Thursday, July 28, 2011

Scenasrist BD, x.264, qpfile chapter points


So I’ve been doing some experiments with x.264 encoding for Scenarist BD. I’ve been encoding with x.264 for a while, but pretty much for subtitling purpose since playback on raw BD while subbing is still too much to ask, even for my 1st gen i7 setup. And for professional production, I’ve been using Sonic CineVision 100%. Not that I’m super satisfied with the result, I can’t seem to find a better choice. But for anything under 10Mbps, the performance is really terrible.

So I decided to try x.264 by following this site. It’s pretty self explanatory. The only difficulty is putting the chapter marks on I frames. CineVision and Scenarist BD use very similar *.csv format for chapter marks, while x.264 requires qpfile which is somewhat different. The former ones use HH:MM:SS:FRAME#, and they have to be 24000/1.001 sped up ones (have to do 23.976->24 fps conversion, same goes for 30fps 30000/1.001), while qpfile uses total frame#. My NLE software is SONY Vegas, and I use frameserver as output, then create avs file, finally serve into megui. Unfortunately, this route doesn’t honor the chapter marks set in Vegas. So the qpfile is required. And if the chapter marks don’t match, you’ll get warnings in Scenarist BD (exact wording: PlayListMark is not an I-Picture). Although this is allowed in BD spec, you’d always want the chapter marks to be on I frame. In my experiment, the timecode in Vegas matches Scenarist BD format. SO here is what I’ve been doing:

Sample *.CSV file for CineVison is:


The timecode is copied from Vegas:


Same clip, just change the time format in Vegas, then copy it to a newly created qpfile (with notepad *.qpf):


0 K -1
4882 K -1
7075 K -1
10660 K -1
11062 K -1
14824 K -1
17700 K -1
21357 K -1
23359 K -1
25134 K –1

As for the timecode in Scenarist BD, you can use *.csv or *.tsv. The former is simpler, while the latter supports chapter name. The difference here between CineVision and Scenarist BD is that in Scenarist, you have to specify framerate and nondrop or drop frame.

Timecode Format    23.976    NonDrop   
Chapter Number    Timecode    Chapter Label    Mark Type
1    00:00:00:00       
2    00:03:23:10       
3    00:04:54:19       
4    00:07:24:04       
5    00:07:40:22       
6    00:10:17:16       
7    00:12:17:12       
8    00:14:49:21       
9    00:16:13:07       
10    00:17:27:06       
11    00:18:19:19       
12    00:20:31:05       

So for timecodes directly from Vegas, there’s no need to do frame conversion, but frames from DVD ifo or BD mpls files, it’s very likely that frame sped up is needed.

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