On Friday 26 February 2016 10:42:14 pm you wrote: > Hi Carl, > > On Thu, 25 Feb 2016 13:55:52 +0100 Carl Eugen Hoyos <ceho...@ag.or.at> > > wrote: > > Hi! > > > > When encoding with FFmpeg, you can either use fixed quality or fixed > > bitrate (size), if you decide to use fixed bitrate, two-pass encoding > > improves the output quality. > > It makes no sense to use two-pass constant quality encoding, the result > > of using two contradicting options is undefined. > > > > Please close this ticket as invalid. > > I think if two options a contradicting then ffmpeg should refuse > accepting them instead of starting the conversion of the file. > IMHO this is a valid upstream bug, but upstream can decide to leave it > unfixed, of course. > > What do you think?
That my original comment was simply wrong. Using two-pass encoding for constant quality is not undefined behaviour, it works fine here with all native encoders I tested producing two identical output files. I don't think this should be changed: While it makes little sense, I don't think it is an issue that FFmpeg accepts two-pass constant quality encoding. When using libtheora, two-pass encoding only accepts constand bitrate, trying two-pass encoding with constant quality leads to an error. I believe this is exactly what you requested. Carl Eugen