Hello, Bhikku. I'm still relatively new to these mailing lists, but I think I can help you out some.
My main observation is that you are doing 2-pass encoding using x264 for video compression. x264 has another variable bitrate mode called Constant Rate Factor. With this, you do not determine what your bitrate and therefore filesize is, but you determine overall quality. This means that videos with more motion will have much different compression than videos with mostly still motion. This is a variable bitrate mode but runs in a single pass. You can specify your max bitrates if you'd like, although a smaller sized video will automatically have a much lower bitrate at the same CRF. (more info: https://trac.ffmpeg.org/wiki/Encode/H.264#CBRConstantBitRate). Guessing a bit from your intended constant bitrates you mentioned before, here are some ideas on the CRF that'll get you started on this path: TV broadcast: crf 16 ffmpeg -i $file1.$ext -c:a libfaac -ab 128k -ac 2 -c:v libx264 -preset fast -crf 16 $file1.temp2.mp4 good internet: crf 20 normal quality: crf 22 low bandwidth: crf 26 tablet: crf 26 phone viewing: crf 30 (assuming these phones can playback MP4 files) That being said, if you'd prefer the control over bitrates, by all means use 2-pass encoding. In that case, I'd omit the "minrate" and "maxrate" options; you are specifying the average bitrate already so why constrain it to go within bitrates when you are doing a 2-pass encode on it in order to get the best quality per MB? Another observation is for your tablet and phone sections, your intended video bitrate is either comparable or lower than your audio bitrate: the audio bitrate of your "broadcast" and your "mobile phone" version are the same. The frequency rate is different, but the file size of the audio is the same. If you'd like to make it even smaller, you could get by with an audio bitrate of 64k or even less (based on how much you want to compress your video). One final observation: I personally would prefer keeping an original video for future editing if needed rather than a slightly transcoded version. I'm nit-pickey that way though. Why edit anything other than the best quality version you have access to, including the original format which you already have? Steve On Wed, Sep 3, 2014 at 5:08 AM, Bhikkhu Mettavihari <tv.li...@gmail.com> wrote: > > Greetings, > > We are compressing using ffmpeg and the following is our scripts > I would like to have your recommendations on this. > Technically it works OK, but your suggestions are very welcome. > My interest is to have your input on compression standards since the > world is changing so fast. > > In short we have these suggestions > > Mpeg2 for backup. > 3500K > 1024k > 512k > 268k > 130k > 038k > > with metta > Mettavihari _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
