How many generations of .mp4 till quality degrades?

Report · Mar 30, 2018

I did some tests by taking a .mts avhcd clip and exporting it out to .mp4 with the H264 setting and moved the target and maximum bitrate sliders all the way up. I exported this and put the clip above my .mts clip in premiere and zoomed into 100 percent in the program monitor and turned on and off the video track for the mp4 clip and found no quality difference at all from the .mts avchd clip. I then added a few lumetri color settings and even scaled the clip itself to make it extreme. I exported the .mp4 again with the scale and lumetri color settings to another h264 .mp4 file with the same settings as before in the export window. Low and behold no quality degradation in premiere from the first .mp4 clip.

Question is this. how many more times can I seriously keep exporting a .mp4 clip before degration occurs? Since it appears I can at least export once if not twice from .mp4 I see no reason why I can't convert my AVCHD clips to .mp4 and edit with those which would enable me to label my clips in windows explorer and not have to deal the card structure of the AVCHD files. I do not like it when the clips are unnamed and I can't rename them or the card structure gets broken but if I have .mp4 clips it's easier.

Am I right to assume AVCHD is h264 anyway?

Report · Apr 01, 2018

What's interesting is I did another test by using a USB 3 external HDD with cineform quality 4. Plays in fine as long as I put the project file and cache on the 1TB SSD.

By the way I have always heard raid 0 is not good for video and it one drive fails you lose all the data. Also is there even a raid external that allows 4 1TB external drives?

Report · Apr 01, 2018

bryced87 wrote
By the way I have always heard raid 0 is not good for video and it one drive fails you lose all the data. Also is there even a raid external that allows 4 1TB external drives?

Yes, RAID0 is for when speed is the priority and once upon a time it was a must have for any video work. Now it's required for very high-end work, but not general editing. You could go with a RAID0+1 configuration so that it's striped for speed and then mirrored for backup. This can be a multi-bay unit that does this or done manually with two RAID0s (one for primary storage and one as a cloned backup). USB3 , USBC and eSATA tend to work well enough for 1920x1080 workflows and 3840x2160 HighResolution/Proxy workflows. If more speed is needed, there's always Thunderbolt if you motherboard has the connector. Even with stand alone drives, I always buy storage in pairs. So, I'd buy two 2TB USB3 mobile drives configuring one as the primary storage and the other as the backup (I use Carbon Copy Cloner, but there's EaseUS, SuperDuper, Acronis TrueImage, and others).

A thing to remember about RAID1 and RAID5 is that while they protect against a drive failure, they don't protect against directory corruption or file corruption. So, even your RAID storage should be backed up to other storage.

Report · Apr 01, 2018

I did discover if I change the aspect ratio to SD I can make a SD cineform file as a proxy. I can get the proxy file size around 1gig. This then can be used on an SSD with the original high quality cineform version on an HDD.

Report · Apr 03, 2018

Maybe I should just create cineform when I really need it like when I need export an effect into a new clip etc and just use the regular native media?

Report · Mar 31, 2018

Silly question. what if I say exported the AVCHD files as Cineform 4 setting then once they were in Cineform I took those files and exported to .mp4 and edited those? Would it somehow treat the .mp4 as higher quality files as if I had recorded in that format? Cineform is supposed to retain the quality so I would think if I went to Cineform first then back into .mp4 it should be closer to the same quality as original avchd footage.

I'm not seeing how 24mbps .mp4 or AVCHD is that good for grading anyway and even though Cineform would be a larger file and it would mantain the quality I won't get anything extra out of those files since it was still recorded in 8 bit color mode. I just would have an easier format to playback in premiere.

Report · Mar 31, 2018

okay I just realized that if I put the SDHC card back into my canon camera I have an option in the camera to convert AVCHD to MP4. Does that lower the quality or do you think if it is doing it inside the camera it maintains the quality?

Report · Mar 31, 2018

if the camera sensor debayer is 8 bit, getting a 10 bit recorder is a waste of time.

there's some cameras that can output 10 bits if using an external device as it bypasses the h.264 compression.

the only advantage to recording first avchd, then cineform, then finally mp4 would be if you needed to

change the gamme in between avchd and cineform as it would hold the gamma change in 10 bits so you could

recover it later. anything else would be a waste of space.

cineform won't make stuff look better. it just holds

noise removal, major gamma grading that you can undo later, and smooth playback. that's it.

Report · Mar 31, 2018

not sure about the sensor on my camera but the canon xa25 manual says SDI output is 10 bit and the sensor in the manual is listed as 4:22 but someone else online on a canon form seems to think it records in true 10 bit if you use an external recorder via SDI output