panamajim 5 Posted October 28, 2016 Share Posted October 28, 2016 I have Emby installed on Ubuntu 16.04 and Windows 10. I've been working through different issues on each platform and for about two weeks now I've had both installations recording the same TV programs. The hardware platforms and OSes are different but the settings within Emby are the same. More importantly, both installations run the same version of ffmpeg. I've noticed that for any particular recording the final file size on Windows is almost always smaller than the Ubuntu version. In most cases the file size is between maybe 5 to 10 percent smaller, in other cases I've seen the Windows recording be almost 40 percent smaller. Has anyone else encountered this? What causes the differences in sizes? If I'm using the same version of ffmpeg on both systems wouldn't the final product be the same size? Link to comment Share on other sites More sharing options...
Luke 36990 Posted October 28, 2016 Share Posted October 28, 2016 We'd have to look at a specific example. It's possible the encoders themselves may have code that varies per platform. But most importantly, it's not really an equal comparison unless the content is exactly the same. Is it? Link to comment Share on other sites More sharing options...
panamajim 5 Posted October 28, 2016 Author Share Posted October 28, 2016 Luke, even with the highest precision commercial clocks installed on both computers it would be impossible to have "exactly" the same content on both systems. That said, they both record the same stream from the HDHomeRun and they both start/stop at the same times. I'm sure there's a minor variation in clocks between the systems as I haven't pinned either to a NTP source for time updates but within those parameters I'd say yeah, the content is the same. The Windows system is significantly beefier, i7-4770k with 32 GB RAM and two GTX 960s while the Linux box is an AMD 955 Black with 16 GB RAM and an old ATI video card. Still, both systems have no issues transcoding on the fly so I think the hardware differences would be a wash. My guess is that the Windows codec may be more efficient due to build options but.... *shrug* I don't know. Link to comment Share on other sites More sharing options...
Luke 36990 Posted October 28, 2016 Share Posted October 28, 2016 that's possible, yes. Link to comment Share on other sites More sharing options...
panamajim 5 Posted October 28, 2016 Author Share Posted October 28, 2016 I'll buy that for a dollar. Link to comment Share on other sites More sharing options...
Andy777 21 Posted October 28, 2016 Share Posted October 28, 2016 In addition to the build options (and different compilers on different OS platforms), the ffmpeg also has multiple runtime optimizations that depends on the cpu of the system it runs. Also the external libraries used (when compiling) could be different versions (e.g.x264). 40% difference (if the file is large) sounds a bit too large though to be caused by these. BR, Andy777 Link to comment Share on other sites More sharing options...
Luke 36990 Posted October 28, 2016 Share Posted October 28, 2016 Good info, thanks! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now