[FFmpeg-user] Decklink with ffmpeg audio desync

[Dpto. Datos Television Costa Blanca]

Hello everyone,

Im Daniel and Im new to the list.

Im doing an mpeg2 ts over multicast with a Decklink SDI 4K as input.
After some random time, audio and video start desyncing. Its start just 
a little bit at first for desyn start growing over time..

This is the command Im using and the initial output.

./ffmpeg -re -f decklink -i "DeckLink SDI 4K at 2" -c:v mpeg2video -pix_fmt 
yuv420p -aspect 16:9 -deinterlace -sc_threshold 1000000000 -b:v 3.5M 
-minrate:v 3.5M -maxrate:v 3.5M -bufsize:v 2.4M -acodec mp2 -ac 2 -b:a 
128k -ar 44100 -af aresample=async=1:min_hard_comp=0.100:first_pts=0 
-metadata service_name="TVT" -mpegts_service_id 123 -f mpegts 
udp://224.0.0.247:5001?pkt_size=1316


ffmpeg version 3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
   built with gcc 4.7 (Debian 4.7.2-5)
   configuration: --enable-gpl --enable-libx264 --enable-libmp3lame 
--enable-decklink --extra-cflags=-I/home/cor/DeckLink/Linux/include 
--extra-ldflags=-L/home/cor/DeckLink/Linux/include/
   libavutil      55. 17.103 / 55. 17.103
   libavcodec     57. 24.102 / 57. 24.102
   libavformat    57. 25.100 / 57. 25.100
   libavdevice    57.  0.101 / 57.  0.101
   libavfilter     6. 31.100 /  6. 31.100
   libswscale      4.  0.100 /  4.  0.100
   libswresample   2.  0.101 /  2.  0.101
   libpostproc    54.  0.100 / 54.  0.100
[decklink @ 0x32d1780] Found Decklink mode 720 x 576 with rate 25.00(i)
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, decklink, from 'DeckLink SDI 4K at 2':
   Duration: N/A, start: 0.000000, bitrate: 1536 kb/s
     Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
     Stream #0:1: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x576, 
-4 kb/s, 25 tbr, 1000k tbn, 25 tbc
Output #0, mpegts, to 'udp://224.0.0.247:5001?pkt_size=1316':
   Metadata:
     service_name    : TVT
     encoder         : Lavf57.25.100
     Stream #0:0: Video: mpeg2video (Main), yuv420p, 720x576 [SAR 64:45 
DAR 16:9], q=2-31, 3500 kb/s, 25 fps, 90k tbn, 25 tbc
     Metadata:
       encoder         : Lavc57.24.102 mpeg2video
     Side data:
       unknown side data type 10 (24 bytes)
     Stream #0:1: Audio: mp2, 44100 Hz, stereo, s16, 128 kb/s
     Metadata:
       encoder         : Lavc57.24.102 mp2
Stream mapping:
   Stream #0:1 -> #0:0 (rawvideo (native) -> mpeg2video (native))
   Stream #0:0 -> #0:1 (pcm_s16le (native) -> mp2 (native))
Press [q] to stop, [?] for help

Any though in what can be causing the descync and how to fix it?

Thanks in advance.

--Daniel B.