Converting PAL to NTSC for DIY worldwide DVD distribution

Posted by on Jan 18, 2015 in Articles

Continue

The problem of DIY DVD distribution worldwide is to create a product that can be played on any DVD player in the world. This means that it should be produced in NTSC format, since an NTSC-formatted DVD will play on any machine, whereas a PAL-formatted DVD might not work on NTSC players. At least, this seems to be the common knowledge.

When I was preparing for the shoot for the film Living the Tradition, shot in Ireland, I thought I would shoot at 30fps, so that I did not have to deal with frame rate conversions afterwards. But if I were to sell the film for European TV, which I hoped for and which I thought would be the most obvious market, then I would still have to convert to the PAL frame rate of 25fps. In the end, I decided to film at 25fps.

I edited the whole film at 25fps and then sat down to figure out how to convert the final film to produce a NTSC-formatted DVD for world wide distribution.

Below I describe my recipe. I need to give thanks to other people who have shared their experience and know-how both on-line and in the real world: Anthony Dias posted on the topic in Creative Cow and I used his Compressor presets, but significantly adapted his work flow to my own findings (see his original post in the thread here), Maarten in ‘t Hout from MVE Film helped me a lot, sharing his know-how of post production, compression and codecs, making excellent suggestions, as well as doing some testing with and for me. Finally Dan Brinkhuis from Science Media has kindly let me use his fast computer overnight(s) to do testing and compressions while I was doing other work on my own laptop.

The description below is for Final Cut Pro 7 and Compressor 3.5.3. It can be adapted for any combination of post production software. I take Living the Tradition as the example, which was shot on a Sony EX1 (XDCAM Codec) at 1080p25. I edited the film in this codec:

00 LtT Timeline setting

 

Step 1: Export XDCAM sequence from FCP7 to ProRes422HQ without Motion titles (intermediate file PR422HQ 1080p25, no titles)

This is a straight forward export using FCP7’s Export function and selecting Apple ProRes 422 (HQ) as the export codec. In all the steps to follow sound is just exported and passed through. As the film was 92 minutes long, I had to work my way through in chapters and at the end do an extra step to get the sound in place (Step 7).

One of the problems I ran into in Step 2 of this process was that when I had a Motion file with some text and/or graphics over images with a lot of movement (pans, tilts, driving cars, etc.), the graphics would go blurry. For example, this title over an image taken from a driving car with the background changing fast looks OK when at the original frame rate,

Detail of title on fast changing background (1080p25)

but looks like this when I changed the frame rate (as in Step 2):

Detail of title on fast changing background after frame rate conversion (1080p23.98)

To solve this problem, I switched off the titles in the cases of moving backgrounds, and added them back in again during Step 3.

 

Step 2: Use Compressor to go from 25fps to 23.98fps (intermediate file PR422HQ 1080p23.98, no titles)

NTSC-readable DVDs can be both at 30fps or 23.98fps. I figured that instead of going from 25fps to 30fps, where the transcoding algorithm would have to invent 5 new frames for each second of film, I’d better transcode to 23.98fps, where the algorithm “only has to lose” 1.02 frames each second. When I transcoded using Compressor by simply changing the frame rate of the target file to 23.98fps, all slow pans and tilts in the film that were smooth at 25fps, became un-smooth. With the help from Maarten in ‘t Hout I found that adding motion compensation solved the problem. Compressor allows for different levels of motion compensation under the Frame Controls in the Inspector, going from “Fast” to “Best”. However, the better the compensation, the longer it takes to transcode. I found that a good compromise between transcoding time and end result was the “Better” selection.

Here are two example excerpts comparing 1080p25, 1080p23.98 with and without motion compensation (even though of course Youtube re-transcoded all these files…):

Here is the Compressor 3.5.3 preset to be installed in ~/Library/Application Support/Compressor/, or to create yourself using

02 Compressor setting 1

02 Compressor setting 2

 

Step 3: Add titles back in FCP7 and export again to PR422HQ (intermediate file PR422HQ 1080p23.98, with all titles)

The next step is to put back the titles taken out in Step 1. Import the file created in Step 2 into FCP7 and put it on a new sequence. If the codec of this sequence is not the same as the codec of the file, then FCP7 asks if you want to set the codec of the sequence to match the codec of the clip. Say yes.

03 change sequence settings

The sequence setting should now read

03 Sequence Setting

Edit the titles back in and export a new file in the same format.

 

Step 4: Use FCP7 to downscale to NTSC frame size (intermediate file PR422HQ 720x480p23.98, with all titles)

Maarten in ‘t Hout suggested to use FCP7 to downscale from full HD, at 1920×1080, to NTSC DVD, at 720×480. It seems that FCP7 has a very good re-scaling algorithm. Create a sequence with the following settings (crucial is to check “Anamorphic 16:9”)

Sequence settings for rescaling from 1920x180 to 720x480

and edit the file created in Step 4 onto this sequence, answering “No” to the question if you want to match the sequence settings to the clip’s format.

 

Step 5: Join it all together in FCP7 (intermediate file PR422HQ 720x480p23.98, with all titles, full film)

Living the Tradition is a 92 minute film. In order to manage the time spent in all the previous steps (especially Step 2 is time consuming), and since I needed my computer for other tasks too, I did the Steps 1-4 per chapter of the film. I created a new sequence with the same settings as in Step 4, added all the chapters as created by Step 4, and exported the complete film in this format.

 

Step 6: Use Compressor to create a MPEG-2 ready for use in DVD Studio Pro (final file MPEG-2 720×480 at 23.98fps)

I used the Anthony Dias’ Compressor settings to convert the ProRes422HQ 480p23.98 version of the final file from Step 5 to MPEG-2 format, ready to use in DVD Studio Pro (download the Compressor preset here)!

SD DVD settings from Antonio Dias

 

Step 7: Convert the sound of the whole film

All these previous steps where done without considering the sound, because I split up the process in chapters. To transform the sound from the 25fps version to the 23.98fps version I found the following workflow to be the most reliable: (1) export only the sound from the original full edit to an AIFF file, (2) in FCP7 create a sequence with the following settings

07 jpg film

and edit the audio file created in the first step onto this sequence, (3) export this sequence with these settings, creating a video file with a black image at Photo-JPEG 81p25, (4) used Compressor with the settings below to create a black video file PR422HQ 81p23.98, no motion compensation needed of course!

07 compressor settings 1

07 compressor settings 2

(download this Compressor preset here), (5) import the resulting video file (black image with sound only) into FCP7 and extract just the sound from this clip or use QuickTime Pro to open the file and export just the sound, (6) put this sound file (now of the same length as the film at 23.98fps) into Compressor and use Anthony Dias’¬† audio preset to export to AC3 format, ready to use in DVD Studio Pro.

 

Even though it involves quite some steps and takes up quite some time, this series of steps has worked well for Living the Tradition; the DVD has sold world wide and to date I have not received any complaints about it not playing. I reckon that perhaps some steps could be skipped (for example resizing could be done at the same time as adding the Motion titles back in), but I preferred to do it very systematically, changing only one parameter at the time as it were, so as to keep the most control over the process and its possible flaws.