[FFmpeg-user] Decklink input buffer overrun

[Deron]

On 9/23/15 1:47 PM, Flávio Pontes wrote:
> Hi,
>
> I need to stream the 2 inputs from a DeckLink Duo card in FHD.
> So far I could compile ffmpeg with decklink support and capture one input
> at a time without problems.
>
> When I try to capture from the 2 inputs I start getting the following
> message repeatedly on both terminals:
> [decklink @ 0x32287e0] Decklink input buffer overrun!
>
> I use these commands in the terminals:
>
> /opt/ffmpeg_build/bin/ffmpeg -f decklink -re -i 'DeckLink SDI (1)@7' -g 90
> -s hd1080 -profile:v baseline -pix_fmt yuv420p -preset veryfast -c:v
> libx264 -b:v 2000k -bufsize 1400k -minrate 2000k -maxrate 2000k -c:a
> libfdk_aac -b:a 96k -threads 4 -f flv rtmp://10.12.20.62/myapp/tvines
>
> /opt/ffmpeg_build/bin/ffmpeg -f decklink -re -i 'DeckLink SDI (2)@7' -g 90
> -s hd1080 -profile:v baseline -pix_fmt yuv420p -preset veryfast -c:v
> libx264 -b:v 2000k -bufsize 1400k -minrate 2000k -maxrate 2000k -c:a
> libfdk_aac -b:a 96k -threads 4 -f flv rtmp://10.12.20.62/myapp/tvescola
>
> I tried many combinations but couldn't get it to work.
> I wonder if the input buffer is shared between the 2 inputs.
> Is there any way to set an input buffer size independently for each command?
>
> Thx in advance!
> Flávio.
>


My first thought was you are simply not keeping up. Are you positive 
your computer can process these two streams at the same time?

I've not tried to capture from a Duo, but I've captured two streams 
simultaneously from a Quad using other software. Since you are running 
two independent copies of ffmpeg, I don't think there is a shared 
internal buffer to increase. Hopefully you will get some more useful 
advice from others.

Deron