[gst-devel] Firewire cameras with DirectShow

Julien Isorce julien.isorce at gmail.com
Thu Jun 25 20:42:10 CEST 2009

2009/6/25 Phil Rendell <philrendell at gmail.com>

> Thanks. That explains why the two plugins can't speak to each other. I do
> have ffdec_dvvideo, but I can't get gst-launch-0.10 dshowvideosrc ! fakesink
> to work as this causes gst-launch to crash, again without anything useful
> being outputted on the command line, even with the -v option. If I recreate
> the pipeline in my application I get an integer division by zero exception
> sometime during the call to gst_element_link_many.
> I know that dshowvideosrc can find the camera because when I set the
> device-name property to be the wrong camera name the pipeline falls through
> without an exception being thrown. I've had a look at the other properties I
> could set on dshowvideosrc, but can't see anything that jumps out at me that
> I should configure.
> Is there anything else that you can think of that I could do?

You could tell us the output you get with the 2 following pipelines:

gst-launch-0.10 -v dshowvideosrc ! "video/x-dv, systemstream=0" ! fakesink


gst-launch-0.10 -v dshowvideosrc ! "video/x-dv, systemstream=1" ! fakesink

One should fail with a link error. The other one should lead to the crash
you got.

Then about the crash and the division by zero. I have some ideas but could
you tell us
if there is any framerate (fps) infos in the page properties of the filter
and the outpins using graphedit.
Finally right click on the output pin and then select render pin. Then play
the graph.
Does it play correctly?


> Phil
> 2009/6/25 Julien Isorce <julien.isorce at gmail.com>
>> 2009/6/25 Phil Rendell <philrendell at gmail.com>
>>> There is only one filter under the Video Capture Sources group: the
>>> Microsoft DV Camera and VCR. There are two output pins: DV A/V Out and DV
>>> Vid Out. All of the properties in DV A/V Out are disabled and are either
>>> empty or set to 'None', with the exception of the color space/compression
>>> (which is probably the one we're interested in) which is set to dvsd.
>>> The properties for DV Vid Out are the same as above, but without the
>>> color space/compression set.
>> Then I think gst-launch-0.10 dshowvideosrc ! fakesink can play (I should
>> ask you first) because dvsd is ok with the current implementation.
>> But in this case I can see from the implementation that dshowvideosrc
>> outputs
>> video/x-dv
>> You should see it using -v option.
>> Anyway, ffmpegcolorspace doest not handle video/x-dv, that's why you got
>> "WARNING: erroneous pipeline: could not link dshowvideosrc0 to
>> ffmpegcsp0"
>> Then you could try to insert a ffdec_dvvideo (if you have it) bettween
>> dshowvideosrc and ffmpegcolorspace.
>> (note that I do not know if gstreamer has a dv decoder that does not come
>> from gst-ffmpeg)
>> Sincerely
>> Julien
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