Converting from H.264 8bit to Hi10

[john157]

Hi I have some videos in H.264 8 bit and I would like to know how to convert it to H.264 10bit without loss.
Thanks

[aedipuss]

mediacoder can output hi10 but it's not lossless to re-encode anything.

[john157]

Would the quality of the video be the same, but the file size smaller if I were to convert an 8 bit h.264 to Hi10? What if I converted it the other way around?
Can I also know if there are other converters that can do this without changing the audio or subtitle files?

Thanks for your help

[aedipuss]

there are reported file size savings with hi10, but that when starting from an original file, not re-encoding an already existing h264 video. you can only make the quality worse with a second encoding at the same bitrate.