Why use Apple Prores over Apple Intermediate for GH1 / 5D footage.

[Drcoffee]

Hi Guys, Does someone have a definitive reasons why to use Apple Prores over Apple Intermediate codec for GH1 / 5D footage ingested into FCP?

I've done several heavy grading tests and can't find any difference except Prores is twice the file size...? Does anyone have any side by side comparisons?

Kind Regards, and thanks for any advice in advance.

Jon

 

[noam]

Jon,

You're right.. to the eye there doesn't seem to be much difference between the two codecs.. From my experience working at an on-lining facility - we always used ProRes. In many cases we likely could have gotten away with using other codecs but ProRes really seems to hold up the best, especially if you are compressing and recompressing the footage with different software. I've found after footage has been compressed more than once, the ProRes codec always holds up better.

With that said, I've had a few nightmares working with ProRes and the 5D. My biggest issue with 5D footage is that it can change so drastically upon final export with ProRes. I just worked on a huge corporate project recently that was shot on the 5D and it was a nightmare to color correct (because it was shot WAY to warm). Once it was all ready for final export, ProRes seemed to make the image significantly darker and higher contrast. I ended up having to export an H.264 instead. This is unusal though.. As I mentioned, I worked at an on-line facility for some time and we regularly worked with 5D footage on many national television shows, with no issue. I've found that as long as the footage is shot properly - you're relatively safe. Once you have to do any heavy grading, 5D and ProRes seem to be a bad match for some reason..

 

[diegocervo]

Noam,
did you work on fcp or AP for that project? I always had issues when doing color correction in fcp. Rendered files processed in Color and imported in FCP looked slightly different from what I was doing in Color, then the final export in prores had more contrast.

 

[nyvz]

I always had issues when doing color correction in fcp. Rendered files processed in Color and imported in FCP looked slightly different from what I was doing in Color, then the final export in prores had more contrast.

Yes and I and others have noticed, especially with h.264 footage, that gamma looks quite different between QT, finder preview, and FCP. I don't have as much experience using prores or AIC with these different applications, so I can't say much about whether that is related to what you are seeing with prores.

Hi Guys, Does someone have a definitive reasons why to use Apple Prores over Apple Intermediate codec for GH1 / 5D footage ingested into FCP?

I've done several heavy grading tests and can't find any difference except Prores is twice the file size...? Does anyone have any side by side comparisons?

As to AIC vs Prores, my understanding is that AIC was specifically designed as an intermediate codec for HDV-aquired material. As such, it uses 1440x1080 non-square pixels and 8-bit 4:2:0 sampling. My main concern in using AIC for GH1/5D or any other 1920x1080 native recording would be downscaling to 1440x1080. Otherwise the 10-bit 4:2:2 sampling you get from ProRes is likely just an extra bits without any additional information in it.

If you are really concerned about file sizes, I'd recommend thinking about ProRes LT, which will give you similar file sizes to AIC without throwing away pixel resolution (but with twice as much compression since it is giving you 10bit 4:2:2 1920x1080, which is actually 2.2x as much information to compress as 8bit 4:2:0 1440x1080 ). I'd always trust additional compression over throwing away pixels, as throwing away pixel data is generally the least efficient (from a quality/size standpoint) form of compression.

It seems a little tough to compare, and it really is up to you to decide what works best for you and whether you are more comfortable throwing away pixel data or adding more compression. It's also tough to know how AIC and ProRes DCT compression implementations compare, since it seems like ProRes might be a newer generation. Compression-wise, however, AIC seems to have a 5:1 compression ratio, whereas ProRes HQ is 6:1.

Anyway, there is no right answer, as it may be up to you and your workflow and your storage requirements. I have always preferred to do no transcoding at all whenever possible. These days I only use PPro CS5 since it allows really smooth native editing of pretty much anything I have thrown at it (h.264,mpeg2,r3d,etc) even in the same timeline plus realtime GPU effects and none of the playback and gamma issues I used to have with FCP. Re-compressing footage, no matter how good your intermediate codec will reduce the quality of your footage, take a lot of time and energy, and waste a lot of hard drive space.

 

[Ben_B]

Quality of ProRes is much better...I've done tests with both and when you watch in full resolution you can see the difference. With higher bitrate footage you can even see the difference between LT and ProRes...but I don't think we'd need HQ for these cameras.

 

[nyvz]

Quality of ProRes is much better...I've done tests with both and when you watch in full resolution you can see the difference. With higher bitrate footage you can even see the difference between LT and ProRes...but I don't think we'd need HQ for these cameras.

Can you elaborate? Is your observation related to holding detail/resolution, avoiding artifacting, or what? I would definitely expect ProRes to maintain detail better as it does not scale the horizontal down to 1440 as AIC does, but it seems that even ProRes HQ applies more compression than AIC, so if it is able to do so with less artifacting (blocking, mosquito noise, softening in certain luminance ranges, etc) that would be an interesting finding.

 

[diegocervo]

Yes and I and others have noticed, especially with h.264 footage, that gamma looks quite different between QT, finder preview, and FCP. I don't have as much experience using prores or AIC with these different applications, so I can't say much about whether that is related to what you are seeing with prores.

Yes, but I've been testing the production premium suite from adobe this month and I had no problems at all with gamma, contrast, etc from timeline to color correction in AE to final export. I've been always using prores files so I guess these issues have nothing to do with the way this codec works but with the editing software. Have you tried it out?

 

[Ben_B]

Isn't the fact that it's not throwing away pixels worth it in and of itself? I am sure there are other quality differences but I can speak mainly from gut instinct based on personal experience with footage from both, but I don't have specific test clips to show (I could make some though.) There is a saying in IT: storage is cheap.

 

[nyvz]

Yes, but I've been testing the production premium suite from adobe this month and I had no problems at all with gamma, contrast, etc from timeline to color correction in AE to final export. I've been always using prores files so I guess these issues have nothing to do with the way this codec works but with the editing software. Have you tried it out?

Well it depends what you mean by the codec since it usually refers to a decoder and encoder combination, but yes, the issues you are seeing seem to not be related to the encoder in the camera but rather the decoder that is used by NLE/player software.

I would agree that I generally trust CS5 a lot more than FCP to handle footage properly without any shifts. Most of my experience is with shooting 7D h.264 footage, and when I edit it in CS5 it looks just like I want, but anything I hand off to editors using a FCP and Prores transcoding workflow usually ends up looking wrong.

That said, in the past I have edited a few things from 5D/7D in FCP without Prores transcoding and never had as much issue with shifts. It could just be a matter of a difference between quicktime and prokit versions, which is still a pain to test and deal with.

 

[nyvz]

Isn't the fact that it's not throwing away pixels worth it in and of itself? I am sure there are other quality differences but I can speak mainly from gut instinct based on personal experience with footage from both, but I don't have specific test clips to show (I could make some though.) There is a saying in IT: storage is cheap.

Yeah, I agree, between AIC and ProRes, ProRes is a clear winner in my mind, but from my standpoint neither is a particularly good option if you can edit natively. I use neither, so I would tend to approach the comparison a bit more academically. But yes, throwing away pixels really shouldn't come into the equation unless you are desperate.

 

[Cosimo Bullo]

One vote for PreResHQ over standard PR on the 5d if you're messing around in shadows a lot. We've seen much improvement with HQ then.

Also, we've been cutting while traveling quite a bit and so have been doing PR Proxy for the portable temp drives, then PR HQ for the final cut and grading. Fairly easy to make the switch in FCP.