DVD Video

In the past day and maybe even a little last week I’ve been spending time reading up on and trying out different techniques for video authoring and converting. It’s a pretty vast subject and there are plenty of tools both open source (or freeware) and commercial products to help. One thing I’ve found to be a real pain is trying to watch some Chinese movies that we bought on our Sony DVD player. It’s a no can do.

American video equipment (DVD players and TVs) all play NTSC format video, but very few can handle PAL format video. Well, sure enough the movies we have are PAL format. Instead of the 720×480 at 29.97fps that NTSC expects, the DVDs are 352×288 25fps. They’re a low quality, long running DVD in the wrong format. You can buy DVD players with PAL to NTSC converter chips in them, but they start at $200 each and go up very quickly from there. A $75 LG DVD player with a chip will set you back $299. No thanks.

So, I’m doing what I can to learn how to convert PAL to NTSC format on my computer using free tools. It’s a challenge. The last test I ran resulted in a great looking video, but the audio did not properly sync up. Essentially the conversion includes demuxing the DVD content using dgindex (extracts the audio and video files out of the vob files). Then use another set of tools to resize the video to the NTSC resolution and increase the framerate from 25 to 29.97. Changing the framerate is a process better left to mathematicians, but there is a nice tool that helps (dgpulldown).

In the end you need to sync up and combine (mux or encode) the audio and video streams into one vob (or some intermediary type that a DVD authoring package can handle) and finally burn to a DVD. The process can be painful especially to the newbie who just wants to get it done. The last test I ran took 6 hours to resize the video and encode it into an mpg. Only then did I find out that I can only change the framerate before encoding, but my tests show that doing that results in out of sync video and audio.

I’m cutting my losses for now and reverting back to using Nerovision express. It does an okay job of converting PAL to NTSC, but sometimes it creates some visual defects that are annoying. Again it is not a quick process. Nero takes about 3 hours to convert and encode the files before I can burn them. I also need to recreate the chapters and menus, which is a hassle seeing as the episodes are not of equal length. You have to watch parts of the video to find the end and then mark the chapter.

I’m sure there is a much easier way to do all of this, but I’m not ready to lay out big bucks on software to do it. It isn’t cost effective and I’m sure that it can be done I just don’t know enough about what I’m doing and working with to make much progress.

I will say one thing though that the avisynth tool is pretty impressive. You create an .avs file containing some basic avisynth script commands and then use the avs file using other software. Avisynth acts as a frameserver, which uses the script commands to process the specified input and then serve it up frame by frame to the player. You could use this to read in an AVI then apply some filter or resize the file and then output it to a player on the fly. Pretty neat stuff.

If I ever figure out the best way to create a high quality conversion from PAL to NTSC I will have to post the steps. Until then it’s back to the research for me.