Category Archives: Film

Film Finish Writing Me Plz

Working with 10bit 4:2:2 Quicktimes

So I finally got around to doing some compression tests. My source was a 1280×720 23.98fps 10bit 4:2:2 “uncompressed” quicktime. That is a typical file that comes across my desk. I wanted to see what compression I should set my Final Cut Pro timeline to. At first, I opened the quicktime in Quicktime Player and exported to a variety of codecs. But when I opened all of the files, I noticed that they were all darker than they should have been. That indicated to me that Quicktime Player had done some sort of colorspace conversion. So I redid the same test from inside Final Cut Pro. Sequence Settings were set to the same as the source video.

For the test, I used these codecs:

  • None
  • Animation (100%)
  • PNG
  • Apple Intermediate Codec
  • MJPEG-a
  • MJPEG-b
  • HDV
  • DVCPRO HD
  • Prores
  • Prores (hq)
  • 4:2:2 8-bit
  • 4:2:2 10-bit

Results

bar graph

So I noticed that None, Animation, PNG, Apple Intermediate Codec, and MJPEG went through a colorspace conversion. So I won’t be using them again.

HDV and DVCPRO HD were slightly fuzzier than the original, but also smaller than the remaining formats. DVCPRO HD also underwent a slight tonal change in image quality. DVCPRO HD also has poor cross-platform support, and both of these formats have restrictions on their frame size.

Prores lived up to its name, and was as fast to compress as the 4:2:2 “uncompressed” formats, while also yielding files over 75% smaller, with little perceptual quality loss. They also had the benefit of not causing FCP to re-render the timeline.

<needs more pics>

Conclusion

I’ll have to re-run this test with a simple filter applied to the image. I’ll probably add 8 pixels of black to the bottom or something. I think that 4:2:2 10-bit won the fps race because Final Cut Pro just copied the data instead of having to recompress as it did with all the other formats. I also haven’t figured out why Prores HQ was faster than Prores.

Film Nerd

My new DVD to Quicktime workflow

So I get asked to make reference samples off of DVD based material fairly often. Here’s my current quality emphasis workflow:

Rip relevant portion of DVD with DVD Decrypter

Create DGIndex project, decompress AC3 to PCM

Import DGIndex project to Avisynth

AudioDub() the decompressed PCM WAV into the Avisynth project.

Add any decomb/deinterlace/resize filters as normal.

Add the SwapUV() filter to the chain.

Save using VirtualDub using Direct Stream Copy

Install YV12 QuickTime codec

Export from Quicktime to whatever it is you do.

(OPTIONAL) If you need subtitles:

Rip .IDX/.SUB using VSRip from the decrypted IFO/VOBs

Find subtitle offset by selecting all previously deselected chapters previous to where you started in DVD Decryptor and write down the amount of time you skipped. Fine tune offset by DVD Decryptor stream processing outputs for the subtitles.

Tweak offset using VobSub Cutter

Tweak appearance using VobSub (I didn’t, I skip to…)

Edit the .IDX for the subtitles. You can enter the delay in here instead of using VobSub Cutter using HH:MM:SS:MS. Set align to:

# Force subtitle placement relative to (org.x, org.y)
align: OFF at LEFT TOP

Add the TextSub plugin to Avisynth

Programs Needed:

DVD Decrypter, VobSub, Avisynth, DGIndex, VSFilter (old version, not the latest, you’ll find out), VSRip, VobSub, YV12 Quicktime Codec, Notepad, Virtualdub, Media Player