[FFmpeg-devel] [PATCH RFC] libavdevice/decklink: Add support for EIA-708 output over SDI

Devin Heitmueller dheitmueller at ltnglobal.com
Sat Oct 7 00:21:53 EEST 2017

Hello Carl,

> On Oct 6, 2017, at 5:07 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> 2017-10-06 18:56 GMT+02:00 Devin Heitmueller <dheitmueller at ltnglobal.com>:
>> From: Devin Heitmueller <dheitmueller at kernellabs.com>
>> Hook in libklvanc and use it for output of EIA-708 captions over
>> SDI.  The bulk of this patch is just general support for ancillary
>> data for the Decklink SDI module - the real work for construction
>> of the EIA-708 CDP and VANC line construction is done by libklvanc.
> Nothing except the decklink device could use VANC?

You could absolutely have other SDI device types which can contain VANC.  This was a key reason that we put all the business logic for VANC processing in a separate library.

The goal behind developing libklvanc was to separate out VANC processing from device and application specific business logic.  This allows us to have a single parser and implementation of popular VANC protocols in a single library that can be reused by VLC, OBE, and ffmpeg.  It also allows the VANC processing to be shared across different device types, although admittedly there are not many vendors other than BlackMagic that are very popular.

The point of the remark in the commit message though was to observe that most of the code in the patch implements the decklink specific glue for accessing VANC lines.  The libklvanc library provides all the functions for parsing/generation of the VANC packets.


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