Codecs

Apple ProRes 422 HQ

The video lab intends to use Apple ProRes 422 HQ as an archiving codec. According to Apple, the nominal data rate is 220Mbps for 1920x1080 at 29.97fps. (i.e.773 GB/hour or 0.756 TB/hour).

A sample from Kikani's DeepPIV video was recorded using 422 HQ at 60fps. Her video was 457.68 GB at 8441.233 seconds long (2h 20m). Her data rate was 55.52 Mbps for 1920x1080 at 60fps (195.19 GB/hour (0.19 TB/hour)

h264

Transcoding to h264/mp4

Prores can be transcoded to h264 using ffmpeg. Here's an example:

# Using default encodings
ffmpeg -i SC1ATK52.mov -c:v libx264 -movflags +faststart -c:a copy ~/Desktop/SC1ATK52-h264.mp4
# Using higher quality (crf=10 preset=slow)
ffmpeg -i SC1ATK52.mov -crf 10 -preset slow -c:v libx264 -movflags +faststart -c:a copy ~/Desktop/SC1ATK52-h264.mp4

The audio track is just copied over to the new container and the headers are added to the front of the file for web playback (i.e. faststart). Note that the default encoding is ran in my test (source prores on
Atlas, target file on my laptop) at about 10fps. That means the transcoding would take 505968 frames / 10 fps / 60 s per m / 60 m per h = 14 hours, the higher quality one at 3fps (46 hours)

Examining a File

First install ffmpeg. On Mac, you can use homebrew. Here's the command to install it with reasonable codec support:

brew install ffmpeg --with-faac --with-libvpx --with-openjpeg --with-schroedinger --with-theora --with-x265

You can then use ffprobe to examine the contents:

ffprobe -v quiet -show_streams -show_format -show_error -print_format json h265_test.mp4