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Set Video caps after playing

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Alexandre Rosenfeld

Set Video caps after playing

Hi,

I'm doing video conversion using GStreamer, and one of things I need is to scale down a video, if it is bigger then allowed.
I've setup a pipeline using decodebin, and I was able to use the videoscale plugin by setting some fixed caps, but I want to set these caps only when the video dimensions are bigger then allowed. As I far as I understand it, I need to have the caps negociated to get the video dimensions, but then I can't set the caps I want. Is this right? How can I do what I want?

Thanks in advance

--
Alexandre Rosenfeld

EngComp 06 - USP São Carlos

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Thiago Sousa Santos-2

Re: Set Video caps after playing

On Tue, Jul 15, 2008 at 4:42 AM, Alexandre <[hidden email]> wrote:

Hi,

I'm doing video conversion using GStreamer, and one of things I need is to scale down a video, if it is bigger then allowed.
I've setup a pipeline using decodebin, and I was able to use the videoscale plugin by setting some fixed caps, but I want to set these caps only when the video dimensions are bigger then allowed. As I far as I understand it, I need to have the caps negociated to get the video dimensions, but then I can't set the caps I want. Is this right? How can I do what I want?

You can get the caps when decodebin adds a new pad, and at this time you analyze its caps to decide if you need videoscale or not.

Thanks in advance

--
Alexandre Rosenfeld

EngComp 06 - USP São Carlos

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-thiago

Alexandre Rosenfeld

Re: Set Video caps after playing

On Wed, Jul 16, 2008 at 5:47 PM, thiagoss <[hidden email]> wrote:

You can get the caps when decodebin adds a new pad, and at this time you analyze its caps to decide if you need videoscale or not.

-thiago

But as far as I know, those caps describe what could be negociated (from pad templates), not the actual data.
For the video streams I'm trying, all it reports is 'video/x-raw-rgb; video/x-raw-yuv'.
I need to change the caps after they have been negociated.
I think I might have to write an element for this, and implement caps negociation as shown in http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/section-nego-downstream.html
But it will be complicated. Is there a better option?

Thanks,
Alexandre

--
Alexandre Rosenfeld

EngComp 06 - USP São Carlos