[vdr] IPTV plugin stuttering when decoding ATSC streams with VDR to convert ac-3 to mp3 on the fly

[Rob Davis]

I have VDR working in the US with ATSC.  Previously I had it working in
Europe on Satellite.  With VDR I have several Hauppauge VOMP boxes which
act as remote front ends.  Unfortunetely these do not work with AC-3
audio.  Using streamdev and iptv plugins with ffmpeg I want to reencode
the ATSC streams to extra channels in VDR in order to watch them on the
vomp boxes.

I have this almost working.  I can see something on the TV but I get
quite a lot of stuttering and breakup of the picture.  Audio seems to
work, in that I don't get popping.  What am I missing?

When the channel is selected, the IPTV plugin calls a script which
streams from streamdev the TS stream (using mplayer -dumpstream) which
uses a fifo to pipe this into ffmpeg, which writes it to udp, where VDR
picks it up again.

The exciting bits of the script are:

mkfifo $fifo
mplayer $mplayeropts -cache 8192 "$URL" -dumpstream -dumpfile $fifo
>>${LOG} &
MPID=${!}

ffmpeg.streamdev -v 1 \
         -i $fifo -debug 0 \
          -f mpegts -vcodec copy \
          -acodec ${ACODEC} -ac 2 -ab ${ABITRATE}k -ar 48000 -async $fr \
          "udp://127.0.0.1:${PORT}?pkt_size=16356" &


acodec is mp2
abitrate is 192
fr is 29
fifo is dynamically creates
url is http://myserver:3000/TS/103+1