Hi, I have another problem about scaler, it's right that adding a control port to scaler makes the input resolution changable, but some resolution doesn't work. My data path is listed below. Clocked Video Input(CVI) -> Scaler(SCL) -> Frame Buffer(FB) -> Mixer(with Test Pattern) -> Clocked Video Output(CVO) The settings of SCL please see the attachments During run-time, I changed the output size of scaler to 1024x768, and I started to change the input resolution, all the resolutions above and include 800x600 worked pretty fine. But when I set the resolution below 800x600, like 720x480 or 640x480, it flickered badly. Any reply is appreciated!

This is just a guess. How deep is the FIFO on your CVI block? Because you are upscaling you are going to put backpressure from the scaler to the CVI. It may be that this backpressure is causing an overflow in your CVI. Jake

--- Quote Start --- This is just a guess. How deep is the FIFO on your CVI block? Because you are upscaling you are going to put backpressure from the scaler to the CVI. It may be that this backpressure is causing an overflow in your CVI. Jake --- Quote End --- Hi, Jake, thanks for your reply! Yes, your guess is right, when I change the input resolution 640x480@60 to 640x480@30, which reduced the backpressure on CVI, it worked well, but it seems hard to set a appropriate size for the FIFO of CVI. In the user guide, you know, it mentioned that the latency of scaler is N(Tap)-1 lines, in my understanding, does it mean that a overflow of CVI won't happen as long as the FIFO depth of CVI is equal to or more than (N-1)lines. Again thanks for reply!

It's a balance between clock frequency and fifo size. Basically when you upscale, the scaler has to use the same input line of data more than once to produce the output. This will hold off the input by at least a line. If during that time your CVI FIFO overflows, then you're in trouble. Now if you're running the VIP blocks fast enough, the scaler can chew through that second line of output and start pulling data again from the input before the FIFO gets a chance to overflow. It's actually a fairly complex calculation to find the exact frequency. Taking into account the vertical and horizontal blanking interval and the input sample frequency at exactly what point will your FIFO overflow. However, if you always run your VIP blocks at at least 2X the input clock frequency of any standard that will be upscaled, you'll probably avoid the issue. Jake

Hi ; I'm working with scaler to upscale from 800x600 to 1080P, but I don't have anything in the screen or in the est case I get a flicker. I'm using Altera Cyclone III development board. and here the chain that I'm using in sopc builder. CVI->scaler->video frame buffer -> CVO Does anayone have an resolution for this problem ? thank you. Rabia

Hi, lots of things could be wrong in this system. You need to get this system working first: TPG->CVO (where TPG is the test pattern generator) Then you can try: TPG->frame buffer->CVO Then: TPG->scaler->frame buffer->CVO And finally: CVI->scaler->frame buffer->CVO

scaler problem | Altera Community

32 Replies

Altera_Forum
Honored Contributor
15 years ago
Hi,

I reconfigured the Scaler component for its default settings with 4 taps, the behaviour is the same. Upscaling to 1600x1200 works for input resolutions greater then 800x600, but not for anything below 800x600.

The frame buffer is configured for triple buffering.

Any other ideas?

I've seen people using a pipeline bridge between the frame buffer and the scaler, is this something of value?

Thanks,
Mike
Altera_Forum
Honored Contributor
15 years ago
Hi Everyone,

Just wanted to provide some status for the scaler problem at 800x600 -> 1600x1200 scaling. I replaced the CVI with a test pattern unit and still have the same problem.

The video path is the following:
TP@800x600x60Hz -> SCALER -> FRAMEBUFFER -> CVO

The following scaling tests:

800x600 -> 1024x768 OK
800x600 -> 1280x1024 OK
800x600 -> 1600x1200 Broken!!

It looks like the problem is in either the frame buffer or the CVO. Can one of the Altera guru's please provide some guidance here??? It's looking like a throughput issue post-scaler, what parameter would make sense to change in the CVO & Frame Buffer??

Thanks,
Mike
Altera_Forum
Honored Contributor
15 years ago
If all configurations are OK, maybe you have memory bandwidth problem?
The frame buffer need to access the memory much more frequently at 1600 x 1200 then in 1280 x 1024.
At 1600 x 1200 x 24bit x 60Hz input & output to the frame buffer you need very high memory bandwidth.

Can you give us the details of the SDRAM (DDR) you are connecting to the FB?
Altera_Forum
Honored Contributor
15 years ago
You may have done that step already but before you start looking at memory bandwidth issues you should probably try whether the following is working to rule out issues with the CVO:

TPG@1600x1200 -> CVO
Altera_Forum
Honored Contributor
15 years ago
--- Quote Start ---
If all configurations are OK, maybe you have memory bandwidth problem?

The frame buffer need to access the memory much more frequently at 1600 x 1200 then in 1280 x 1024.
At 1600 x 1200 x 24bit x 60Hz input & output to the frame buffer you need very high memory bandwidth.

Can you give us the details of the SDRAM (DDR) you are connecting to the FB?

--- Quote End ---

Thanks for the feedback,

Attached please find settings for the SDRAM.

Please let me know if any more info is needed.

Thanks,
Mike
Altera_Forum
Honored Contributor
15 years ago
--- Quote Start ---
You may have done that step already but before you start looking at memory bandwidth issues you should probably try whether the following is working to rule out issues with the CVO:

TPG@1600x1200 -> CVO
--- Quote End ---

Yes, I've tried this, in the following video configuration:

CVI -> SCALER -> FRAMEBUFFER -> CVO

along with following configurations using the above path:

1280x1024 Scaled to 1600x1200: Working.
1024x768 Scaled to 1600x1200: Working.
800x600 Scaled to 1600x1200: Broken!

I think the CVO is ok as I've managed to push pretty much every resolution through without issue.

Thanks,
Mike
Altera_Forum
Honored Contributor
15 years ago
>1280x1024 Scaled to 1600x1200: Working.
>1024x768 Scaled to 1600x1200: Working.
>800x600 Scaled to 1600x1200: Broken!

Sorry, I missed that bit from your first post. This seems to indicate that the issue is not with the frame buffer either since you have successfully buffered 1600x1200 before.
Altera_Forum
Honored Contributor
15 years ago
--- Quote Start ---
>1280x1024 Scaled to 1600x1200: Working.
>1024x768 Scaled to 1600x1200: Working.
>800x600 Scaled to 1600x1200: Broken!

Sorry, I missed that bit from your first post. This seems to indicate that the issue is not with the frame buffer either since you have successfully buffered 1600x1200 before.
--- Quote End ---

Hey no problem, more info:

18,000 pixels for the CVI input FIFO and 1920 pixels for the CVO FIFO (starts at 1919). I'm monitoring overflow and underflow and they seem to be ok when in 800x600 -> 1600x1200 mode.

I'm defintely open to trying anything here as I've been stuck on this problem for over a week now :)
Altera_Forum
Honored Contributor
15 years ago
Hello Mike,
Can you give us more information regarding the Scaler:
The Scaler clock?
The number of bits per component (R, G, B )?
The bus to the Scaler - parallel or serial?

BR,
Altera_Forum
Honored Contributor
15 years ago
--- Quote Start ---
Hello Mike,

Can you give us more information regarding the Scaler:
The Scaler clock?
The number of bits per component (R, G, B )?
The bus to the Scaler - parallel or serial?

BR,

--- Quote End ---

Hi Reuven,

The scaler clock is 200MHz. 24 bit (8 per component RGB ). The bus in/out of the scaler is parallel.

Thanks,
Mike

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scaler problem

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