BATC Forum

While searching YouTube I found this video.

It looks like a easy to hack cheap MPEG4 to TS encoder for $40
From the video it also looks like you can change the encoding bitrate from the hidden GUI.

https://www.youtube.com/watch?v=SAvGylthpkU

Here is the associated blog

https://blog.danman.eu/new-version-of-l ... r-lkv373a/

Seems like some versions of it use TS and others use RTP

- Charles

Could this be used to remote stream to batc.tv repeater or private stream?
Looks interesting.

I don't know. It just looks like a cheap HDMI capture device.
I have a couple on order from China so will report back after I get them.

- Charles

I thought that it looked very interesting for enabling HD transmissions from my HDMI camera using DATV Express or Portsdown. I've ordered one as well. £28.99 inc postage (by the slow boat). No promises about future capability though!

Dave

This does look interesting. From the embedded youtube blog above, protocol is HDbitT (http://www.hdbitt.org/what-is-hdbitt.html)

Was given an older IP to HDMI RX which has a TF-680 SOC (http://www.jlink.com.tw/tw/pro_list02.h ... del_id=145). SOC appears to use MJPEG for lower latency then H.264.

Am assuming that H.264/IEC13818 has latency issues since you have to wait some indeterminate amount of time for an anchor-frame before you can start re-stitching the whole mess back together again.

It is well worth reading through the whole of the blog, and watching the whole video that Charles linked to, there is clearly some interesting stuff going on.

If some brave soul prises the heat sinks off one of the newer units, would be very interested to see what could be found about them.

... and for those who like interesting documents, take a look at docin.com. Haven't figured how to set up an account yet, but it looks like quite a resource.

-Mark

danman has confirmed that you can load an older version of the firmeware
onto the device to get Transport Stream support. described in Update 14. dec
on his blog.

- Charles

Well I finally got my HDMI adapter from China and with a change of the firmware
I have managed to get it to send a UDP Transport stream, the lowest bitrate it
will operate at is 100 Kbit/s MPEG4. The audio is fixed at 192Kbits. It can also
downscale an FHD 1920x1080 (1090) picture to SD.

The PIDS appear fixed and there are a load of zero length UDP packets sent
in the stream, so a bit of software will be needed to extract those and to
remove the SI tables and change the PIDs (the Linux GUI version of Express has that
facility already to deal with Hauppauge HD capture devices).

I have not been able to get it to stream into vMix as VMix objects to the
IP port address of 5004 and I can't find a way to change it.

There is about 1.5 secs delay on the video. The picture quality looks pretty good from my
camcorder.

So far so good.

- Charles

Fascinating
Is there any point in the circuit that one could tap off a parallel data stream do you know?
73
Laurence M0LDZ AKA 2E0DTX

No I don't know but the reference to all this is danmans site https://blog.danman.eu/new-version-of-l ... r-lkv373a/

If you are after an MPEG4 encode chip try talking to Jun Wang wchsing225@gmail.com of VATek

- Charles

Hello Charles and Dave,

VK5YYY brought on of these devices and it arrived yesterday, as of yet I have not done any modifications to it, which may be necessary, however I was able to use it with the Portsdown software with a couple of modifications, the resultant video and sound are not usable for broadcast yet, but cant be too far from being usable as a HDMI input for the Raspberry PI and the Portsdown project.

The changes I had to make were to the a.sh code, I choose to use the IPTSIN function

# *********************************** TRANSPORT STREAM INPUT THROUGH IP ******************************************
"IPTSIN")
case "$MODE_OUTPUT" in
"BATC")
sudo nice -n -30 $PATHRPI"/ffmpeg" -loglevel $MODE_DEBUG -i videots -y $OUTPUT_BATC & ;;
"DATVEXPRESS")
nice -n -30 nc -u -4 127.0.0.1 1314 < videots & ;;
*)
sudo $PATHRPI"/rpidatv" -i videots -s $SYMBOLRATE_K -c $FECNUM"/"$FECDEN -f $FREQUENCY_OUT -p $GAIN -m $MODE -x $PIN_I -y $PIN_Q &;;
esac

PORT=10000
# $PATHRPI"/mnc" -l -i eth0 -p $PORT $UDPINADDR > videots &
$PATHRPI"/mnc" -l -i eth0 -p 5004 239.255.42.42 > videots &
# Unclear why Evariste uses multicast address here - my BT router dislikes routing multicast intensely so
# I have changed it to just listen on the predefined port number for a UDP stream
# netcat -u -4 -l $PORT > videots &
;;

That was the simplified version, I did originally change PORT=5004 and edit udpinaddr=239.255.42.42 in the rpidatvconfig.txt file after enabling the MNC line but then I download the latest version and for quickness just cut and past the line I needed to get it working.

The netcat function didn't seem to see the multicast stream from the HDMI to IP converter but I plan on doing some more testing today, maybe even trying to get FFMPEG to receive the stream.

73
Bevan
vk5bd