Hacking together a FreeBSD

presentation streaming box

For as little as possible

Tom Jones tj@enoti.me

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`whoami`

Internet Engineer
Foolish volunteer
- "I said yes because I don't know how to say no"
Founder, sometime organiser at local hackerspace
- I take the hackerspace camping every summer (campgnd.com)
Organiser of Techmeetup Aberdeen
- Monthly event with beer, pizza and talks

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When will the talks be up?

"What is needed is adding logos to the front of the video and uploading them to YouTube. That takes time and effort."

"Video is not high priority. It is a volunteer effort done only because folks want it. There is so much work and effort put into the the conference in the months before the conference, that once it is over, we want to attend to so many other tasks which have been pushed to the side. We need to get caught up on our personal lives. This is part of why it takes so long to get post-conference tasks completed."

Dan Langille

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Why this talk?

Recording talks is easy
- uploading them is nigh on impossible
Streaming
- expensive
- hard
- require multiple people to operate
- physically exhausting and emotionally devastating
If we can can make the equipment cheap the event can own it
If the event owns the equipment they can train a team

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What this talk is

Architecture, tools and equipment to stream events
Technical explanation of what these pieces do
Instructions on how to hack these pieces together
Tools to debug

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Typical Box6 / 68

Iron Age Smelting

Smelt

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ERG Summer School

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ERG Summer School

- Projector                                
- Capture Devices
    - Audio                             £ 200 + (microphones)
    - Video                             £1600
- Mixing                                £1699
    - Combine multiple video sources
    - Combine multiple audio sources
    - Combine audio and video
- Uplink laptop                         £1000
Total                                   £4499

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ERG Summer School

Coffeepot Cam

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Summer School Architecture

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What are we doing right now?My laptop is connected to this projector, you can see my slides
I am standing up here talking
You are listening to me (I hope) and watching stuff from my laptop

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Ideally we would share this experience far beyond this room
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Requirements

Capture the output from the laptop
Capture the audio from speaker

Send our capture to the internet
Distribute it as far as possible

The Solution

Self contained
Plug and play

Cheap enough for the event to own it
- Less that £100 would be ideal

Components MUST be generally for sale
Run FreeBSD

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What we don't getVideo of the speaker
Audience participation (repeat the question!)
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Components

Capturing Slides
Capturing Audio
Mixing
Streaming Out
Recording Video

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Capturing SlidesScreen Capture software
HDMI Capture Card
Hacked up HDMI thing
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Capturing SlidesScreen Capture software
HDMI Capture Card
Hacked up HDMI thing
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Capturing Slides

~~Screen Capture software~~
HDMI Capture Card

Hacked up HDMI thing

Magic Smoke

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Capturing SlidesScreen Capture software
HDMI Capture Card
Hacked up HDMI thing
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HDMI Ethernet Extender

NOT 60m HDMI CAT6 Ethernet extenders
LKV373 based HDMI Ethernet extender

HDMI Range Extender Orders

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HDMI Ethernet Extender

NOT 60m HDMI CAT6 Ethernet extenders
LKV373 based HDMI Ethernet extender

CAT6 Extender Glitch

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HDMI Ethernet Extender

LKV373 HDMI Extender
MPEG2 Multicast
Fully reverse engineered [1]

HDMI Range Extender

1: https://blog.danman.eu/new-version-of-lenkeng-hdmi-over-ip-extender-lkv373a/

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HDMI Ethernet Extender

# tcpdump -i ue0 
17:00:28.285648 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.285902 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.286156 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.286410 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.286664 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.286918 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.287172 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.287426 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 1316
17:00:28.288095 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0
17:00:28.289093 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0
17:00:28.290093 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0
17:00:28.291093 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0
17:00:28.292094 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0
17:00:28.293093 IP 192.168.1.238.5004 > 239.255.42.42.5004: UDP, length 0

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HDMI Ethernet Extender

HDMI Range Extender Wireshark

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HDMI Ethernet Extender

# ifconfig ue0 192.168.1.2/24
$ cvlc udp://@239.255.42.42:5004

HDMI Check signal

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Bridging multicast to unicast

bridge.sh

#!/bin/sh  
socat UDP4-RECV:5004,ip-add-membership=239.255.42.42:192.168.1.2 STDOUT | nc -u 192.168.1.2 5000
$ cvlc udp://@:5000
$ bridge.sh

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Components

Capturing Slides
Capturing Audio
Mixing
Streaming Out
Recording Video

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Capturing AudioInterfacesUSB Desk ($$)
USB Interface ($)
Built-in Audio Interface (0)
MicrophonesLavalier
Cardioid
Boundary/Area
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Capturing Audio

USB Audio

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Capturing Audio

Microphone

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Capturing Audio

sox is netcat for audio
check your levels:

$ rec -n
Input File     : 'default' (coreaudio)
Channels       : 2
Sample Rate    : 44100
Precision      : 32-bit
Sample Encoding: 32-bit Signed Integer PCM
In:0.00% 00:00:11.96 [00:00:00.00] Out:526k  [ -====|====- ]        Clip:6

Record and play back

$ rec -c 1 test.wav
$ play test.wav

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Check that time is progressing at the correct rate

$ man 4 snd_uaudio
...
BUGS
... 
  Some USB audio devices might refuse to work properly unless the sample
  rate is configured the same for both recording and playback, even if only
  simplex is used.  See the dev.pcm.%d.[play|rec].vchanrate sysctls.
  The PCM framework in FreeBSD currently doesn't support the full set of
  USB audio mixer controls.  Some mixer controls are only available as
  dev.pcm.%d.mixer sysctls.

If your test is fast or slow you may need to manually sync the rate

 $ sudo sysctl dev.pcm.4.rec.vchanrate=44100
 dev.pcm.4.rec.vchanrate: 48000 -> 44100

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Aside: Software Defined Radio

A wireless lavalier mic made the most sense
It says 229.7M on it
could we just grab it from the air?

Wireless mic frequency

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Aside: Software Defined Radio

RTLSDR

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Aside: Software Defined Radio35 / 68

Aside: Software Defined Radio36 / 68

Aside: Software Defined RadioAM Voice
229.7MHz center freq
~15KHz wide
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Playing audio with rtl_sdr

Test SDR with FM radio

$ rtl_fm -M wbfm -f 97.5M | \
    play -r 32k -t raw -e s -b 16 -c 1 -V1 -

Capturing the wireless mic with rtl_sdr

$ rtl_fm -M am -f 229.7M -s 15k -E swagc | \
    play -r 15k -t raw -e s -b 16 -c 1 -V1 -

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Components

Capturing Slides
Capturing Audio
Mixing
Streaming Out
Recording Video

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Mixing: gstreamer

Everything assemblerizer for video and audio

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Mixing: gstreamer audio

$ gst-launch-1.0 audiotestsrc ! autoaudiosink

BEEEEEEEEEEEP!

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Mixing: gstreamer video

$ gst-launch-1.0 videotestsrc ! autovideosink

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Mixing: gstreamer video

Video Test SRC

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Mixing: gstreamer muxing

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Mixing: gstreamer demuxing

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Playing video from the feed

recvfeed.sh

gst-launch-1.0 \
    udpsrc port=5000 \
    ! tsdemux \
    ! queue \
    ! h264parse \
    ! avdec_h264 \
    ! autovideosink

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Playing Audio

gst-launch-1.0 \
    autoaudiosrc \
    ! autoaudiosink

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Components

Capturing Slides
Capturing Audio
Mixing
Streaming Out
Recording Video

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Streaming Out

Streaming Service handles:
- Ingestion (accepting our feed)
- Distribution
- Recording
- Fan out
Scale Engine
- FreeBSD Streaming CDN
- Free streaming for BSD events (ask Allan)
- Other streaming services are available

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Streaming OutService accepts a Real-Time Messaging Protocol (RTMP) stream 
RTMP TCP protocol on port 1935
H264 Video
AAC Audio

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Streaming box

x5 box

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Streaming out

Mux it together

    flvmux name=muxer streamable=true \
    ! rtmpsink location='rtmp://example-origin.secdn.net/example-origin/live/419fw' \

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Streaming out

Audio

    autoaudiosrc \
    ! audioconvert \
    ! wavenc \
    ! wavparse \
    ! audioconvert ! audioresample \
    ! audio/x-raw, rate=48000 \
    ! avenc_aac \
    ! muxer. \

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Streaming out

Video

    udpsrc port=5000 \
    ! tsdemux \
    ! queue \
    ! h264parse \
    ! muxer.

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Streaming out

In full we get stream.sh

gst-launch-1.0 -e \
    flvmux name=muxer streamable=true \
    ! rtmpsink location='rtmp://example-origin.secdn.net/example-origin/live/419fw' \
    autoaudiosrc \
    ! audioconvert \
    ! wavenc \
    ! wavparse \
    ! audioconvert ! audioresample \
    ! audio/x-raw, rate=48000 \
    ! avenc_aac \
    ! muxer. \
    udpsrc port=5000 \
    ! tsdemux \
    ! queue \
    ! h264parse \
    ! muxer.

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Components

Capturing Slides
Capturing Audio
Mixing
Streaming Out
Recording Video

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RecordingScale Engine defaults:Start a recording at rtmp publish
Stop recording at rtmp unpublish

Recordings recoverable from Scale Engine file store
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Pulling it all together

Lantap

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Pulling it all together

All together

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Pulling it all together

Tidy setup

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Architecture

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Using itFind scaleengine dashboard demo feed
Launch stream.sh
Launch bridge.sh
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Final System

- LKV373 HDMI Extender Pair £ 61.99
- Lavalier mic              £ 10.98
- Lantap                    £ 11.52
- USB Ethernet Nic          £ 12.99
- USB Audio                 £  6.49
                            =======
Total                       £103.97
- x5-z8350 PC               £ 72.99
- Whole bunch of cables     £ ??.??

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Thank you for listeningQuestions?64 / 68

Colophon

This presentation is open source software and was made with open source software. Open tools were used to build the system presented and the final system is open source.

FreeBSD
wireshark
gstreamer
socat
sox
vim
remark.js
goat
firefox

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Saving the video feed to a file

recordfeed.sh

gst-launch-1.0 \
    udpsrc port=5000 \
    ! tsdemux \
    ! queue \
    ! h264parse \ 
    ! mp4mux \
    ! filesink location=test.mp4

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Capturing AAC Audio

gstreamer audio pipeline

gst-launch-1.0 \
    autoaudiosrc \
    ! audioconvert \
    ! wavenc \
    ! wavparse \
    ! audioconvert ! audioresample \
    ! audio/x-raw, rate=48000 \
    ! avenc_aac \
    ! filesink location=output.mp4

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Feeding the rtlsdr into gstreamer

$ rtl_fm -M am -f 229.7M -s 15k -l 150 -E swagc | \
    gst-launch-1.0 fdsrc \
    ! audio/x-raw, format=S16E, channels=1, layout=interleaved, rate=15000 \
    ! autoaudiosink

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Hacking together a FreeBSD

presentation streaming box

For as little as possible

whoami

When will the talks be up?

Why this talk?

What this talk is

Typical Box

Iron Age Smelting

ERG Summer School

ERG Summer School

ERG Summer School

Summer School Architecture

What are we doing right now?

Requirements

The Solution

What we don't get

Components

Capturing Slides

Capturing Slides

Capturing Slides

Capturing Slides

HDMI Ethernet Extender

HDMI Ethernet Extender

HDMI Ethernet Extender

HDMI Ethernet Extender

HDMI Ethernet Extender

HDMI Ethernet Extender

Bridging multicast to unicast

Components

Capturing Audio

Interfaces

Microphones

Capturing Audio

Capturing Audio

Capturing Audio

Record and play back

Check that time is progressing at the correct rate

Aside: Software Defined Radio

Aside: Software Defined Radio

Aside: Software Defined Radio

Aside: Software Defined Radio

Aside: Software Defined Radio

Playing audio with rtl_sdr

Test SDR with FM radio

Capturing the wireless mic with rtl_sdr

Components

Mixing: gstreamer

Mixing: gstreamer audio

Mixing: gstreamer video

Mixing: gstreamer video

Mixing: gstreamer muxing

Mixing: gstreamer demuxing

Playing video from the feed

Playing Audio

Components

Streaming Out

Streaming Out

Streaming box

Streaming out

Streaming out

Streaming out

Streaming out

Components

Recording

Pulling it all together

Pulling it all together

Pulling it all together

Architecture

Using it

Final System

Thank you for listening

Questions?

Colophon

Saving the video feed to a file

Capturing AAC Audio

Feeding the rtlsdr into gstreamer

whoami

Help

`whoami`

`whoami`