Just compressing some files with MediaCoder and did some reading and looking at the various options. MediaCoder is a front end for the various opensource and free solutions that have emerged over the years. Have settled on the following settings after comparing various options:
Container: MP4
Audio: AAC seems better than MP3 for high compression (<44kbps variable). But >77kbps, variable, AAC versions 2 is worse than version 1 and as compression is reduced quality doesn’t increase much for either so MP3 becomes the favoured compression.
Conclusion:
For low quality TV storing am using HE-AAC V2 (Nero Encoding). Quality=15. 32kbps (voice). 44.1kHz sampling - seems to affect quality a lot if lower.
For movies MP3 (LAME), 112 Average Bit Rate i.e. cassette quality (CBR is pointless!). Original sampling.
Video: have settled on XviD (opensource version of DivX) Advanced Simple Profile Level 5 for phone, and H.264 for movie.
Conclusion:
Movie Video Quality: 90 halves video size.
Phone Quality: 80 seems to provide good quality and less than 1/4 size.
If interlaced (i.e. TV format) needs to be converted to progressive to aid compression codecs. This has bonus of removing some unneeded frames too. (Interlacing refreshes the screen in alternating lines so frames come in pairs called fields, these pairs are combined into single frames for progressive.)
Frame rate: the phone is 15fps. For movies and long video keeping original as low frame rate is tiring on eyes.
Aspect Ratio (AR). The phone is 320x240 pixels (4:3). Set Display AR for phone 4:3 but without crop squishes the picture but is watchable.
No comments:
Post a Comment