I don’t know what SamX uses for a decoder, Reaper can use Quicktime or VLC. What does Ardour use? Is this customisable and does it even support MP4?
Ah its no MP4, its AVI. Nevermind my comment.
Not a pb, i’ll try again another day. Ardour4 is a great daw, but not for video post synchro for the moment.
I would recommend you look through my comment again, as I mentioned above, you can tell Ardour NOT to transcode a preview version (It is in the settings, either when you ‘Open Video’ or in the preferences for Ardour, can’t remember where) if you are comfortable with that, and instead use the exact file you give it. This is not the default, because when you are doing video post, it wouldn’t be unusual to end up with HUGE track counts, where every bit of performance on the computer can help and losing, which is one reason why transcoding is default in Ardour. And then when you export from Ardour you can tell it to export using the original media instead of the transcoded preview so that there is no difference in exported quality.
I have used Ardour a LOT for video post honestly, and Ardour4 is very good for this in all honesty, at least for what I am concentrated on (Dialog and SFX with using music someone else writes).
SeabladeWAit 
tried and tried and tried again, and it depends of file. It’s only a codec problem.
Hurrah.
I can open and transcode some video files on Ardour4 and it works perfectly. Some of them cannot be opened on ardour4.
Ok seablade thank you. It’s only a pb of codecs, i’ll do more beta testing and I will give all details on forum. (Ardour4 on Windows 8.1 pro)
Ardour 4.0.397 (ancient nightly build) works perfectly. I can open audio AND video files, I can extract audio from video; I have video timeline etc.
Ardour 4.0-415 (02.06.2015 version) doesn’t work and crashes everytime i try to open video files…
SO if you can fix it once for all, Ardour4 will be one of the best DAW on the market. Stable, Midi and audio, Aui Vsti Ladspa, multicore, 64bits, for Linux Mac os X and Windows 
CPascal can you post an issue to Mantis for the devs? Click on the bug tracker link at the top, and include the details about the videos you tried as well as the versions that worked and the ones that didn’t. Thanks.
SeabladeOf course.
done
HI seablade. Tried several (1 hundred times :)) ? with all my computers) and I think I found the cause of this problem.
When I record Ardour4 Sessions on USB external HD I obtain video and timeline but never audio extraction. USB external HD is too low
I tried again but on internal HD and it simply works on my 2 PCs.
For audio sessions we can use Ardour4 serssions on external HD
For video syncro we must have internal HD or very fast HD
Tried 5 min ago with a HUGE video file and it works
Resolved/ Closed.
sorry for any convenience.
Resolved/ Closed.
sorry for any inconvenience.
No more crashes (fixed with new nightly builds) and no audio extraction pb (resolved)
best regards
Thanks for the report. No need to resolve/close things in the forum, that is why we ask people to submit bug reports so that we can keep track of them. On the forum they just get lost because they aren’t kept track of in the same way:)
Odd that it won’t work on the external, I assume this is still happening for you?
Seabladeokay. I can’t extract audio when i record ardour sessions on external USB HD. I tried with all the USB HD I own, doesn’t work.
but works with internal HD even with huge video files. I suggest, for windows, internal HD only for data.
Ok that suggests a bug in Ardour on Windows somewhere I believe. Any chance you can submit that on Mantis (The Bug Tracker link at the top of the page) so that the appropriate dev can take a look at it?
SeabladeIt’s the report n° 006366
Thanks!
Seablade