Originally Posted by lew
Now I have to try to see how small I can get the file. The ff defaults on KMTTG and VRD both give me a file of about the same size, bitrate about 2500. Is that about as small as you can go and still get a video worth watching?
FWIW I'm using the iPad3.
It sort of depends on what your original video was that you are coming from (mainly whether SD or HD and broadcast bitrate) and how much effort you are willing to put into your conversion process.
The most successful way to reduce the filesize is to edit out the commercials (enter VRD). You have VRD, but I am not sure if you edit out commercials or not.
The next best way to reduce filesize is reduce the target bitrate, for SD video I frequently transcode with final bitrates around 1000-1200 kbps.
Other ways to reduce filesize is to remove the duplicate frames or telecined frames or apply some denoiser to the video. I do this with avisynth. It can also be done with Handbrake (at least telecined frames can and rudimentary denoising).
If you already edit out commercials before transcoding, then you can try the kmttg profile called hb_tivo_sd_crf. This is a handbrake profile that transcodes using a constant rate factor of 19 (which I find to be transparent visually for SD video), inverse telecines the video and applies a very light denoiser. Compare that to the ffmpeg output and see if that meets your need.
For HD video, shrinking filesize can also be accomplished with resolution change as well as duplicate/telecined frame removal and denoising. The hb_tivo_hd_crf profile in kmttg is similar to the sd profile, but with the rate factor set to 21 rather than 19 (which seems transparent to me for HD video). It also is set up to inverse telecine video. I haven't actually used handbrake for transcoding for a number of years now, so I am not sure how successful it will be at removing telecined/duplicate frames for HD material. (1080i material is broadcast as hard telecined video, while 720p is broadcast as 3:2:3:2 full frame dups of the original video.)
This profile does not reduce resolution. I also use avisynth for this. I take all my HD video and output as 720p24*.
Anyhow, you should be able to drop the bitrate further and still have great looking video. Going the avisynth route is not what anyone would consider easy/quick, so I am not going to go into what all is entailed. Kevin also has some handbrake profiles that do adjust resolution (iphone/ipod/psp). You could use one of those and maybe one of the crf profiles to come up with a reduced resolution version with constant rate factor and inverse telecining.
Constant rate factor is a quality based transcoding algorithm that x264 (h.264 transcoding engine behind handbrake) uses to output video as a given quality level. The final bitrate will vary based on the source video. Broadcast television tends to have relatively low quality video already, so your final bitrate for that will be lower than for a blu-ray source at the same CRF number. You can adjust constant rate factor to hit the quality level you want. I would stay between 16 and 23 (the lower the number, the higher the bitrate). It is a float, so you can use decimals as well.
*except sports and UK sources