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Changing play rate in a GnlFileSource element

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Andoni Morales

Changing play rate in a GnlFileSource element

I want to extract a video segment of a stream and encode it into a new
file at a different play rate.

I am wondering if it's possible to change the play rate of the stream
obtained from the GnlComposition element by setting the "duration"
property of the GnlFileSource element X time longer than the
"media-duration" property, for example:

start=0;
duration=10,
media-start=10;
media-duration=15;

Does this paramaters sets the "rate" property of the GnlFileSource to
1/2 or do I rather have to use a GnlOperation element with the
videorate element?

Andoni

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Edward Hervey

Re: Changing play rate in a GnlFileSource element

Administrator

On Tue, 2009-05-26 at 19:18 +0200, Andoni Morales wrote:

> I want to extract a video segment of a stream and encode it into a new
> file at a different play rate.
>
> I am wondering if it's possible to change the play rate of the stream
> obtained from the GnlComposition element by setting the "duration"
> property of the GnlFileSource element X time longer than the
> "media-duration" property, for example:
>
> start=0;
> duration=10,
> media-start=10;
> media-duration=15;

That will make the output playback at (15/10=) 1.5 times the normal
playback speed.

The 'media_duration' is how much will be taken from the contained
stream,
The 'duration' is for how long it will be played back.

If you want the file to playback at half speed, you'll need to make
the duration twice as long as the media-duration (thereby playing back X
seconds in 2*X seconds).

>
> Does this paramaters sets the "rate" property of the GnlFileSource to
> 1/2 or do I rather have to use a GnlOperation element with the
> videorate element?

It will set the rate of the outgoing segment but will not modify the
timestamps/frequency of the buffers.
You will need to add the following on the output of your gnlfilesource
in order for the timestamps/newsegment to be transformed accordingly:

gnlfilesource ! identity single-segment=True ! videorate !
yourencoder ...

Edward

>
> Andoni
>
> ------------------------------------------------------------------------------
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> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
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> _______________________________________________
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Andoni Morales

Re: Changing play rate in a GnlFileSource element

2009/5/26 Edward Hervey <[hidden email]>:

> On Tue, 2009-05-26 at 19:18 +0200, Andoni Morales wrote:
>> I want to extract a video segment of a stream and encode it into a new
>> file at a different play rate.
>>
>> I am wondering if it's possible to change the play rate of the stream
>> obtained from the GnlComposition element by setting the "duration"
>> property of the GnlFileSource element X time longer than the
>> "media-duration" property, for example:
>>
>> start=0;
>> duration=10,
>> media-start=10;
>> media-duration=15;
>
> That will make the output playback at (15/10=) 1.5 times the normal
> playback speed.
>
> The 'media_duration' is how much will be taken from the contained
> stream,
> The 'duration' is for how long it will be played back.
>
> If you want the file to playback at half speed, you'll need to make
> the duration twice as long as the media-duration (thereby playing back X
> seconds in 2*X seconds).

You are right, I made a mistake calculating the output rate... ;)

>
>>
>> Does this paramaters sets the "rate" property of the GnlFileSource to
>> 1/2 or do I rather have to use a GnlOperation element with the
>> videorate element?
>
> It will set the rate of the outgoing segment but will not modify the
> timestamps/frequency of the buffers.
> You will need to add the following on the output of your gnlfilesource
> in order for the timestamps/newsegment to be transformed accordingly:
>
> gnlfilesource ! identity single-segment=True ! videorate !
> yourencoder ...

If for example, I need to use a GnlComposition to extract several
segments of the same file, but with different play rates (for example
to get in the output file the same segment 3 times, but at 1x, 1/2x
and 1/4x), can I use the previous pipeline but replacing
'gnlfilesource' with 'gnlcomposition'?

Thanks,
Andoni

>
>
> Edward
>
>>
>> Andoni
>>
>> ------------------------------------------------------------------------------
>> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>> is a gathering of tech-side developers & brand creativity professionals. Meet
>> the minds behind Google Creative Lab, Visual Complexity, Processing, &
>> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>> _______________________________________________
>> gstreamer-devel mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>
>
> ------------------------------------------------------------------------------
> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> is a gathering of tech-side developers & brand creativity professionals. Meet
> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>

Edward Hervey

Re: Changing play rate in a GnlFileSource element

Administrator

> If for example, I need to use a GnlComposition to extract several
> segments of the same file, but with different play rates (for example
> to get in the output file the same segment 3 times, but at 1x, 1/2x
> and 1/4x), can I use the previous pipeline but replacing
> 'gnlfilesource' with 'gnlcomposition'?

Yes of course :) That's what we do in pitivi for example.

Edward

>
> Thanks,
> Andoni
>
> >
> >
> > Edward
> >
> >>
> >> Andoni
> >>
> >> ------------------------------------------------------------------------------
> >> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> >> is a gathering of tech-side developers & brand creativity professionals. Meet
> >> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> >> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> >> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
> >> _______________________________________________
> >> gstreamer-devel mailing list
> >> [hidden email]
> >> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
> >
> > ------------------------------------------------------------------------------
> > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> > is a gathering of tech-side developers & brand creativity professionals. Meet
> > the minds behind Google Creative Lab, Visual Complexity, Processing, &
> > iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> > Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
> > _______________________________________________
> > gstreamer-devel mailing list
> > [hidden email]
> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
>
> ------------------------------------------------------------------------------
> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> is a gathering of tech-side developers & brand creativity professionals. Meet
> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
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Andoni Morales

Re: Changing play rate in a GnlFileSource element

2009/5/26 Edward Hervey <[hidden email]>:
>
>> If for example, I need to use a GnlComposition to extract several
>> segments of the same file, but with different play rates (for example
>> to get in the output file the same segment 3 times, but at 1x, 1/2x
>> and 1/4x), can I use the previous pipeline but replacing
>> 'gnlfilesource' with 'gnlcomposition'?
>
> Yes of course :) That's what we do in pitivi for example.

Great! Thank you again!

Andoni

>
> Edward
>
>>
>> Thanks,
>> Andoni
>>
>> >
>> >
>> > Edward
>> >
>> >>
>> >> Andoni
>> >>
>> >> ------------------------------------------------------------------------------
>> >> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>> >> is a gathering of tech-side developers & brand creativity professionals. Meet
>> >> the minds behind Google Creative Lab, Visual Complexity, Processing, &
>> >> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>> >> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>> >> _______________________________________________
>> >> gstreamer-devel mailing list
>> >> [hidden email]
>> >> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>> >
>> >
>> > ------------------------------------------------------------------------------
>> > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>> > is a gathering of tech-side developers & brand creativity professionals. Meet
>> > the minds behind Google Creative Lab, Visual Complexity, Processing, &
>> > iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>> > Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>> > _______________________________________________
>> > gstreamer-devel mailing list
>> > [hidden email]
>> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>> >
>>
>> ------------------------------------------------------------------------------
>> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>> is a gathering of tech-side developers & brand creativity professionals. Meet
>> the minds behind Google Creative Lab, Visual Complexity, Processing, &
>> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>> _______________________________________________
>> gstreamer-devel mailing list
>> [hidden email]
>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>
>
> ------------------------------------------------------------------------------
> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> is a gathering of tech-side developers & brand creativity professionals. Meet
> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>