Canon R5 and Transcoding

[thomatkinson]

Hi everyone, 

I'm trying to get my head around a workflow for shooting 4K video on a Canon R5 and looking for some technical advice. I'm on a 2020 iMac which is ok, and I'm using Premier Pro 22.2.0. I'm ultimately exporting for web - Vimeo, You Tube and Instagram mainly - and I'd like to retain as much quality as I can. 

I'm shooting C-log which, as I understand it, is H265 4.2.2 10 bit footage.  It looks great but it's a little slow to render sequences during editing and grading, and it's very, very slow to export. I've experimented with using proxies, which is fine but obviously the export times are still very slow. So now I'm looking at transcoding my H.265 footage to Pro Res 422 overnight before I start editing. I'm doing this via Project Settings > Ingest Settings. I'm finding this speeds up both sequence rendering and exporting but I'm not sure if I'm doing things in the right way and wanted to ask a few (mostly stupid...) questions:

- Why is there no option to transcode to ProRes 422 HQ - I understood that to be better?

- Is quality impacted by transcoding from H265 to ProRes422 (or ProRes422 HQ if it is an option)?

- My understanding is tha ProRes is a completely different codec to H265 - it is no longer H265 once transcoded to ProRes?

- After transcoding ProRes is my footage still 4.2.2 and 10 bit? 

- I'm exporting my finished videos to H.264 because that seems to be the most common requirement for web. Is there any reason I should export as ProRes422 HQ instead?

- If I upgrade to an M1 Mac in the future and have no problems with rendering and export times using H265 encoded footage straight from the camera, is there any reason to carry on transcoding to ProRes?

Thanks so much in advance - any help with these questions appreciated!

Thom 

[R Neil Haugen]

The ProRes codecs are alll 10-bit, except for the 4444 XQ which is 12-bit.

To ensure that, do check the Max Bit Depth options for encoding into it, as well as the Export dialog, scroll down and check the Render at Max Depth option, and set the little box to 16bpc. I didn't use to recommend that, but Jarle Leirpoll did extensive testing and says this is required to ensure full 10 bit on all files exported.

If you check the ProRes codecs stats online, the difference between say 422 and 422 HQ is bitrate. For 1080 timelines, 422 is around 145 Mbps, and 422 HQ is around 220 Mbps.

As ProRes is an intraframe codec ... meaning that all frames are complete in and of themselves, just compressed ... it is vastly easier for the computer to process on the fly, even though the file size on disc is greater. And yes, it is no longer stored in the H.264 compression after t-coding into ProRes.

H.264 is a normal delivery codec for many things these days. Some people do a ProRes or DNx export as a "master" of the project sequence, then make their H.264 deliverables from that file. Some just go with the direct H.264 from Premiere.

Another thing that is done is take the master file mentioned above, and go into ShutterEncouder or ffmpeg to make the H.2645 file, as those apps have a lot more options for H.264 encoding, especiall working quality against file size.

Also, t-codes for editing like this can be dumped after finishing the project, if you keep the names the same as the original file. As you archive the original H.264 small files, and can recreate the t-codes at any time if you need to come back to the project.

Neil

[thomatkinson]

Thanks for your reply - this is all very helpful. 

I’m still stuck on most of the questions in my post though - any help from anybody would be greatly appreciated! 

Thanks,

Thom

[Richard van den Boogaard]

I believe Neill has given you a pretty solid answer.

But okay, let me attempt to answer your questions specifically:

- Why is there no option to transcode to ProRes 422 HQ - I understood that to be better?

Using the Adobe Media Encoder you can encode/transcode the source footage to mostly any desired format before editing. So I don't see why ProRes 422 HQ would be impossible.

- Is quality impacted by transcoding from H265 to ProRes422 (or ProRes422 HQ if it is an option)?

Just like making a photocopy of pre-printed material, any transcode will result in some loss. A codec is there to keep the most essential information and throw away what is not essential, a process called compression.

- My understanding is tha ProRes is a completely different codec to H265 - it is no longer H265 once transcoded to ProRes?

No. Quicktime (ProRes) is an edit-friendly codec, whereas h.264 and h.265 are delivery codecs. What is strange, is that Canon has decided to go with a delivery codec for acquisition purposes in the R5 camera.

- After transcoding ProRes is my footage still 4.2.2 and 10 bit?

Yes ProRes 422 HQ is 10 bit. See details here: https://support.apple.com/en-us/HT202410

- I'm exporting my finished videos to H.264 because that seems to be the most common requirement for web. Is there any reason I should export as ProRes422 HQ instead?

Most social media platforms accept h.264 and some do support h.265 these days. Please bear in mind that the encoding engines have to deal with unimaginable amounts of data every minute of the day, so you can easily understand that they prefer an approach of "passing on a hot potatoe" instead of spending time to make your creation look like a masterpiece (which it undoubtedly deserves).

Also, they will re-encode no matter what you throw at them. My suggestion therefore, is to encode at higher bitrates and use either constant bit-rate or single pass encoding. Although dual-pass encoding results in a smaller file size (great for when your content is shown on a screen locally somewhere), that extra efficiently stored data in them bit reservoirs is simply ignored by the encoding lanes of social media.

- If I upgrade to an M1 Mac in the future and have no problems with rendering and export times using H265 encoded footage straight from the camera, is there any reason to carry on transcoding to ProRes?

No. The less transcoding (i.e. new copies) that are made in the workflow, the less degradation will result. Think of making a copy of a copy of a copy...

Hope this helps.

[R Neil Haugen]

Wonderfully informative post, Richard!

Neil

[thomatkinson]

Thanks Richard, that is enormously helpful.  

So, my takeaway from your advice and some tests, is that there is little point in me transcoding all my footage to ProRes 422 HQ before editing. While pre-transcoding to ProRes would give me potentially faster playback/timeline rendering during editing, and faster export times, it takes a very long time to transcode in the first place. As I'm having no serious problems with editing and only concerned with slow export times, it just comes down to a choice between a long pre-transcoding process before editing, vs a long export time after editing. There are no other advantages to pre-transcoding to ProRes in my situation and each time I transcode the file is degraded, therefore, I think I'll go with slow export times because pre-transcoding tons of footage, much of which I won't even use in editing, will take far longer than exporting the finished video. This has the added bonus of retaining as much quality as possible.

I do have one final question, if anyone knows the answer: 

Is there any advantage to exporting as ProRes422 HQ instead of H264? 

Thank you! 

[R Neil Haugen]

As to the latter question ... some people export to a "Master" file, in something like the ProRes 422HQ, and then make their H.264 deliverables from that.

Especially since Pr is great at the ProRes422HQ, and not so good at H.264. So taking the master file into HandBrake, ShutterEncoder, or ffmpeg then gets you more granular options for creating the H.264 files.

Neil

[thomatkinson]

Thanks Neil, that's a good idea. I'll try that too.

Thanks everyone!

[andrea_stewart]

Hi Neil. I'm curious, why Media Encoder isn't on y our list of compression software here. I would assume that the compression you get from Encoder would be the same as that directly out of Premiere.

[R Neil Haugen]

Me is the "full-bore" code of exporting that is also in Premiere. It's built around the sorts of options the engineers think are most useful in the majority of professional workflows. And by design does NOT include every option available in H.264/5 encoding. As there's a ton of things that can be done if you know what they are, and have all like 50 bazillion options available.

Handbrake and ShutterEncoder have more 'granular' options available. Se has a newer-look UI which will be easier for most users, I think.

ffmpeg is an open-source H.264/5 encoding app, and yes, it allows for EVERY freaking H.264/5 option that can be created. From what I've read, both Handbrake and ShutterEncoder are probably essentially front-ends for ffmpeg code.

I know quite a few users of ffmpeg, folks who've been in the video post life for years, and know the granular options they like or need to use. They've tried to convert me, but ... I've got other things for my brain to learn and absorb, thank you ... and ShutterEncoder does all I need.

Without learning a billion facts about H.264/5 encoding ...

Neil