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Hi Clay,

there seems to be some uncertainty and misunderstanding, probably we are
using some common terms with a slightly different meaning. On the whole,
I get the impression we both want to express similar concepts. We are
both searching ways of keeping the handling of the Application clear
and understandable.


> On 17:22 Sun 20 Jul, Ichthyostega wrote:
>> Note further that I have assumed you can put clips on leaf tracks
>> only. If you group together some tracks, this creates a group head
>> track (parent track).
...

Clay Barnes schrieb:
> Perhaps I misunderstood your previous paragraph, but I think you're 
> proposing a 'parent track'/'grouping track' separate from the 
> multi-track container.  I am resistant to add the visual and 
> operational complexity distinguishing them in the interface would 
> entail.  I think that having only four components in the timeline 
> would still be fully expressive of any desired edits:
...

No, I don't think I am proposing a separate new grouping feature here.

Besides the track-tree, which I thought was something obvious.
Now, if I recall correct, we never actually discussed and considered
if we want a track-tree, because it seemed obvious. I vaguely recall
one of the first discussions with Cehteh somewhere in spring 2007.
Someone of us said something like "and btw., as we are partially
redoing things, of course we fix the tracks not being a tree"

The fact that tracks are /not/ a tree (but rather a flat list) in many
video editors, indeed today seems like a braindead design mistake.

Actually, if you consider history, it isn't so silly. Rather, I'd call
it "legacy". Remember, 20 years ago, many prominent people held up the
statement that you can't do "real film" editing with computers, just
"fastfood crap". You had to convince people to use computer based
editing, and of course everyone strived to make it feel as much as
possible like "real film". Thus we got "media bins", an "A roll" / "B
roll" video track with transitions in between,  and sound tracks are
nicely arranged separately like on good old multitrack magnetic tape
machines.

Meanwhile, maybe we still stick to it just out of habbit, but there
is not much technological reason for things being organized this way.

Today, none of the structures we see in the GUI of a video editor, is
actually involved in the technical process of rendering media data.

- - clips don't any longer "contain" the media, they only refer to it
- - tracks don't any longer "play back" the media, they are simply a
  place you can put things at.
- - the framerate is no longer built into the machine, rather it's just
  a property you choose for rendering.
and so on....

Thus, the following conclusions seem obvious to me:
- - Tracks can be nested like folders or other containers. They form a
  tree, can be collapsed and inherit relevant settings down to subtracks
  (lockining, enabled, output port, fader setting etc.)
- - a clip has start, length and source position and refers to some
  source media
- - media always inherently contains multiple channels, which are tied
  together and used in sync.
- - most of the "wiring" can be done automatically, simply by considering
  the stream type and mixing it into the appropriate output port. Only
  in special and rather rare cases the user needs to define the
  output/wiring explicitly.
- - there is no difference between a "normal" clip and a "meta clip". They
  just refer to a different kind of media (an external media file versus
  the output port of another timeline)
- - there is no technical reason why the program should inhibit the user
  in mixing clips with various different media types, frame rates,
  channel counts etc. on the same track, because the track doesn't
  "playback" the media.
- - there is no reason why you should be restricted to "apply" an effect
  only to an complete clip. Effects can span multiple clips and even be
  faded and crossfaded separately from the media.

Many of today's existing video editing applications get some or all of
those points wrong, probably because of sticking to some legacy state
of affairs. Indeed, any of those points enlisted above, if overlooked,
can cause a lot of unneeded code complexity and force quite some amount
of unnecessary and stupid work on user.

In our case, having to edit a movie imposes quite a bit of essential
complexity. You have to care for lots of details and consider some
subtle points, otherwise the work isn't professional.


Clay Barnes schrieb:
> The limitation of inputs for the (compound)filters to entire media 
> containers and media files on the same level provides a substantial 
> reduction in visual/code complexity, resolves some nasty potential 
> graph cycle bugs, and heads off some hard questions about edits that 
> involve the contents of both unlocked and locked media containers.  I
>  think the very small reduction in flexibility is a blessing---the 
> whole point of the media container concept is to 'encapsulate' their 
> contents, so interaction with them that deals with the sub-objects or
>  crosses their boundaries is actually confusing/counterintuitive to 
> users.
I fully agree with the latter statement: a meta-clip should be opaque.
I the user wants to edit its internals, (s)he should "open" the
meta-clip which would just switch to another timeline window tab.

I don't understand your argument at the beginning of the paragraph.
Letting aside that it's never a good idea to design the UI such as to
avoid implementation bugs, we simply aren't in the situation to decide
on "limitations" here. What is needed is dictated by actual necessities.
Regarding Effects:
- - you have effects in a global bus insert (e.g. global deinterlacer)
- - you have effects on some timespan, irrespective of the content. This
  kind of effects are very frequently combined with automation.
- - you have effects applied to a whole clip
- - you have effects which need to be applied to a specific source media
- - you have effects applied just to a part of a clip, typically with
  automation
- - you have the situation where an effect spans a transition.

All of these cases are everyday situations. You do no one a favour if
you try to inhibit some of those cases, you just force people to use
workarounds, often with serious consequences on the whole project.


> Sudden idea:  As a parallel to the idea of cuts in source media, the 
> corresponding effect (crop off the ends) should be easily performed
> on the media containers, too.

You are asking the wrong question. Not "how can containers be made to
behave somewhat similar to normal clips"?  This way you are creating
"accidental complexity".

The right question is: "is there any difference between the handling
of real clips and meta-clips? What has to behave different?"
And the answer is: there is none.
They are just using a different kind of source media, that's all.
(you can "edit" this source media of the meta-clip in another timeline,
while you can't "edit" the source media from a media file or life
input). You can trim, splice, rearrange, and combine them like normal
clips and all of this doesn't cost a single line of additional code.


> Note that two media containers cannot share the same track (unlike 
> dropping one video after another on the same video track)---trying to
> do so ends up with a mess whenever there are different numbers of
> content tracks for each container.

First of all, we should be careful with our terminology.
A media doesn't contain "tracks", it contains N separate *streams*.
Each stream has a stream-type.

A track, on the contrary doesn't contain media data, it doesn't
"playback" or "mix" media (the latter is the job of the render- or
processing engine). Consequently, it doesn't, on itself, have a
stream-type. A track is just a place to arrange clips and effects,
nothing more. There is no reason why you should artificially limit
the kind of clips which can be put next to one another.

There is a GUI design problem though: how to draw the visualisation
or preview of the clips? Do we really need to see the various possible
streams within a single clip displayed "inline", in the timeline view??
While, for example, displaying a mono waveform is certainly helpful,
showing 9 tiny, almost identical waveforms of an 2nd order Ambisoncs
track is quite silly. For the purpose of editing, it would be fully
sufficient to show the waveform of the W channel (sound pressure sum).
Similar argument for a clip containing three video channels from
a multi-camera setup.

...
> before the beginning crop and after the end crop, all of the content
> of the media container can still be seen and edited, but it is faded
> to indicate the 'invisibility' of that content.

This sounds like a nice idea to me. Of course there is no reason why
such a feature shouldn't be available for real clips too.

In a similar vein, do you know the "region transparency" in Ardour?
In Ardour you can stack regions on top of each other as you like,
but the topmost region always covers what's "below". But if you
switch the region to "transparent", you can hear a mix of both
and you can see the waveform of the region "below" shine through
the transparent waveform of the "upper" region.
(In Ardour, "region" denotes what we call a "clip")

>> Lets assume you lock a track containing an media object "A". Lets
>> further assume there is another object "B" placed on another track
>> 
>> Case 1:....

> I am either misreading your text or I think you might have made some 
> small media reference errors, below is my interpretation of your 
> intended meaning:

Well, I can't see any difference between both descriptions (besides
the small implementation detail when to re-adjust the offset). So
I take it that we both judge the situation similarly.

> 
> I agree that this is a good handling of relative placement 
> interactions with locked tracks.  The visual cue for Case 1 should be
> the same one used by Case 2 (and the default relative motion case).
> I am imagining something like a red line with text indicating the
> time of the relative offset bracketed by the related track's defining
> edges.  An image of an anchor (the nautical tool) on the end of the 
> track that defines the relative placement would clearly show 
> directionality of the relationship.

Yeah, sounds like a good way of visualizing this relationship.
(ok, I am aware that implementing such behaviour may have some rough
edges, but from a usage point of view its easy to grasp)

Cheers,
Hermann V.

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