Basics of gstreamer pipeline

[praveen]

I have just started understanding the gstreamer basics and while going
through some examples, I had few questions.

Can some please explain me the following:

In the pipeline,

gst-launch videotestsrc ! ffmpegcolorspace ! ximagesink

What cololorspace does videotestsrc  produce here?
What colorspace conversion is ffmpegcolorspace doing?
What colorspace is ximagesink accepting and where is it presenting,
Framebuffer??

Here we dont mention any properties for the plugin, but still how do they
co-work?

I am confused in understanding
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[Tim-Philipp Müller-2]

On Wed, 2012-10-31 at 18:17 +0900, Praveen Adi wrote:

Hi,

> Can some please explain me the following:
>
> In the pipeline,
>
> gst-launch videotestsrc ! ffmpegcolorspace ! ximagesink
>
> What cololorspace does videotestsrc  produce here?

It will query ffmpegcolorspace for what it supports, which in turn will
query ximagesink for what it supports (so that what ximagesink supports
can be prefered).

It will likely produce whatever colorspace/pixel layout ximagesink
returns first in the caps it returns from its get_caps() function.

> What colorspace conversion is ffmpegcolorspace doing?

If videotestsrc can produce every format ximagesink could possibly
support, then no conversion will be done. ffmpegcolorspace will operate
in passthrough mode.

> What colorspace is ximagesink accepting and where is it presenting,
> Framebuffer??

It depends on the driver/card. It will be determined at runtime what
formats are supported. It's likely going to be some RGB format.

You can see the caps negotiated if you pass -v to gst-launch.

> Here we don't mention any properties for the plugin, but still how do
> they co-work?

Not sure I understand the question, could you rephrase it?

Cheers
 -Tim

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[praveen]

Hi Tim,

Thanks for the detailed answer.

It really helped me in getting a better picture.

Regards,

Praveen

On Wed, Oct 31, 2012 at 7:27 PM, Tim-Philipp Müller <[hidden email]> wrote:

On Wed, 2012-10-31 at 18:17 +0900, Praveen Adi wrote:

Hi,

> Can some please explain me the following:
>
> In the pipeline,
>
> gst-launch videotestsrc ! ffmpegcolorspace ! ximagesink
>
> What cololorspace does videotestsrc  produce here?

It will query ffmpegcolorspace for what it supports, which in turn will
query ximagesink for what it supports (so that what ximagesink supports
can be prefered).

It will likely produce whatever colorspace/pixel layout ximagesink
returns first in the caps it returns from its get_caps() function.

> What colorspace conversion is ffmpegcolorspace doing?

If videotestsrc can produce every format ximagesink could possibly
support, then no conversion will be done. ffmpegcolorspace will operate
in passthrough mode.

> What colorspace is ximagesink accepting and where is it presenting,
> Framebuffer??

It depends on the driver/card. It will be determined at runtime what
formats are supported. It's likely going to be some RGB format.

You can see the caps negotiated if you pass -v to gst-launch.

> Here we don't mention any properties for the plugin, but still how do
> they co-work?

Not sure I understand the question, could you rephrase it?

Cheers
 -Tim

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[Krzysztof Konopko]

Please note though that "ffmpegcolorspace was removed and replaced with
videoconvert." in GStreamer-1.0.

See
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-porting-1.0.html
for more details if you intend to use 1.0.

Kris

On 31/10/12 20:14, Praveen Adi wrote:

> Hi Tim,
>
> Thanks for the detailed answer.
> It really helped me in getting a better picture.
>
> Regards,
> Praveen
>
> On Wed, Oct 31, 2012 at 7:27 PM, Tim-Philipp Müller <[hidden email]
> <mailto:[hidden email]>> wrote:
>
>     On Wed, 2012-10-31 at 18:17 +0900, Praveen Adi wrote:
>
>     Hi,
>
>     > Can some please explain me the following:
>     >
>     > In the pipeline,
>     >
>     > gst-launch videotestsrc ! ffmpegcolorspace ! ximagesink
>     >
>     > What cololorspace does videotestsrc  produce here?
>
>     It will query ffmpegcolorspace for what it supports, which in turn will
>     query ximagesink for what it supports (so that what ximagesink supports
>     can be prefered).
>
>     It will likely produce whatever colorspace/pixel layout ximagesink
>     returns first in the caps it returns from its get_caps() function.
>
>     > What colorspace conversion is ffmpegcolorspace doing?
>
>     If videotestsrc can produce every format ximagesink could possibly
>     support, then no conversion will be done. ffmpegcolorspace will operate
>     in passthrough mode.
>
>     > What colorspace is ximagesink accepting and where is it presenting,
>     > Framebuffer??
>
>     It depends on the driver/card. It will be determined at runtime what
>     formats are supported. It's likely going to be some RGB format.
>
>     You can see the caps negotiated if you pass -v to gst-launch.
>
>     > Here we don't mention any properties for the plugin, but still how do
>     > they co-work?
>
>     Not sure I understand the question, could you rephrase it?
>
>     Cheers
>      -Tim
>
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>     <mailto:[hidden email]>
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>
>
>
>
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[praveen]

Thanks Kris for the information.

On Thu, Nov 1, 2012 at 7:29 AM, Krzysztof Konopko <[hidden email]> wrote:

Please note though that "ffmpegcolorspace was removed and replaced with
videoconvert." in GStreamer-1.0.

See
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-porting-1.0.html
for more details if you intend to use 1.0.

Kris

On 31/10/12 20:14, Praveen Adi wrote:
> Hi Tim,
>
> Thanks for the detailed answer.
> It really helped me in getting a better picture.
>
> Regards,
> Praveen
>
> On Wed, Oct 31, 2012 at 7:27 PM, Tim-Philipp Müller <[hidden email]

> <mailto:[hidden email]>> wrote:
>
>     On Wed, 2012-10-31 at 18:17 +0900, Praveen Adi wrote:
>
>     Hi,
>
>     > Can some please explain me the following:
>     >
>     > In the pipeline,
>     >
>     > gst-launch videotestsrc ! ffmpegcolorspace ! ximagesink
>     >
>     > What cololorspace does videotestsrc  produce here?
>
>     It will query ffmpegcolorspace for what it supports, which in turn will
>     query ximagesink for what it supports (so that what ximagesink supports
>     can be prefered).
>
>     It will likely produce whatever colorspace/pixel layout ximagesink
>     returns first in the caps it returns from its get_caps() function.
>
>     > What colorspace conversion is ffmpegcolorspace doing?
>
>     If videotestsrc can produce every format ximagesink could possibly
>     support, then no conversion will be done. ffmpegcolorspace will operate
>     in passthrough mode.
>
>     > What colorspace is ximagesink accepting and where is it presenting,
>     > Framebuffer??
>
>     It depends on the driver/card. It will be determined at runtime what
>     formats are supported. It's likely going to be some RGB format.
>
>     You can see the caps negotiated if you pass -v to gst-launch.
>
>     > Here we don't mention any properties for the plugin, but still how do
>     > they co-work?
>
>     Not sure I understand the question, could you rephrase it?
>
>     Cheers
>      -Tim
>
>     _______________________________________________
>     gstreamer-devel mailing list
>     [hidden email]

>     <mailto:[hidden email]>
>     http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

>
>
>
>
> _______________________________________________
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>

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