I was thinking of loading ”Lord of the Rings - Extended Editions” to my phone some time (after all, who does not need them in their phone?), but a little bit reluctant to upload 78 gb. So I decided to downsize them by ffmpeg, and realized that the audio bitrate was 1536 kb/s !
Seriously, one usually deals with audio bitrates of 128 kb/s, and 1536 kb/s is massive! I realized that it was partly because the audio was in 6.1 channels. Anyway, just reducing the audio will save me more than 7 gb’s. (I expect the video size to shrink for 15-20 gb’s as well)
Moral of the story? Keep LOTR in your phone, use ffmpeg (great libraries), and get rid of audio channels you cannot use!