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Altera_Forum's avatar
Altera_Forum
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16 years ago

Video IP Scaler control

Hello,

I'm having trouble using the Scaler in the Video IP suite. I have instantiated the scaler using the megawizard and my control logic is custom.

I have instantiated a fixed scaler in my system and it works just fine (no input or output sizes needed on the ST or MM interfaces). When trying to set the input and output image sizes the scaler accepts the first few pixels and then deasserts din_ready never to assert it again.

I am configuring the scaler in the following way.

Reset Scaler.

Avalon MM interface :

Set go bit to zero.

Wait for status bit to be zero.

Set the go bit to one.

Avalon ST interface :

Send control packet (startofpacket & Data = 0xF)

Send Width and Height nibbles.

Send control packet (endofpacket & Data = 0x0(progressive))

Send control packet(startofpacket & Data = 0x0(Video data))

start sendig data.

the scaler takes 3 pixels and then deasserts din_ready and the video

flow stops.

How do the width and height nibbles fit into a parallell data stream of 8 bits per pixel and 3 color planes in parallel. the documentation is a little unclear and I have tried some different nibble groupings.

Any help or pointers would be greatly appreciated !

Thanks :D

21 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    The data is aligned as follows in the three color planes 8 bit RGB, 24 bit data bus into the Scaler following the ready latency of 1.

    sp d0 d1 d2 ep

    19:16 x W1 H2 x x

    11:8 x W2 H3 H0 x

    3:0 F W3 W0 H1 0x0

    sp start of packet

    ep end of packet

    Width nibbles W(3-0)

    Height nibbles H(3-0)

    interlace at end of packet 0x0

    this is where I was not able to find a lot of documentation

    thanks for the reply
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    should be this for 8 bit data in

    sp w3 w2 w1 w0 h3 h2 h1 h0 interlaced eop

    so for 24 bit

    byte 2 | w1 | h2 | interlaced

    byte 1 | w2 | h3 | h0

    byte 0 | w3 | w0 | h1

    | sop | | eop

    where the w and h values are all nibbles

    spacing sucks. | is a delimiter
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    dwesterg beat me to it. I'll make one modification:

    Here is what the control packet looks like. I'm assuming 8-bits per color plane with 3 color planes in parallel. The pertinent bit of the 24-bit dout_data would be as follows for the individual cycles: 

    cycle         1     2           3           4
bits 3:0      0xf   w    w    h
bits 11:8       0   w    h    h
bits 19:16      0   w    h    ilace
              sop                           eop

    Jake
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Thanks guys,

    I had it mostly correct except for end of packet. Rebuilt and ran but same problem din_ready from the scaler gets deasserted after 3 pixels :rolleyes: on the avalon MM side i'm just writing in the output width and height as 32 bit unsigned numbers and setting the "go" bit. Could there be an issue there ?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Did you look at the dout signals. Is something hung up downstream?

    Jake
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    This is a custom video processing pipeline that I am adding a scaler to. The scaler was generated with the megawizard and instantiated in my system.

    When I change to a fixed scaler (No Avalon MM interface) the scaler works fine. There is not an issue with data flow, I have to be setting up the run time parameters incorrectly....

    thanks
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Well, it could be your setting the parameters incorrectly. It could also be that your VIP control packets are incorrect. The scaler ignores control packets when it is set to a fixed size so it likely wouldn't have seen any issues.

    One last thing ... are you properly giving "0" when you give the startofpacket for the actual video packet?

    Jake