Ancillary data on Quad @ 720p on Linux

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Chuck McCrobie

  • Posts: 3
  • Joined: Wed Mar 26, 2014 4:53 pm

Ancillary data on Quad @ 720p on Linux

PostFri Dec 05, 2014 2:58 pm

I am seeing a strange issue with 720p on Linux with respect to VANC caption data. The caption distribution packet (CDP) contains a sequence counter. We use that sequence counter as one check that the caption data we are receiving is good.

Our caption data occassionally is missing pairs or has "extra" pairs inserted. Corresponding to this, we receive video frames containing CDP's that are out of sequence. The sequence counter would indicate a previously received CDP. The sequence counter is off by 60 frames.

We are using the Decklink Quad card to capture 10-bit UYVY, then extracting the CDP's. We check for the DID/SID (61/01), checksum on the VANC packet, #User data words, CDP identifier (96 69), CDP checksum, and CDP sequence number - all appear okay except for the sequence number being out of sequence. We also grab the frameTime and hardware frame time from the IDeckLinkInputVideoFrame - the timestamps all indicate monotonically increasing frames - i.e. the timestamps do not "jump backwards".

Has anyone else noticed old ancillary data being delievered?

There are, of course, several possibilities:
1. The D/A feeding the card is delievering old CDP's.
2. The Quad card is delivering old CDP's.
3. Our software is somehow decoding old data.

Particulars:
Linux Fedora 20 3.13.10-200.fc20.x86_64
BIOS Information
Vendor: American Megatrends Inc.
Version: F9
Release Date: 09/19/2012
BIOS Revision: 4.6
Base Board Information
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: Z77-DS3H
DesktopVideo: desktopvideo-10.1-a11.x86_64
03:00.0 Multimedia video controller: Blackmagic Design DeckLink SDI/Duo/Quad (Quad card)
KiB Mem: 16323352 total, 14896840 used, 1426512 free, 323804 buffers

Thanks in advance,

Chuck
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Deron Kazmaier

  • Posts: 3
  • Joined: Sat Aug 29, 2015 2:10 pm

Re: Ancillary data on Quad @ 720p on Linux

PostMon Aug 31, 2015 5:20 pm

I can't really help you with this issue, since I am just getting my feet wet in the CC world, but maybe you can help me?

I wrote a Decklink driver for ffmpeg (posted as a patch to the ffmpeg list a few years back) and I'd like to update it to include CC output now that ffmpeg supports 608 decoding. Any chance you could provide me with some VANC caption data packets? Would help immensely in figuring out how the data should be formed.

Thanks,
Deron
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André Ribeiro Camargo

  • Posts: 4
  • Joined: Fri Sep 16, 2016 12:28 am

Re: Ancillary data on Quad @ 720p on Linux

PostWed Sep 21, 2016 7:52 pm

Hello,

I have a DeckLink Studio 4K and I can provide you some Ancillary data to test.

I can extract data using the Capture's sample included in the SDK.

How can we do it?

Best regards
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asperi

  • Posts: 16
  • Joined: Sat Nov 27, 2021 5:59 pm
  • Real Name: Matt Cavis

Re: Ancillary data on Quad @ 720p on Linux

PostMon Jan 03, 2022 3:47 am

Old post but seeing if there was any progress on this? Thanks!

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