Re: [Mlt-devel] More robust producer lengths?

[Dan D. <da...@de...>]

On Sat, Apr 30, 2011 at 5:39 AM, anders musikka
<and...@gm...> wrote:
> Hello!
>
> Thank you very much for the patch.
>
> Sorry for not responding early, have had a few boring things that
> needed doing ... :-)
>
> I've done some experiments, and this is what I have found:
>
> 1: The code added by the patch does not execute, when I use openshot to render
> my minimal test case.
>
> Also, there are neither any white frames inserted, nor is the last
> frame repeated.
>
> I added some printouts to producer_get_image, and I can see that it seems to
> be called once for every frame that is actually present in the source
> clip. After
> playback reaches the end of the source clip, produce_get_image is not
> called at all.
>
> 2: If I use melt, as you suggested, giving an out parameter after the
> end of the file,
> the output is what would be expected - the last frame IS duplicated.
>
> I'm not sure what to make of this.
>
> I've attached an .mlt file generated by Openshot, which demonstrates
> the problem.
> It is a rather minimal example. It doesn't seem to make much difference what the
> actual clips are, so I'm not including any clips. Just take some
> random clip, and
> change its name to "four_and_a_half_second_clip.MOV", and then render the
> .mlt-file using melt, and I hope the problem can be reproduced. It is important
> that the clip is ~4.5 seconds long, if the clip is longer, everything seems
> to work.

I did that.

> The expected behaviour is that the clip plays for slightly more than 3 seconds,
> then there is some "blank", and then at exactly 4 seconds (frame number 100),
> the clip comes back in.

Your XML says <producer in="81.0" novdpau="1" out="162.0">
But 162 @ 25 fps is 6.48s. How can you expect it to to "play" longer
than the end of the file? Why did OpenShot let you use a portion
beyond the end of the file?

> However, that is not what I get. Instead, the first clip only plays
> until it runs out of
> frames, then the 18-frame blank appears prematurely, which means that the second
> showing of the clip is way early. (Which of course would make any
> transitions/effects
> be badly timed).

If one wants to exceed the length of a clip it must do so explicitly
by adding the "length" attribute to that producer element:
length="163". Then it exhibits this behavior you expect. I do not feel
the need to make any further changes.

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