[FFmpeg-user] Decklink with ffmpeg audio desync

Reuben Martin reuben.m at gmail.com
Thu May 19 22:38:49 CEST 2016

On May 17, 2016 3:05 AM, "Dpto. Datos Television Costa Blanca" <
datos at tvt-datos.es> wrote:
> El 16/05/2016 a las 22:15, Marton Balint escribió:
>> The problem may well be that when the decklink card loses input, it
>> provides video frames only but no audio. I am afraid you have to dig into
>> the code, to figure out what is really going on. You can try to modify it
>> so it only adds a video frame to its packet queue if audioFrame is not
>> null.

You are not going to fix this without replacing the hardware in front of
the decklink. The matrix switching its input source is doing a hard switch.
It's the equivalent of quickly unplugging and plugging something else in,
so that is going to cause problems. You have to have a matrix switch in
front of it that internally synchronizes the inputs and doesn't interrupt
the signal when switching between them. It may have worked with analog, but
digital is a lot more fragile to interruption.


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