they fail to apply, so instead of adapting them I just removed them for testing further ...
hm .....
~/cinelerra $ cat ~/storage/downloads/ffmpeg_8.diff | patch -p1
patching file cinelerra-5.1/cinelerra/bdwrite.C
patching file cinelerra-5.1/cinelerra/ffmpeg.C
Hunk #2 succeeded at 478 (offset 3 lines).
Hunk #3 succeeded at 1310 (offset 3 lines).
Hunk #4 succeeded at 1318 (offset 3 lines).
Hunk #5 succeeded at 1351 (offset 3 lines).
Hunk #6 succeeded at 1527 (offset 3 lines).
Hunk #7 succeeded at 3871 (offset 5 lines).
patching file cinelerra-5.1/cinelerra/fileac3.C