Best format for archiving a sequence?

Report · Mar 02, 2018

I have a sequence that is composed of footage shot on a Sony A6300 in AVCHD format.

Footage is a combination of 4K and 2K, both 120fps and 24fps.

Final sequence is 1080p24.

What is the best export format to archive the sequence so as not to lose any quality?

The 1080p24 source footage shows as around 20mbps in Quicktime.

At Final Cut Pro 7 Professional Formats and Workflows I see that ProRes has the following bitrates for 1080p24:

ProRes 4444	ProRes 422 HQ	ProRes 422	ProRes 422 LT	ProRes 422 Proxy
264 mbps	176 mbps	117 mbps	82 mbps	36 mbps

Does this mean that 422 Proxy is adequate, since it's nearly double the source bitrate?

I tried exporting using the Video Preview format "I-Frame Only MPEG" with "Match Source" and "Use Previews" which resulted in an MPEG file with a 25 mbps bitrate; but looked noticeably worse than when exported using ProRes 422. So I'm confused.

Report · Mar 02, 2018

I frame only mpeg is a preview codec and of lesser quality and used in preview files:

The only time you use Preview files is when sequence codec is the same as the export codec.

I would go for Cineform 10 bit which you will find under Quicktime.

Report · Mar 02, 2018

I'm a fan of Cineform for Master files. They're as good as ProRes and cross-platform.

Report · Mar 02, 2018

I did some experiments...

I exported my (49 second) video using 4 codecs:

Cineform 10 bit YUV "3" aka "High" = 522 MB = 85 mbps
ProRes 422 = 683 MB = 111 mbps
ProRes LT = 493 MB = 80 mbps
MPEG I-Frame Only = 156 MB = 25 mbps

I then put each export on a new layer on top of my sequence, set its Opacity to Difference, and added an Adjustment layer with Gamma boost to bring out the differences.

I believe this allows to clearly see the differences in pixels between the export and the original sequence.

All of the formats above did show differences from the sequence, especially on high contrast edges.

The MPEG was the worst, obviously. The Cineform High and the ProRes LT were pretty much identical; if anything, the ProRes LT was a slightly better match. ProRes 422 was the best.

This seems to confirm that the bitrate is a pretty good indicator of quality.

I am going to also try ProRes HQ and Cineform levels 4 & 5.

Report · Mar 02, 2018

Cineform 10 bit YUV "3" aka "High" = 522 MB = 85 mbps

3 is actually Medium. 4 is High, and 5 is Best.