIe drive, 1TB!  That would really do the job! Then, after capture,  simply transfer the PCIe drive and caddy to a USB port on the computer for further processing. PC capture card dispensed with!  Evaluation board now purely for TV display!   

    Hope thas useful  

  • FormerMember
    0 FormerMember in reply to RagTag

    1) The ADV7511 outputs HDMI so it will work with either PC capture cards or TV's

    2) You do not need HDCP keys to output to TVs.  HDCP keys are only requested from TVs if the source requests them and analog sources will never request them.  So no key problems.  The ADV7511 comes with keys but since the 7511 is only a transmitter, the powers to be don't care if you transmit encrypted or plaintext.  You can turn it on and off as needed.  Now the powers to be do care about receivers with keys since with them you can violate copyright rules.  Bottom line is TVs don't care, they'll display plaintext video just fine.

    3) DDR == Dual Data Rate, SDR == Single Data Rate.  Basically SDR present new data on only a rising or falling clock edge while DDR presents new data on both clock edges.

    4) Capture cards can replace the dongle.  I just though a dongle would be more more convenient then opening up a PC to install a PCI card.  (Hard to do on a laptop also)

    5) Basically the ADV7511 is just a parallel to serial converter.  For video streams compression only occurs when you do 444 to 422 conversion, the pixel colors are compressed from 8 bytes down to 4 bytes.  This conversion can be disabled.

    6) RGB444 over HDMI will display on TVs.  

    7) The USB port on the eval is a control port only and has been deprecated.  Now we only recommend using the serial port for control.  (Software issues).  It cannot carry video.

    8) BIG IDEA.  The hard part is writing a 36 bit stream to a memory card.  This is what the capture cards/dongle do.  Remember video is a continuous data stream while USB to memory transfers are block transfers.  How do you convert a continuous streams into block transfers.

    I think I addressed most of the questions.  

  • AnNother great answer. It's all coming together at last! It looks like i can get everything i want out of your evaluation board.

    I think thats about all on the video side.

    I wish to start a new series of AUDIO Q/A as this video one is getting long 

    Big idea  - take 2

    I appreciate what you said about writing a 36 bit stream program but applications like nchsoftware and Cyberlink Power Director do it so the question is how. The real problem here is not to let the writing to disk of the recorded input stream  interrupt the recording of the input stream so the write to disk function would have  to be a lot faster than the recording of the input stream.

    This takes me back to my programming days where, when running the programs i had written, they would be given a number of input buffers by the OS which would be filled and controlled by the OS.  As you said, this is a block driven process. The applications i mentioned must be using a similar technique of having a number  of input buffers which the application will have  to empty a lot faster than the input stream can fill them up.

    How could this be done?

    This is a conceptual solution.

    Lets start with the USB PCIe caddy i mentioned at 10Gb/s with a USB 3.2 gen 2 (or whtever it is) on the PCB  that can write at something approaching 10Gb/s.         

    The program to record and write the input stream:-

        1) has, lets says, 6 buffers at, lets say, 32KB.

        2) the buffers are in ram (the evaluation board DDR chip or an upgraded or dedicated  memory chip)

        3) When  a 32KB buffer is full the program moves onto the next buffer and the full buffer is written to disk (the PCIe drive i have just mentioned). Each full buffer has now become a "block"
        4) The  32KB of a full buffer could be written to PCie disk all at once or, if such a large write to PCIe would interupt the recording of the input stream, at smaller amounts, lets say 4KB, that could make use of microsecond gaps when the input stream is not being recorded to a buffer.

        5) the program cycles around these 6 buffers sequentially.

        6) Making sure the buffers are empty before they are required again is the clever bit.  
    An alternative is to write the input stream straight to PCIe card which would save a lot of messing around with buffers and memory and, providing the write  to PCIe is faster than the rate at which the input stream is arriving, would be a very neat solution.

    How about a Thunderbolt 4 connection straight to a PCIe card, ie miss out USB altogether!  

    Whats recorded on the PCIe card is a single file, lets say 300GB of yuk.

    On completion of the recording the PCIe caddy is transferred to a computer where there is a program that can format the 300GB of yuk into a raw file of, lets say, 80 byte dif blocks (80bytes seems a bit small to me).  The point about the raw file is that it can now be be editted by an appliction that can process raw files.

    This is not a bad system with all parts of the process, capture ->  format -> edit, split up into separate jobs. The capture part, which is the difficult and partly unknown part of the process, has been well and truly isolated from the rest which can now proceed at a more leisurely speed.  

    OK, its a thought

  • FormerMember
    0 FormerMember in reply to RagTag

    All PC capture cards (let's use pexhdcap60l2 as an example) will have some sort of frame buffers that they ping-pong back and forth to capture video streams using an ASIC or FPGA.   Then it normally compresses the video stream into H264 format and then sends the packets over the PCIe interface to the main memory.

    I believe H264 can be set as lossless.  Compression still happens, you just don't lose any raw data.  Once in main memory you can decompress it back to RGB.  I just don't know of any video RGB file formats.  The video editors only work with files in main memory, not directly with the capture card.  It may look like editors work directly with the capture card however the the video is just moved in smaller blocks then an entire file.  (Something similar to pipes)

    video --> capture --> compression(H264) --> PCIe --> main memory --> video editor

    You can't sent video directly to main memory over PCIe.  PCIe is a bus and must be shared so PCIe packets must be created and sent only when the bus is free.  This is what the PCI interfaces do.

    Thunderbolt is similar to USB except its specs include video transmission.  All video is packetized. (Uses the same USB-C connector)

    On another note, originally we started with digitizing S-Video VCR outputs.  The S-video output my only use an 8-bit DAC.  You don't need 12-bit of data to capture an 8-bit source.  Nothing is gained by the extra 4-bits, it's just noise at best.

    If you want to start talking about audio then please start another thread, this one is kind of long already and really dedicated to video.

  • Do you have a parametrics list for ADC only chips. I still require 192/24bit with I2S out . I no longer need DAC facilities.

  • Reply Children
    • FormerMember
      +1 FormerMember
    in reply to RagTag

    Audio CODECs can be found here

    CODECs come with output DACs but you don't have to connect or use them them.  The key you are looking for is I2S bus, 2 input channels (ADCs) and 192k sampling rate.