Re: [9fans] actionfs

[Bruce Ellis <bruce.ellis@gmail.com>]

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 = $1
> shift
>
> echo $* > /fd/$fd
>
> -----
>
> The coresponding action-write also works
>
>
> ----
> #!/bin/rc
>
> fd = $1
> shift
>
> cat /fd/$fd > /dev/null # or whatever
>
> -----
>
> I wrote it specifically to extract individual frames from video files using ffmpeg on Linux and
> bring them into Plan9 for processing but generalized the arguments in case 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 = `{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 = `{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 (sometimes)
> }  >[2] /dev/null
>
>
> I was then using imgfs to calculate the average rgb value to look for black frames but (unsurprisingly) it was taking too long (4 secs per frame) esp. as the Plan9 I was using is in Qemu, cue installing Plan 9 on my terminal.
>
> The ffmpeg part on the Linux side (2Ghz Opteron) was taking 1 second on its own so I have to come up with some sort of look ahead cache which is contrary 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
>
>