[FFmpeg-user] 608/ 708 Closed Captions output with ffmpeg and Decklink

Matt C asperi at hotmail.com
Tue Jan 4 16:43:43 EET 2022

Looking closer I see your note on pix_fmt, I will try with yuv422p10

ffmpeg -i /home/matt/VideoTests/1080i_TS_SampleFileCC.mpg-pix_fmt -ar:a 48000 yuv422p10 -s 1920x1080 -r 30000/1001 -f decklink -a53cc 0 -map 0 -vcodec v210 "DeckLink SDI 4K"

From: Matt C <asperi at hotmail.com>
Sent: Tuesday, January 4, 2022 2:34 PM
To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
Subject: Re: [FFmpeg-user] 608/ 708 Closed Captions output with ffmpeg and Decklink

Thanks Devin!  I will recompile with libklvanc but I am a bit new at compiling, I have been going off of this guide-

Would I just add-

sudo apt-get update -qq && sudo apt-get -y install \
  autoconf \
  automake \
  build-essential \
  cmake \
  git-core \
  libass-dev \
  libfreetype6-dev \
  libtool \
  libvorbis-dev \
  libklvanc \
  pkg-config \
  texinfo \
  wget \
sudo apt-get -y install \
  nasm yasm libx264-dev libx265-dev libnuma-dev libvpx-dev \
  libfdk-aac-dev libmp3lame-dev libopus-dev


cd ~/ffmpeg_sources
wget https://ffmpeg.org/releases/ffmpeg-4.1.3.tar.bz2
tar -xvf ffmpeg-*.tar.bz2
cd ffmpeg-*/
PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure \
  --prefix="$HOME/ffmpeg_build" \
  --pkg-config-flags="--static" \
  --extra-cflags="-I$HOME/ffmpeg_build/include -I$HOME/ffmpeg_sources/BMD_SDK/include" \
  --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
  --extra-libs="-lpthread -lm" \
  --bindir="$HOME/bin" \
  --enable-gpl \
  --enable-libass \
  --enable-libfdk-aac \
  --enable-libfreetype \
  --enable-libmp3lame \
  --enable-libopus \
  --enable-libvorbis \
  --enable-libvpx \
  --enable-libx264 \
  --enable-libx265 \
  --enable-nonfree \
  --enable-libklvanc \​

I have been running these lines, both play fine but I think I am a little confused on defining the file and defining the output..  Maybe I should be defining the output to be the same as the file type?

ffmpeg -i /home/matt/VideoTests/720ts_6DK01H_tru720og.ts -ar:a 48000 -pix_fmt yuv422p -f decklink -s 1280x720 -r 60000/1001 -a53cc 1 -map 0 -vcodec v210 "DeckLink SDI 4K"

ffmpeg -i /home/matt/VideoTests/720ts_6DK01H_tru720og.ts -ar:a 48000 -s 1280x720 -r 60000/1001 -pix_fmt yuv422p -f decklink -a53cc 1 -map 0 -vcodec v210 "DeckLink SDI 4K"

Thanks for your help and happy new year!

From: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> on behalf of Devin Heitmueller <devin.heitmueller at ltnglobal.com>
Sent: Monday, January 3, 2022 9:48 PM
To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
Subject: Re: [FFmpeg-user] 608/ 708 Closed Captions output with ffmpeg and Decklink

On Mon, Jan 3, 2022 at 3:00 PM Matt C <asperi at hotmail.com> wrote:

> Have tried these lines, they all play fine out the SDI but no captions show:

I haven't tried your actual files, but there are two likely issues here:

1.  Your ffmpeg build needs to be compiled to make use of the
libklvanc library.  That is necessary to produce the SDI VANC data
that makes up the CEA-708 captions.


2.  You must use the v210 codec.  If you use "-pix_fmt uyvy422" that
puts the decklink output into 8-bit mode, which won't work with 10-bit
VANC (as required for CEA-708).



Devin Heitmueller, Senior Software Engineer
LTN Global Communications
o: +1 (301) 363-1001
w: https://ltnglobal.com  e: devin.heitmueller at ltnglobal.com
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