[GEM-dev] [ pd-gem-Feature Requests-1901418 ] pix_write to a PPM stream

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Fri Sep 24 04:20:15 CEST 2010

Feature Requests item #1901418, was opened at 2008-02-25 14:46
Message generated for change (Settings changed) made by sf-robot
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Category: None
Group: None
>Status: Closed
Priority: 5
Private: No
Submitted By: ClaudiusMaximus (claudiusmaximus)
Assigned to: Nobody/Anonymous (nobody)
Summary: pix_write to a PPM stream

Initial Comment:
I would very much like if pix_write could write successive frames to a PPM stream.  This would let me to do things like:

mkfifo stream.ppm &&
pd -nogui -lib Gem -open my-rendering-patch.pd &
cat stream.ppm |
ppmtoy4m ... |
y4mscaler ... |
mpeg2enc ...

At the moment I'm rendering to multiple TIFF files, which takes a vast amount of temporary disk space, and is more complicated to encode later.


>Comment By: SourceForge Robot (sf-robot)
Date: 2010-09-24 02:20

This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).


Comment By: Nobody/Anonymous (nobody)
Date: 2010-07-14 18:46

for writing to a PPM stream, you can already do [#from_pix, cast b] and
then [#out ppm mypipe.ppm]. why require a GEM-only solution ?

btw I don't understand what v4l1-loopback has to do with the question.


Comment By: IOhannes m zmlnig (zmoelnig)
Date: 2010-07-14 17:48

i have added an experimental support for writing to v4l1-loopback devices
to the [pix_record] class.
unfortunately, [pix_record] (and the record-backends) are badly designed
right now, i guess they need a major overhaul.

in the meantime: 
- install vloopback kernel-module
- get latest Gem (svn) 
- build, cd to src/plugins/recordV4L/ and run "autoreconf -fiv &&
./configure && make"
- copy the resulting ./libs/gem_recordV4L.so besides the Gem.pd_linux 
- make sure you have no other gem_record* lying besides Gem.pd_linux
- start pd/Gem 
- create [pix_record]
- use [file /dev/video1, record 1( (or whatever your vloopback-write
device is)

- then you should be able to access the output of pix_record via


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