duration and media-duration in GnlObject

[vineeth]

Hi,

  Thanks for the clarifications.


On Sat, Aug 6, 2011 at 1:48 PM, Edward Hervey <bilboed at gmail.com> wrote:

> Hi,
>
> On Fri, 2011-08-05 at 17:11 +0530, vineeth wrote:
> > Hi,
> >   I wanted to know the difference between "duration" and
> > "media-duration"  in GnlObject and I couldn't comprehend this clearly
> > from the documentation.
>
>   Duration is for how long something will be played from the outside.
>  Media-duration is how long you're taking from the contained media.
>
>  99.99% of the time you want media_duration == duration.
>
>  If you want a source to play faster/slower (without any extra cost),
> you can modify those values accordingly.
>  Ex : I want to playback an intro video two times slower. That video is
> originally 3s:
>   media_duration = 3s
>   duration = 6s
>
>  The rate is computed from the duration/media_duration values
> automatically, it's just provided as a convenience.
>
> >   If I want the Gnl pipeline to render at a faster rate, (but without
> > changing the timestamp of sources) which property should I change? I
> > read that rate is a read-only property.
>
>   You can either:
>  * Seek with a rate of 0.5 if you just want to play it back slower
>  * OR you'll have to modify all the source duration/media_duration
> values accordingly.
>

I was trying a mp4 (with h264) trim on 0.10.32

When the duration was made half of media-duration, I was expecting the
pipeline to run faster, however, I didn't see any significant change in save
time (compared to case where duration and media-duration are same).

for ex:

gst-launch gnlcomposition { gnlfilesource name="s1"
location="/mnt/hgfs/ubuntu_shared/h264/4.mp4"  start=0 duration=10000000000
media-start=0 media-duration=10000000000 } ! ffmpegcolorspace ! x264enc !
mp4mux ! filesink location="/mnt/hgfs/ubuntu_shared/output-d-10-md-10.mp4"

Time take : ~41 seconds


gst-launch gnlcomposition { gnlfilesource name="s1"
location=/mnt/hgfs/ubuntu_shared/h264/4.mp4  start=0 duration=5000000000
media-start=0 media-duration=10000000000 } ! ffmpegcolorspace ! x264enc !
mp4mux ! filesink location=/mnt/hgfs/ubuntu_shared/output-d-5-md-10.mp4
 Time take : ~41 seconds

Our intention is to speed up the gnl pipeline so that the media content is
saved faster. Is there anything missing / incorrect in the above pipeline?



>
>    Edward
>
> >   Thanks.
> > --vineeth
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> > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
>
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