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Author Topic: ERROR: unsupported JPEG in cmd_loadimage()  (Read 10229 times)

christian

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ERROR: unsupported JPEG in cmd_loadimage()
« on: March 15, 2019, 08:04:09 AM »

Hi,

we are trying to display a jpeg image on a display connected to the BT815. But we got

Quote
ERROR: unsupported JPEG in cmd_loadimage()

followed by multiple

Quote
ERROR: display list overflow

The error message is clear but we can't find a reason why the jpg is not supported. The data sheet says that progressive jpeg is not supported but our jpeg is not progressive.

I attached the unsupported jpeg. What do we need to change to display the jpeg?

« Last Edit: March 15, 2019, 08:07:04 AM by christian »
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Rudolph

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Re: ERROR: unsupported JPEG in cmd_loadimage()
« Reply #1 on: March 15, 2019, 11:47:31 AM »

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christian

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Re: ERROR: unsupported JPEG in cmd_loadimage()
« Reply #2 on: March 18, 2019, 07:58:48 AM »

Hi Rudolph,

Thanks for your response.

We did the open and save again trick with Gimp too and we also tried some jpeg analysis like you did. But we can't find the difference. Unfortunately this jpeg is only one of an ongoing jpeg stream so we can't just save the jpeg again with an external tool to display it. We need to know what we have to change at the stream source.

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christian

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Re: ERROR: unsupported JPEG in cmd_loadimage()
« Reply #3 on: March 18, 2019, 03:28:23 PM »

By analysing the binary my colleagues found that jpegs with one big quantization table won't work. If you open the jpeg and save it again with Gimp (or another image tool) the quantization table will be split up into multiple tables of smaller size. Can anybody confirm this?
   
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Rudolph

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Re: ERROR: unsupported JPEG in cmd_loadimage()
« Reply #4 on: March 23, 2019, 07:45:02 PM »

At least https://29a.ch/photo-forensics/ shows a difference then between the original file and the one I saved with IrfanView.

Original structure:
    SOI
    APP0
    DQT
    SOF0 (Baseline DCT)
    DHT
    DRI
    SOS
    EOI

New structure:
    SOI
    APP0
    DQT
    DQT
    SOF0 (Baseline DCT)
    DHT
    DHT
    DHT
    DHT
    SOS
    EOI

So the new file does not only have two DQT entries but also four DHT entries.
Oh yes, and no DRI entry, whatever a "Define Restart Interval" is good for.
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BRT Community

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Re: ERROR: unsupported JPEG in cmd_loadimage()
« Reply #5 on: April 11, 2019, 09:58:47 AM »

Hello,

The IC designers have confirmed that this is a limitation of the BT815, and can only be resolved in the next iteration of the silicon.

Best Regards,
FTDI Community
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