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Noisy frames from ADV7611


We are using ADV7611 in our board and connected it to i.MX6UL processor.

We are using laptops and mobile phones as a HDMI source.

The ADV7611 is configured with the recommended settings and we are capturing the frames of different sizes like 640x480, 720x480, 1280x720.

We observed that when iPhone is used as a HDMI source then some of the captured frames are noisy as shown in the image below. When laptop is used as a HDMI source then all captured frames are proper. Can anyone help us identifying the root cause?

Noisy frameCorrect frame

  • This looks like a HDCP authenticate issue between the iPhone and the ADV7611.  When not authenticated the iPhone appears to continue sending encrypted video which would look like this.  Normally sources will not send video until authentication is complete.

  • Hi GuenterL,

    Thanks for quick response.

    The corrupted frames are captured randomly. I mean after initialization 10 20 frames are captured properly and then suddenly a single corrupted frame is captured. Then again it starts capturing the proper frames. Is this a expected behavior if there is HDCP authentication issue?

    Note that our application does not require a continuous streaming. Normal ADV7611 remains in power down mode (setting POWER_DOWN bit in IO register 0x0C). When required it is powered up, frame is captured and again put in the power down state.

    We have been using iPhone since 1-2 years but we observed this issue recently. Can it be related to iOS version? HW is not modified.

    Can it be a power related issue?

  • I do not know anything about iOS.  Can you try an older version (previously version) to see if the problem still exist.

    The image to me looks the 7611 is receiving the image with the wrong or no HDCP key.  Basically you are viewing encrypted data.

    Note that HDCP can take several 100 Milliseconds to authenticate.  During this time the source can send unencrypted video and then start sending encrypted video of which the first frame might not be decrypted properly.

    The correct for sources that require HDCP it to not transmit or transmit blanks until HDCP is authenticated.

    I would not start capturing until HDCP has been authenticated.