From: Ben Hutchings Date: Tue, 28 Dec 2010 22:10:22 +0000 (+0000) Subject: Early outline of the talk X-Git-Url: https://git.decadent.org.uk/gitweb/?p=lca-dvswitch.git;a=commitdiff_plain;h=a45ddfd4426085bbe33df1129a34a78e9c4e2a32 Early outline of the talk --- a45ddfd4426085bbe33df1129a34a78e9c4e2a32 diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..b6b835b --- /dev/null +++ b/Makefile @@ -0,0 +1,18 @@ +all: s5-checksums.txt dvswitch-simple.svg screenshot-1-annotated.png + +clean: + rm -r s5-checksums.txt s5-blank dvswitch-simple.svg screenshot-1-annotated.png + +s5-checksums.txt: /usr/share/s5/s5-blank + s5 blank . + sed -i 's/url(bodybg.gif)//' s5-blank/ui/default/pretty.css + +%.svg: %.dia + dia --export=$@ $< + +%.png: %.xcf + gimp -i -d -b ' '\ +'(let* ((image (car (gimp-file-load RUN-NONINTERACTIVE "$<" "$<"))) '\ +' (layer (car (gimp-image-flatten image)))) '\ +' (gimp-file-save RUN-NONINTERACTIVE image layer "$@" "$@")) '\ +'(gimp-quit 0)' diff --git a/dvswitch-simple.dia b/dvswitch-simple.dia new file mode 100644 index 0000000..d47a2e5 Binary files /dev/null and b/dvswitch-simple.dia differ diff --git a/index.html b/index.html new file mode 100644 index 0000000..3c5d0a7 --- /dev/null +++ b/index.html @@ -0,0 +1,219 @@ + + + + + +DVswitch - Ben Hutchings - LCA2011 + + + + + + + + + + + + + + + + + +
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DVswitch

+

Ben Hutchings

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+ + +
+

What is DVswitch?

+
    +
  • + A software system that supports video mixing, recording and streaming +
    • +
  • + Designed particularly for the needs of technical conferences that + want to record and stream on a limited budget. Now used more + widely, often without streaming. +
    • +
  • + Mixing is live - a requirement for streaming, and a way to + avoid the need for extensive editing after the event +
    • +
  • + Mixing is interactive - a requirement for good coverage of + presenters, audience and slides, but very limited in other + streaming software +
    • +
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+ +
+

What is DVswitch not?

+

+ There are limited developer resources and limited goals for + DVswitch. It is never intended to be: +

+
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  • + A general video editor +
    • +
  • + An audio mixer (but it does implement audio dubbing and level monitoring) +
    • +
  • + A complete recording and publishing system +
    • +
+

+ These are all better handled by other software and + hardware. +

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+

The 'DV' in DVswitch

+

+ The name refers to the DV formats used by many video cameras: +

+ + + + + + + + + + + + + + + + + + + + + + +
ProfileSpecificationVideo codecSupported
Basic DVIEC 61834DV 25yes
DVCAMSony proprietaryDV 25probably
DVCPROSMPTE 314MDV 25probably
DVCPRO50SMPTE 314MDV 50not yet
DVCPRO HDSMPTE 370MDV 100not yet
HDVIEC 61834MPEG-2no
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+ DV video codecs compress each frame separately (unlike MPEG) +

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+ The lack of interframe compression means there is relatively + little delay between camera and mixer and we can cut between + sources without having to decode all sources all the time. + In fact, DVswitch doesn't need to decode even a single source at + full frame rate if you just cut between sources without using + mixing effects. +

+

+ Unfortunately, most of today's consumer cameras don't have DV + output and may not provide live video output at all. +

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+

Overview of the system

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+ A simplified view of the typical components: +

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Sources

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  • + Source types: firewire/USB DV device, ALSA capture device, + DIF file +
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  • + Physical sources are spread around room and connected to the + mixer via TCP/IP networking +
    • +
  • + Original protocol: mixer runs a network server; sources run as + clients and send DIF over TCP +
      +
    • + Requires a script to coordinate mixer and source startup - + an annoying complication +
      • +
    • + Improvement: tally lights +
      • +
    +
  • + Next release: sources run as RTP/RTSP servers and mixer + connects to them as a client +
      +
    • + No custom scripts required; just configuration files +
      • +
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    • +
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Sinks

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  • + Sink types: DIF files, pipe to arbitrary command +
    • +
  • + Also connected using TCP/IP networking, though this is not such + a good idea for recording +
    • +
  • + Original protocol: mixer runs a network server; sinks run + as clients and receive DIF over TCP +
      +
    • + Improvement: sink reports whether it will record; mixer can + start, stop and cut recording +
      • +
    +
    • +
  • + Next release: file and pipe sinks built into mixer along with an + RTP/RTSP server +
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Mixer

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Mixer

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+ + + diff --git a/screenshot-1-annotated.xcf b/screenshot-1-annotated.xcf new file mode 100644 index 0000000..e667ade Binary files /dev/null and b/screenshot-1-annotated.xcf differ diff --git a/screenshot-1.png b/screenshot-1.png new file mode 100644 index 0000000..a04de74 Binary files /dev/null and b/screenshot-1.png differ