From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue, 24 Feb 2009 00:31:37 +1100
Message-ID: <775b8d190902230531w41cf6724y7a852224806fe1bf@mail.gmail.com>
From: Bruce Ellis <bruce.ellis@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] actionfs
Topicbox-Message-UUID: a616ec92-ead4-11e9-9d60-3106f5b1d025

to make "score" i converted over 30,000 frames from mpg to tiff, using
inferno. it took a while, as it was 10 years ago, but nice to wake up
to.

brucee

On Mon, Feb 23, 2009 at 11:13 AM,  <mattmobile@proweb.co.uk> wrote:
> Hi,
>
> this one was an experiment
>
> /n/sources/contrib/maht/actionfs.c
>
> invoked with a regex like  actionfs (file.mpg).([0-9]+).(ppm)
>
> if you then
>
> cat /n/actionfs/file.mpg.100.ppm
>
> actionfs responds with the output from executing
>
> /bin/action-read $fd file.mpg.100.ppm file.mpg 100 ppm
>
> where $fd will be an fd to write to
>
> i.e. trivially action-read would be something like
>
> ----
> #!/bin/rc
>
> fd =3D $1
> shift
>
> echo $* > /fd/$fd
>
> -----
>
> The coresponding action-write also works
>
>
> ----
> #!/bin/rc
>
> fd =3D $1
> shift
>
> cat /fd/$fd > /dev/null # or whatever
>
> -----
>
> I wrote it specifically to extract individual frames from video files usi=
ng ffmpeg on Linux and
> bring them into Plan9 for processing but generalized the arguments in cas=
e I thought of something
> interesting later.
>
> My first round of experiment went like this
>
> cpu% cat /bin/action-read
> #!/bin/rc
>
> # expect fd fullname videoname frameno
> fname =3D `{echo -n $3 | tr ! '/'}
> {
>        ssh storm single_frame $fname $4
> } > /fd/$1
>
>
> cpu% cat /n/storm/home/maht/bin/single_frame
> #!/usr/local/plan9/bin/rc
>
> # expect filename frameno
>
> timer =3D `{echo $2  | awk ' { printf "%d.%02d\n",  $1/ 25, 4 * ($1 % 25)=
 }'}
> {
>        ffmpeg -i $1 -t 00.001 -ss $timer /tmp/frame_$pid ^_%d.ppm
>        cat /tmp/frame_$pid ^_1.ppm
>        rm -f frame_$pid ^_1.ppm
>        rm -f frame_$pid ^_2.ppm  # stupid ffmpeg outputs 2 frames (someti=
mes)
> }  >[2] /dev/null
>
>
> I was then using imgfs to calculate the average rgb value to look for bla=
ck frames but (unsurprisingly) it was taking too long (4 secs per frame) es=
p. as the Plan9 I was using is in Qemu, cue installing Plan 9 on my termina=
l.
>
> The ffmpeg part on the Linux side (2Ghz Opteron) was taking 1 second on i=
ts own so I have to come up with some sort of look ahead cache which is con=
trary to the idea, I may as well just convert the whole file to ppms at the=
 start! I've not looked if it is I/O or CPU - perhaps a bit of both.
>
> I've not got round to doing it on my fresh terminal yet. I've got a new 3=
.2Ghz Dual Xeon server to migrate to and a Quad Core terminal to play with =
so we'll see how that works out.
>
> I was hoping to get Xcpu in there but I couldn't see how to get the Plan9=
 part working though I have the Linux bits up.
>
> I have a couple of decent OSX boxes available too (one PPC one Intel) but=
 I gave up getting it to compile :)
>
> too many projects .....
>
> matt
>
>