Tag Archives: video

Short talk about NBD from the KVM Forum 2019

Here’s our short talk about Network Block Device (NBD) given at the KVM Forum last month:

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My KVM Forum 2015 talk: New qemu technology used in virt-v2v

All KVM Forum talks can be found here.

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ARM Server Update on Fedora and RHEL

A talk by Jon Masters:

All the Fedora Flock 2014 talks are here: https://www.youtube.com/channel/UCQIXiF6fxPCtHw_XwHFq6nA


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My 10 minute lightning talk on virt-builder from FOSDEM 2014


My 10 minute lightning talk about virt-builder is available to download now (video).

Since there are a few sound problems early on in the talk, I have also created a subtitles file: Advanced_disk_image_management_with_libguestfs.srt With VLC you can just drop this file into the same directory as the video file, and VLC will automatically display the subs. With other players you might need to load the subs separately.

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CentOS Dojo videos online

The Youtube playlist is here. (Sorry, these have been up for a couple of months, but I only spotted them now).


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5 minute introduction to Augeas (config file editing library)

Dominic Cleal’s short introduction to the Augeas configuration API.

We use Augeas a lot in libguestfs and virt-v2v, and it’s been very effective for us.

I asked Dominic how he made this video.

He uses gtk-recordmydesktop, max 100/100 audio/video quality, 30fps, 2 channel audio at 48kHz.

Sound and video are recorded at the same time, with a Sennheiser headset.

Editing is done in kdenlive.

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Feynman “Fun to imagine”

Video series on Youtube. Showing once again that Richard Feynman was a genius and a brilliant communicator.

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libguestfs webinar video — final cut

Here is the video, handout and transcript:


How did I do it in the end? Using ffmpeg on the command line and the editing script from my previous posting.

#!/bin/bash -

set -e

input="libguestfs-20111118 1602-1.mp4"

codec="-b 500k -vcodec libx264 -ab 128k"
codec_novideo="-vn -ab 128k"
codec_noaudio="-b 500k -vcodec libx264"

cd /tmp

# part1: verbatim
# part2: replace video with "network failure" slide
# part3: verbatim
# part4: replace video with slide #5 from handout
# part5: verbatim
# part6: replace video with slide #1 from handout

split () {
    rm -f part1.avi part2_audio.avi part3.avi part4_audio.avi part5.avi part6_audio.avi

    ffmpeg -i "$input" -t 00:11:30 $codec part1.avi

    # end 13:33
    ffmpeg -i "$input" -ss 00:11:30 -t 00:02:03 $codec_novideo part2_audio.avi

    # end 32:03
    ffmpeg -i "$input" -ss 00:20:09 -t 00:11:54 $codec part3.avi

    # end 34:20
    ffmpeg -i "$input" -ss 00:32:03 -t 00:02:17 $codec_novideo part4_audio.avi

    # end 40:46
    ffmpeg -i "$input" -ss 00:34:20 -t 00:06:26 $codec part5.avi

    # end 49:32
    ffmpeg -i "$input" -ss 00:41:55 -t 00:07:37 $codec_novideo part6_audio.avi

static_slides () {
    # to replace part2 video
    rm -f part2_video.avi
    ffmpeg -loop_input -i /tmp/network_failure.png -t 00:02:03 \
        -vf pad='1024:768' -r 8 $codec_noaudio part2_video.avi

    # to replace part4 video
    rm -f part4_video.avi
    ffmpeg -loop_input -i /tmp/slide6.png -t 00:02:17 \
        -vf pad='1024:768:iw/2' -r 8 $codec_noaudio part4_video.avi

    # to replace part6 video
    rm -f part6_video.avi
    ffmpeg -loop_input -i /tmp/slide1.png -t 00:07:37 \
        -vf pad='1024:768:iw/2' -r 8 $codec_noaudio part6_video.avi

combine () {
    # combine audio and video
    rm -f part2.avi
    ffmpeg -i part2_audio.avi -i part2_video.avi $codec part2.avi
    rm -f part4.avi
    ffmpeg -i part4_audio.avi -i part4_video.avi $codec part4.avi
    rm -f part6.avi
    ffmpeg -i part6_audio.avi -i part6_video.avi $codec part6.avi

assemble () {
    rm -f "$output"
    # Concatenate parts into final video.  Note no transcoding here.
    mencoder part{1,2,3,4,5,6}.avi -ovc copy -oac copy -o "$output"


The final video isn’t a fully open format, in that it uses patented (in the US) H.264 and MP3. However it is fully playable with free software, particularly outside the US. The other advantage of using libx264 is it resulted in the smallest file size of all the codecs I tried.

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libguestfs webinar video … and an experiment in open video editing!

After my failure yesterday to find a video editor that doesn’t suck, and because I want to get the libguestfs webinar out as soon as possible, I’m going to take an alternative approach to this.

Here is the unedited video:

http://oirase.annexia.org/tmp/libguestfs-20111118%201602-1.mp4 (13758086 bytes)

And here are my video editing instructions!

11:30-13:30 Because of a network drop, we lost the video during this part, although the sound was fine. This could be left, rerecorded, or replaced with a static slide.
13:30-20:09 Completely cut this section.
32:03-34:20 Replace video with slide #5 from the handout. Leave audio.
40:46-41:55 Cut this section.
41:55-49:32 Replace video with generic slide, eg. slide #1. Leave audio.
49:32-end Cut.

Note the video is straight from webex, untouched, so it’s in a proprietary format (avc1 video, mp4a audio). Most Linux players will play it just fine.

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Video editing … again

Since I forgot how to use Blender, I thought I’d try out a different video editor.

kdenlive. Usability FAIL. You can’t just load a video clip and edit it, unless it fits a “profile”. This video clip is a screen capture at 1024×768 so of course it doesn’t fit any existing profile like HD, DVD, 720p etc.

Why is video editing so hard?


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