There are several ways to patch/build, we'll do one pretty straightforward way.
Will be done in the same terminal but will be a couple of times when you'll need to browse to the build/source folder to do something, so when that happens leave the terminal open, that way you'll be at proper prompt for next command
The build will take a while, just let it go. It runs some tests, 1 will fail, doesn't matter, quite expected.
This is 1 optional thing - you can either build to the exact same package version as is now in 12.04 or slightly up the version. If leaving the changelog as is then you'll need to be careful not to upgrade back, a repo package is always seen as upgradeable over the same local built one.
By adding a +nmu1 to package version it won't upgrade until the repo package goes to next version, (if it ever does..
So follow carefully, should be easy, will post some screens to refer to if need be
Open a terminal -
mkdir -p gstbad_build && cd gstbad_build
When that successfully completes then continue, if any issue resolve first
sudo apt-get build-dep gst-plugins-bad0.10
Now download the attached patch, (r, click > 'save link as'), extract, open the folder & place both files in ~/gstbad_build/gst-plugins-bad0.10-0.10.22.3/debian/patches. You'll be replacing the 'series' file & adding the h264parse.patch file , see screen 1
apt-get source gst-plugins-bad0.10 && \
While in the source folder for above open /debian/changelog. Just append a +nmu1 to (0.10.22.3-2ubuntu2) as seen in screen 2, save & close text editor
(this isn't a 100% proper edit, doesn't matter as you're only building for yourself, not publishing
Back at the terminal
Should show this -
If so then
:~/gstbad_build/gst-plugins-bad0.10-0.10.22.3$ dpkg-source --commit
dpkg-source: info: patches are not applied, applying them now
dpkg-source: info: applying h264parse.patch
dpkg-source: info: there are no local changes to record
When build completes (hopefully, see screen 3), then
dpkg-buildpackage -rfakeroot -D -us -uc
Leaving terminal open at the in prompt, move just 2 packages into the in folder - screen 4
mkdir ../in && cd ../in
Finish up at the terminal with
Any issue let me know, just remember to leave the same terminal open from start to finish