Re: Making videos with jack and a webcam or something else, band recording.

Jorge Salgueiro <jorge.salgueiro@xxxxxxxxx> · Sun, 9 May 2010 20:43:19 +0200

for me to record a music video I would:
- buy a Canon 550d (t2i) and record at 25p (or 24p -24 progressive frames - if you are from the states) recording the sound with the camera 
- at the same time record sound with a jackd 

- use kdenlive to transcode video to dnxhd
- in kdenlive, sync the camera sound with the master from the jackd app
- delete camera sound, and render the final video.

(use a gooooooooood PC if you doin' full HD recordings)

Atentamente,     Jorge Salgueiro (Incitec S.L.)
______________________________________
Use GNU/Linux: free culture for a free society

2010/5/9 Niels Mayer <nielsmayer@xxxxxxxxx>

[[resending to list as it bounced the first time due to >30K length]]

Loki Davison <loki.davison@xxxxxxxxx>:

digital camera then try and sync the audio afterwards or what? What video recording apps work with jack?

One simple possibility: use whatever you'd use to record and transfer video into mp4/etc and then use xjadeo/qjadeo for playback sync'd with an external sequencer/daw. (I use the one from PlanetCCRMA: http://ccrma.stanford.edu/planetccrma/mirror/fedora/linux/planetccrma/12/i386/repoview/xjadeo.html 

http://ccrma.stanford.edu/planetccrma/mirror/fedora/linux/planetccrma/12/x86_64/repoview/xjadeo.html )

Installed Packages

Name       : xjadeo

Arch       : x86_64

Version    : 0.4.7

Release    : 1.svn200.fc12.ccrma

Size       : 356 k

Repo       : installed

>From repo  : /xjadeo-0.4.7-1.svn200.fc12.ccrma.x86_64

Summary    : Very simple video player that gets sync from Jack

URL        : http://sourceforge.net/projects/xjadeo

License    : GPL

Description: Xjadeo is a very simple video player that gets sync from jack. When

           : a sequencer like Muse or Rosegarden acts as a timebase master,

           : xjadeo will display the video frame in sync with the sequencer

           : transport. This means that you can visually synchronize an audio

           : event with a certain frame in the movie, which comes quite handy

           : when you want to create a soundtrack for a video clip.

> rpm -ql xjadeo

/usr/bin/qjadeo

/usr/bin/xjadeo

/usr/bin/xjinfo

/usr/bin/xjremote

/usr/share/doc/xjadeo-0.4.7

/usr/share/doc/xjadeo-0.4.7/AUTHORS

/usr/share/doc/xjadeo-0.4.7/COPYING

/usr/share/doc/xjadeo-0.4.7/ChangeLog

/usr/share/doc/xjadeo-0.4.7/NEWS

/usr/share/doc/xjadeo-0.4.7/README

/usr/share/doc/xjadeo-0.4.7/TODO

/usr/share/man/man1/qjadeo.1.gz

/usr/share/man/man1/xjadeo.1.gz

/usr/share/man/man1/xjinfo.1.gz

/usr/share/man/man1/xjremote.1.gz

/usr/share/qjadeo/locale/qjadeo_fr.qm

One potential issue w/ xjadeo is that it appears to puke on some HD content that ffmpeg-based playback has no problem with. For example when I record off digital cable, it fails to recognize or read the files, even though ffmpeg says they're "ok" (modulo "Seems stream 0 codec frame rate differs from container frame rate: 59.94 (60000/1001) -> 29.97 (30000/1001)" and "Seems stream 2 codec frame rate differs from container frame rate: inf (1/0) -> -nan (0/0)" :-) ).... Transcoding "off the air" files recorded in, e.g. mythtv, fixes the issue:

> xjinfo Videos/India_Music_Voyager_PBS.mpg

Videos/India_Music_Voyager_PBS.mpg: Error while opening file

> ffmpeg -i Videos/India_Music_Voyager_PBS.mpg

  built on Nov  7 2009 10:57:27 with gcc 4.4.2 20091027 (Red Hat 4.4.2-7)

  ...

Seems stream 0 codec frame rate differs from container frame rate: 59.94 (60000/1001) -> 29.97 (30000/1001)

Seems stream 2 codec frame rate differs from container frame rate: inf (1/0) -> -nan (0/0)

Input #0, mpegts, from 'Videos/India_Music_Voyager_PBS.mpg':

  Duration: 00:27:50.47, start: 34145.227389, bitrate: 3363 kb/s

  Program 1 

    Stream #0.0[0x940]: Video: mpeg2video, yuv420p, 544x480 [PAR 20:17 DAR 4:3], 15000 kb/s, 29.97 tbr, 90k tbn, 59.94 tbc

    Stream #0.1[0x941](eng): Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s

    Stream #0.2[0x9c0]: Video: mpeg2video, 90k tbn

    Stream #0.3[0x9c1](spa): Audio: ac3, 0 channels, s16

It happily decodes just about everything else, and its 'xjinfo' utility gives me some useful XML to boot:

Niels
http://nielsmayer.com

PS: speaking of extracting structured information from videos && before i have to cobble together my own: does anybody know of a lib that extracts captions and caption-timing information from videos and outputs some nice structured output (e.g. timedtext, SMIL)?? And also the same API should transparently allow access to YouTube's Google-voice-based automatic caption extractor ( http://www.digitaltrends.com/computing/software-computing/youtube-opens-automatic-captioning-to-everyone/ ... http://code.google.com/apis/youtube/2.0/developers_guide_protocol_captions.html ) Even if it's imprecise/hilarious, it's also a giant onset-detection corpora for a good portion of the internet's video. :-)

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