[Kdenlive-devel] Usability test (by me!)

[Rolf Dubitzky]

On Wednesday 20 August 2003 11:50 pm, Jason Wood wrote:
> 1. The first step I had was therefore converting them to rawdv - not too
> hard but not done via Kdenlive, I used Kino to do this. I missed the fact
> that there appears to be no way to batch-convert files to a new format, but
> then, that's not really what kino is there for.

;-) but that what piave is there for. You could probably do this at the 
command line with piave_CVS-00-03-devel. Even better, you could just use the 
.avi files ;-)

> - The first thing was sound sync with the video. Rolf has already mentioned
> this is improved in the 0.3.0 branch of piave by using arts directly, but
> it is very annoying trying to watch back your movie and "mentally shift"
> the sound back to where it's supposed to be.

Yes, this is a problem. mplayer and xine both assume some audio latency based 
on experience and allow to in/decrease AV-delay while watching. I will 
probably have to do something similar. Maybe we can privide a small clip with 
a flap, so you adjust some kind of latency parameter for you system.
Not using artdsp, however, does already help a lot. 

> - I had the same shot filmed at two different camera angles. Syncing up the
> video/sound was relatively straight forward. But damn, the sound quality
> between the cameras was so different it was way too noticable! The real
> solution to this is to have video seperate to sound, so that one camera's
> sound (or an mp3/off/wav file) can be used throughout and the other
> video(s) simply displayed over the top.

;-) almost done ;-)   the piave version on my laptop can read wav/ogg/mp3 and
... well, and nothing more, not play anything or re-encode, but I am currently 
working on it. I think blending audiotracks together is not too far away, 
too.


> - Because the cameras both had mono sound, the dv files were the same -
> functionality to take sound from either the left or right channel and use
> it for both channels is a must.

ok. trivial, that can be done. the main problem is probably to invent VEML to 
do it.

> - On the back of this, I missed not being able to fade sound in/out :-)

well, up to now, there is not a single audio-effect, only some video effects 
in various states of bitrot. But since I finished my thesis a few days ago, 
and started working on exactly this, I think you can have a 
audio-volume-filter pretty soon. BTW, taking audio from one DV file and put 
it into the other does workalready, there is just no VEML for it.

> - video crossfade - for the clips I was editing together, a simple
> crossfade effect would have been quite adequate to make the end result much
> better.

piave can do this. the effect suffers some minor bitrot. and, more important, 
we have no really working VEML definition for effects (and no GUI ;-)


> Things that would have been nice :
>
> - Having sound images in Kdenlive so that you can visually see the 'beats'
> in music, or when somebody starts speaking.
>
> - If piave crashes, it does take a minute or so before a connecion can be
> re-established. Some sort of rotation of port numbers so that a new port is
> tried each time should help remove this problem completely. This does not
> mean that we should stop bug-fixing though!!! :-)

this just treats the symptom. I just have to look into a network programming 
howto. There are two things to it:
1)  Fix the tcp/ip communication and make the socket be freed in case of a
    crash
2)  detect when piave and kdenlive are running on the same host and replace 
    the tcp socket by a unix domain socket. This will improve speed and 
    especielly reduce latency a lot. This is what XWindows does and can be 
    done by changing a hand full of source code lines.



> - Being able to select in/outpoints works like a dream!
> - The piave in the workspace monitor crashed once or twice , I did not lose
> my project! (There seems to be an issue with long timelines, piave inserts
> <message></message> tags which do not always make the end scenelist valid
> XML. I hope to look into this, since I want to rationalize the XML code in
> Kdenlive at least anyway.)
> - The rendering was nice and fast, and came out exactly as it played during
> the edit.

That makes me happy ;-) However, it is not too surpizing that it was fast, 
since you probably didn't do any real rendering at all. And since piave is 
designed by the principle of delayed action, which means that a video or 
audio frame in the render tree is only decoded as soon as it is _really_ 
necessary to alter the video/audio information. If you don't do anything, 
just cut/rearange, the video/audio is not decoded at all. That also means, 
that you don't have _any_ kind of quality loss. you can rearange your clips 
as often as you like. (at least in DV format)

> Right, I'll switch back to the developers hat. Please feel free to comment!

I think I will merge the avi and sound stuff from the devel branch to the main 
branch as soon as seperate audio tracks are working. We should try and get 
another synchronized kdenlive/piave release, 0.2.4/5 or something.
mpeg support is not something that will work in the next weeks. This will 
probably help people testing the stuff. I would also like to supply some 
packages. I guess we probably have enough people here to  make Mandrake, 
RedHat, and debian packages. Since I will be moving to another town to start 
a new job at Sep. 1st, I guess maybe we can aim at the first or second week 
of Sept. for this, what do you think?

-- 
Cheers,
Rolf

***************************************************************
 Rolf Dubitzky  
 e-mail: Rolf.Dubitzky at Physik.TU-Dresden.de
 s-mail see http://hep.phy.tu-dresden.de/~dubitzky/
***************************************************************