[vlmc-devel] [GSoC] Audio/Video sync discussion

[Hugo Beauzée-Luyssen]

Hi,

Sorry I'm late to reply.
Answers are inline:

On 03/19/2016 04:49 PM, Paweł Goliński wrote:
> Some more questions:
>
> 4. Is fixing whole editing workflow a part of this project? As it stands
> now, I can’t save/export/preview any project on my computer (and AFAIK
> its the way VLMC behaves everywhere), and I see the implementation of
> audio/video sync as encapsulated clock mechanism, that would eventually
> connect somewhere (renderer? workflow?). The problem is, if by the end
> of clock implementation, all underlying mechanisms doesn’t work
> properly-ish it would be hard to connect it anywhere. And
> repairing/refactoring everything sounds like a different project…

I'm trying my best to fix it. I think it would be worth tackling the 
issue hand in hand with the unit test project (which might depend on the 
number of slots we have) so that the clock is unit tested.
This should give us enough time to clean/fix things.

>
> 5. If it’s [question 4] a part of the project, would it be ok if the
> audio/video sync mechanism is not fully implemented by the end of GSoC?
> I assume that it would take A LOT of time to make VLMC usable, and the
> audio/sync between multiple video sources is another non-trivial
> problem. If it’s not a part of the project, will it be implemented
> before, let’s say, half of the GSoC work period? If not, what is the
> expected result of the GSoC project? (Again, to connect a clock to some
> mechanism, this mechanism should already work…)
>

My personal opinion is that a student shouldn't be affected in his 
evaluation if the problem was there to begin with, but it shouldn't also 
be used as an excuse to not work on what's doable.
To put it another way, if the rendering doesn't work, I can't except the 
"clock" project to work with a real video. However, if the student 
addressing this task just sit and waits until the rendering is fixed, 
this is not ok, since there are ways to move forward.

>
>> Wiadomość napisana przez Paweł Goliński <golpaw1 at gmail.com
>> <mailto:golpaw1 at gmail.com>> w dniu 19.03.2016, o godz. 16:37:
>>
>> OK, I’ll try.
>>
>> 1. What exactly is the problem with audio/video sync? I mean, where
>> does it emerge? Is it a problem with the timeline, that all streams
>> injected into timeline are out of sync between each other, or what?
>> (VLMC is pretty much non-functional on my computer when it comes to
>> using any feature connected to video editing, so I can’t check this
>> myself).
>>

It's hard to demonstrate without a functional rendering, but basically, 
if you import a video, and simply render it to a file, you have a good 
chance of seing the audio and the video lose sync, as time passes.

>> 2. Does clip preview work? AFAIK, it uses different rendering
>> mechanism than project preview, so it should be OK, right?
>>

Clip preview should be 100% functional.

>> 3. What is the expected result from video/audio sync project? I mean,
>> is there a sample use case scenario, on which it can be demonstrated?
>> (What’s the use case? How it’s broken now? How should it behave after
>> audio/video sync is implemented?)
>>

That seems similar to your question 1, but the quick answer is, if I 
import a video, and render it without any editing, it should look & 
sound exactly the same as the input material.

>>> Wiadomość napisana przez yikei lu <luyikei.qmltu at gmail.com
>>> <mailto:luyikei.qmltu at gmail.com>> w dniu 19.03.2016, o godz. 16:04:
>>>
>>> hi,
>>
>
>
>
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Regards,