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Patrick Shirkey wrote:
Hi,
I have just spent the past few days working on a project to sync a badly
recorded a/v track.
In the process I have had to do a crash course in Linux Multimedia apps.
It's like going back 5 years compared to Linux Audio. I haven't had to
do this kind of compiling for quite some time with Linux Audio apps due
to the Fedora yum repository being upto date and the stability issues
for basic operations have been sorted. Most of the audio apps I use just
work on 64 bit for basic editing tasks.
I have used several programs in my quest for a/v sync.
Avidemux
openmovieeditor
kdenlive
LiVES
cinelerra-cv (community version)
kino
I have also used
ffmpeg
mencoder
mplayer
gmerlin
I also would have liked to try out jahshaka /cinefx and cinelerra-4 but
I couldn't get either installed. I ended up using avidemux and
openmovieeditor.
I had to install several apps from source due to various bugs that
happen on my dual core amd , fedora 10 x64 packaged versions. Many of
the apps have got Fedora 10 rpm builds but it took several hours of
searching google to find the links and details for installing them. Then
I had the headache of figuring out why libs that were compiling and
installing were not being found as deps. Why does Fedora not setup the
qt4 and pkgconfig paths by default? Has that been fixed in Fedora 11?
For a development install this seems like a prerequisite.
In the end after 30 hours of trying to use the various apps above to
realign a single audio track the best I could do was to extract the
audio track from the original with mplayer -dumpaudio, cut the original
mpg with avidemux, render (export) the new track to disk, split off the
audio track with mplayer, import the original audio track to audacity,
cut it to the right start points, export it to wav, import the new
tracks to openmovieeditor, align them, export them to .mov.
yay: Unix spirit: one tool per task ;)
I'm surprised that openmovieeditor failed. It works pretty stable here
for doing simple editing. kino even more so.
As for aligning and editing audio; I'd recommend ardour over audacity.
You can see the video in sync with xjadeo. Ardour can read timecode from
the broadcast-info in the audio-file's header and automatically align
chunks/regions in a session.
Your final step of multiplexing and transcoding can be done on the
commandline. eg. for a PAL-DVD with two audio-tracks:
ffmpeg -target pal-dvd -b 9000k -bt 1000k -i film.avi -acodec mp2 -ab
192k -alang en -i bounce_stereo.wav -acodec ac3 -ab 384k -ac 6 -alang en
- -newaudio -i bounce_cinema.ac3 -map 0:0 -map 1:0 -map 2:0
/tmp/master.mpg -author xxx -title "Title" -year 2009
The devede(1) GUI can build this command for you.
I would have preferred to use one app but none of them
could do all of
the above or if they could they were buggy and kept crashing or couldn't
read the mp3 or couldn't export the file in a readable format, etc....
Kdenlive looked like it would be almost perfect but it kept crashing,
openmovieeditor is also good but editing is limited and buggy, of them
all avidemux was definitely the most rock solid performer and the
interface was a pleasure to work with. LiVES has a nice clean interface
too but is not really an editor. The other apps left a lot to be desired
in the visual appeals dept. Why do multimedia devs insist on using the
gui libraries like sdl and tkinter?
BTW, why the different jargon for audio (export) and video (render)
processing?
I guess that's because historically they were coined and used by
different departments. BTW. Audio-export is still often called "bounce"
(analog tape-tracks).
Rendered or bounced tracks are always processed-data. However an
"Export" can also just be raw-data & edit-info. Modern Workflow has
somewhat blurred the lines here.
What I am sorely missing is a video time stretch
function as the final
edit is still badly out of sync.
While some software-players support it, many video playback devices are
limited to 24, 25, 29.97 or 30 fps. - Time-stetching film by non-integer
multipliers is tricky. google for eg. telecine, pulldown.
Usually you're better of editing, re-sampling or time-streching the
audio. *hint* ardour's stretch/shrink region edit-mode.
At least now it starts in sync but the
drift sets in after about 5 seconds.
What is the cause of this? Is the source material already out of sync
(eg. indepenent audio and video recordings)? Does it happen when cutting
the clips (in your case: after avidemux)? or is it a problem of the
final rendering/mastering?
A possible mistake could be that you simply specified a wrong framerate
or samplerate for the target.. (eg. you use 24fps source instead of
25fps?! or supplied an 44100 SPS audio to a PAL-DVD which should be in
48kSPS).
Maybe I could do it with liVES or
ffmpeg but I was surprised that none of the apps I tried offered
"Stretch" as a core feature/tool.
mencoder is your friend. It includes pullup and filmdint (inverse
telecine) filters; and it can do crude slow/fast motion via -fps , -ofps
That being said: you better fix the audio than tempering with video
framerates.
Through all of this process I have been consistently
amazed at the state
of Linux Multimedia apps. Maybe it's just my Fedora 10 64 bit system but
it seems to me that Linux Audio Apps are a good 5 years ahead of Linux
Multimedia.
yes, if not 10-15 years. While most core features have been present for
quite some time, there's a huge gap when it comes to interoperability,
usability and proper front-ends.
However I was glad to see that most of the apps had
JACK
support which made editing and listening a lot easier.
I still had to close all the apps occasionally because the fedora
mplayer doesn't have jack support and pulseaudio jack support isn't
obvious to setup.
have you tried `mplayer -ao jack <file>`
"Could not open/initialize audio device" ? -> recompile mplayer ;)
If the multimedia devs can get jack support right why
can't the pulse audio team?
I have a new level of respect for the amazing progress that Ardour
represents for Linux Audio and *cough*soon*cough* to be multimedia
(xjadeo). Ardour is without a doubt the most advanced and stable editing
system we have to work with.
I can see now that Ardour could well become the defacto "multimedia"
editing suite for Linux if work continues and we continue to support the
developers.
I would like to give cineFX (jahshaka) a shot too once I get the
openlibraries to install.
lumiera.org is on the horizon.
Cheers.
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