Red Hat Bugzilla – Bug 586069
png2theora works poorly with images with an alpha channel
Last modified: 2013-01-10 00:51:25 EST
Description of problem: png2theora creates poor quality videos when images are created with imagemagick. They have strange artifacts. Version-Release number of selected component (if applicable): theora-tools-1.1.0-1.fc12.x86_64 ImageMagick-6.5.4.7-3.fc12.x86_64 How reproducible: Every time via the following script. Steps to Reproduce: convert -size 640x480 xc:white -pointsize 32 -draw "text 10,40 'This is a test'" test_im.png for I in `seq 10 40`; do cp test_im.png $I.png; done png2theora %d.png -o test.ogg Actual results: The text "This is a test" has white for the color of the background, instead of black. This makes the text hard to see. Compare the text in the test_im.png and the test.ogg file. Expected results: The output should look more like the result of the next two commands: for I in [0-9]*.png; do echo $I; pngtopnm $I > /tmp/temp.pnm; pnmtopng /tmp/temp.pnm > p$I; rm -f /tmp/temp.pnm; done png2theora p%d.png -o ptest.ogg #In that case, the text looks fine. Additional info: I am not sure why this works when the pngtopnm/pnmtopng is done, but that fixes the problem. Either png2theora should warn about whatever feature imagemagick is using, or png2theora should output the correct result. This makes generating text for a video with imagemagick painful, because of the extra voodoo pnm step. Reported as distribution component since theora-tools does not seem to exist.
The problem with the images is the alpha channel. If it is removed, the images can be used fine. convert test_im.png -alpha off test_na.png Note that the file test_im.png is opaque everywhere, it just has a alpha channel that says that.
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Still occurs in: theora-tools-1.1.1-1.fc13.x86_64
Bumping version
This message is a reminder that Fedora 13 is nearing its end of life. Approximately 30 (thirty) days from now Fedora will stop maintaining and issuing updates for Fedora 13. It is Fedora's policy to close all bug reports from releases that are no longer maintained. At that time this bug will be closed as WONTFIX if it remains open with a Fedora 'version' of '13'. Package Maintainer: If you wish for this bug to remain open because you plan to fix it in a currently maintained version, simply change the 'version' to a later Fedora version prior to Fedora 13's end of life. Bug Reporter: Thank you for reporting this issue and we are sorry that we may not be able to fix it before Fedora 13 is end of life. If you would still like to see this bug fixed and are able to reproduce it against a later version of Fedora please change the 'version' of this bug to the applicable version. If you are unable to change the version, please add a comment here and someone will do it for you. Although we aim to fix as many bugs as possible during every release's lifetime, sometimes those efforts are overtaken by events. Often a more recent Fedora release includes newer upstream software that fixes bugs or makes them obsolete. The process we are following is described here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping
Seems to be fixed in Fedora 15.