low image quality when grabbing with dvgrab

Bug #859108 reported by Raffaella Traniello on 2011-09-25
12
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Linux Stopmotion
High
Unassigned
dvgrab (Ubuntu)
Undecided
Unassigned

Bug Description

When grabbing with dvgrab from a MiniDV camcorder the image has unacceptably low quality (horizontal artefacts).

Changed in lsm:
importance: Undecided → High

Herman Robak found out that the problem is not the JPEG encoding. It's the DV decoding by dvgrab.
In dvframe.cc (dvgrab code) the "quality" is not set to "best".

decoder->quality = DV_QUALITY_COLOR | DV_QUALITY_AC_1;

Should be:

decoder->quality = DV_QUALITY_COLOR | DV_QUALITY_AC_2;

If dvgrab is modified and recompiled, then the grabbing maintains the DV quality.

Changed in lsm:
status: New → In Progress

dvgrab website: http://www.kinodv.org
dvgrab source code: http://prdownloads.sourceforge.net/kino/dvgrab-3.5.tar.gz?download
Patch to dvgrab by Herman Robak: http://odin.s0.no/rot/sol/dvgrab_fix-jpeg-quality.patch
Package of patched dvgrab by Odin Omdal (use at your own risk): http://odin.s0.no/rot/sol/dvgrab_3.5-1_i386.deb

Dan Dennedy (dan-dennedy) wrote :

Hi guys, I seem to recall I had set it to this lower quality for speed and because I was recommending most users users quarter resolution with the -jpeg-deinterlace option to get rid of interlace motion artifacts in web cam scenarios. At the time the code was introduced the modern PC running libdv or ffmpeg was just able to decode best quality DV full frame rate in realtime! Obviously, that does not make sense anymore and especially for stopmotion work. So, I will change it now in dvgrab svn, but I do not have any imminent plans to make a new dvgrab release.
The change is now committed to dvgrab svn rev 1464.

Changed in lsm:
status: In Progress → Fix Committed

Thanks Dan!

I'll add some info for reference:

Browse the dvgrab SVN repo at: http://kino.svn.sourceforge.net/viewvc/kino/trunk/dvgrab/
At the bottom of that page you can find a "Download GNU tarball" link. To use the source code you have to extract the folder from the archive first.

Alternatively, to download the dvgrab source code from a terminal, type:
    svn co https://kino.svn.sourceforge.net/svnroot/kino/trunk/dvgrab dvgrab

To compile dvgrab from source, copy and paste the following terminal commands, one a the time:

   cd dvgrab
   ./configure
   make
   make install

The attachment "dvgrab patch by Herman Robak" of this bug report has been identified as being a patch. The ubuntu-reviewers team has been subscribed to the bug report so that they can review the patch. In the event that this is in fact not a patch you can resolve this situation by removing the tag 'patch' from the bug report and editing the attachment so that it is not flagged as a patch. Additionally, if you are member of the ubuntu-sponsors please also unsubscribe the team from this bug report.

[This is an automated message performed by a Launchpad user owned by Brian Murray. Please contact him regarding any issues with the action taken in this bug report.]

tags: added: patch
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