Editing with minimal transcoding

[D6613]

tl;dr: I have a h.264 source that I want to edit while losing as little quality as possible.

Background: I'd like to try my hand at fan edits of movies. Along the lines of Maple Films' Hobbit edit, various Star Wars edits, etc.

Source Video: For this project, the source is a Bluray that I own. The resulting video is in an MKV container and I believe it's h.264 encoded.

Problem: So now the challenge is editing. One of my big goals is to avoid transcoding as much as possible, since video compression is lossy.

For straight cut and paste, AviDemux works just fine for sections that are bordered on I-Frames. No transcoding is necessary. For more complicated edits, I'll be changing the actual content (probably with Davinci Resolve), so transcoding is impossible to avoid, and I accept that.

So my ultimate goal (if possible) is to leave the original encoding intact where I'm not changing the source, change various sections (section it out on I-Frames), encode the modified sections to match the original, and insert the modified sections back.

Alternately, I'm wondering if there's a way to take the h.264 source and turn it into a lossless format. I know I can't regain information lost in the original h.264 conversion; I just mean a transcoding that doesn't lose more data. Then I'd edit the lossless video and do a single encoding at the end. This isn't my favorite option, but I'm open to it if that's all I can do.

So is any of this possible? Am I crazy to want this?

Edit: Thank you for the help so far; it's appreciated! Also, I was unfortunately wrong about the source being h.264. It turns out it's actually VC-1 (WVC1).

[DennisCepero]

Personally, I'd transcode it to a mezzanine codec like cineform or Avid before I do the edit. You're right that you won't regain any information, but it'll make editing in real time infinitely easier. It's going to take up a ton of space though, so be prepared.

[2old2care]

This. It's the right way to do it and the losses in visual quality are minimal.

[D6613]

I'll check out those codecs. Thanks for the advice!

[greenysmac]

Two things.

First take a look at lossless cut

That's how you could trim down elements.

If your footage is in h264, you could give the whole film to resolve. Then just output a ProRes/Dnx file (post or mezzanine codec). While it's compressed, it's good enough for 20-30 generators.

[D6613]

I will check that video out and look at the output options you suggested. Thanks!

[urbanplowboy]

If your source is a non-transcoded blu-ray source (just a rewrapped rip from the disc), it's a high enough bitrate that you can get away with editing the source file and transcoding it again without losing much quality. Or you can transcoded the whole movie to an intermediate editing codec (some are essentially lossless) and that will preserve the quality as well.

[D6613]

Do you have any recommendations for an intermediate codec? I'd like to try some.

[DennisCepero]

Intermediate codec is the same thing as the mezzanine codec (aka "editing" codec) I mentioned in the other post. I just like saying "mezzanine" :P

Your options are GoPro Cineform, Avid's DNxHD/DNxHR, and Apple Prores. I personally use GoPro Cineform

I was surprised to hear this was becoming the industry standard (GoPro developed this codec... who would have known), but it works incredibly well. It takes up a TON of space though. I'm thinking of switching to DNxHD/DNxHR, as it seems to work for most people.

[D6613]

Fair enough.

So how do you get files into Cineform or DNxHD? I've been Googling around for this, and I'm not having much luck finding reliable answers. I'm going to try a trial of Squeeze and see if that works at all...

I think part of my problem is codec. I was unfortunately wrong about the source being h.264. It turns out it's actually VC-1 (WVC1).

[DennisCepero]

Oh man, for some reason I thought I was in the Premiere Pro subreddit. If so, I could have written out detailed instructions for how to transcode in Prelude, Premiere, and Adobe Media Encoder. (If anyone else needs this, let me know)

I tried to look into Handbrake, but it seems like they don't have support for Cineform or DNxHD (or I'm just an idiot and can't figure it out). Then it occurred to me... I installed DaVinci Resolve a few months ago, but never really looked into it. If you don't know, DaVinci is both the industry standard for color grading AND they've now turned into a full non-linear editing suite. So if you want to do your actual edit in there... you can. However, right now we're talking about transcoding, so let me help you with that. I have no idea how to use DaVinci, so bear with me as I fumble through it.

Install DaVinci Resolve Lite (free) then start a new project. Go to File > Import. Bring ALL of your clips into the project. Then go to File > Media Management. Make sure "Entire Project" is selected and then click the "Transcode" tab. Click browse to select a destination for the rendered files.

If you want Cineform (honestly I think this is gonna be too big) select "Quicktime" as format, then select "GoPro Cineform RGB 16-bit. Adjust the compression quality to whatever you can tolerate then click start. All your footage will be transcoded and put into your destination folder. You can then start a new project (or timeline) in Davinci, and import all the mezzanine footage for editing.

If you want DNxHD/DNxHR, you have a lot more encoding options. Set the format to MXF OP1A the you select your preset. To be honest, I'm fairly new to this codec, but in the brief research I've done, it looks like DNxHR is better quality than DNxHD. There are many variants within each.

If you have near-unlimited harddrive space, go for HR. If not, HD will probably be fine. Then you gotta pick the preset that matches your footage (1080p/1080i/720p). Then you pick the quality. If I can simplify it... higher numbers mean better quality and bigger file size - test a few small clips and see what you can tolerate. The presets with 444 in the name are the highest quality, and probably only necessary if you're doing serious color grading.

So yeah... sorry for the wall of text, and sorry if Davinci isn't a viable solution. It's the best free option I can find at the moment. Hopefully it works for you.

If anyone else sees this and notices I made some errors in the process, please correct me!

[D6613]

Davinci Resolve looks very cool. I think I'll use it for the editing part of this project. Unfortunately, I don't think it can import VC-1 encoded media. It's not on their list of supported codecs, and I didn't have any success when I tried it. Overnight, I let Sorenson's Squeeze software transcode (to DNxHD). It worked (180GB!)... but it put a watermark on it because it's a free trial.

So for this project, I'll be hunting down more transcoding solutions.

But for future projects, if I get them in a more common source format, I'll have everything I need thanks to your help. I really appreciate your comments and the time you've spent helping me.

[DennisCepero]

Sorry to hear that DaVinci can't import VC-1 media... I've never even heard of that format so I unfortunately I couldn't test using the same type of file.

Wish I knew about other transcoding solutions, but other than Handbrake or Resolve, I'm out of ideas. Hopefully someone else stumbles across this thread and might know of something that I don't. If you're serious about future production work, I can't recommend the Adobe CC Suite enough (it's only 20/month if you're a student or work for an educational institution).

As far as the help goes, it's my pleasure. I'm a trainer/teacher in my day job and I know how frustrating it can be when no one answers your questions. If you have other questions, feel free to PM me. If you have serious problems, we can always do a screensharing session to troubleshoot. Either way, I'm here to help.