Step 5 - Frameserving

Introduction

If we were to decode the movie to a raw AVI file before encoding it again, we would need more than 100 GB per hour (for PAL). Instead, to reduce the space requirements, we let a frameserver feed decoded frames to the encoder, one by one. A frameserver must be able to manipulate the input stream, since we have to resize the original DVD movie to SVCD format. If we want to add permanent subtitles to the stream, this must also be done by the frameserver.

There are two very good frameservers at the moment, namely VirtualDub and AVIsynth. VirtualDub has a nice GUI with real-time display of the effect all applied filters have to the input stream. AVIsynth is a script based solution without any GUI. Each has its advantages, but I've chosen AVIsynth due to its very fast resize filters.

How to

Install AVIsynth and MPEG2DEC.DLL. Now we just need to create a small script, before we are ready to encode. NTSC DVD's have a resolution of 720×480, while PAL DVD's are 720×576. For SVCD's it's 480×480 and 480×576, respectively. Thus, we must resize. If the movie is anamorphic widescreen we have to choose between keeping it that way, or letterbox it, which means adding black borders at the top and bottom. Please note that most standalone DVD players doesn't support the 16:9 flag on SVCD's, so when keeping the anamorphic format, you need either a widescreen TV or a 4:3 TV with a 16:9 feature.

Copy one of the example scripts below and modify it to your needs. You can find more info about the individual filters at the AVIsynth website. Important: You have to supply a (real) .wav file, even though we perform the audio encoding and multiplexing ourselves - if you don't, CCE will crash!

Adding subtitles

Install VobSub. You start it either by clicking the "VobSub Configure" icon (if provided) or simply by writing:

C:\> rundll32 vobsub,Configure
          

Now, in the main window select the subtitles to use and quit VobSub by clicking "OK".

Examples

These scripts demonstrate the usage of AVIsynth. AVIsynth scripts have the filename extension AVS.

#
# AVIsynth script for NTSC (no subtitles)
# by Jacob Laursen 
#
# Source: 720x480, 16:9 (anamorphic)
# Target: 480x480, 16:9 (anamorphic)
#
# (or source/destination: 4:3)
#

LoadPlugin("C:\WINNT\system32\mpeg2dec.dll")

video = mpeg2source("C:\DVD\movie.d2v")
audio = wavsource("C:\DVD\movie.wav")
clip  = audiodub(video,audio)

BilinearResize(clip,480,480)
        

#
# AVIsynth script for PAL (with subtitles)
# by Jacob Laursen 
#
# Source: 720x576, 16:9 (anamorphic)
# Target: 480x576, 16:9 (anamorphic)
#
# (or source/destination: 4:3)
#
LoadPlugin("C:\WINNT\system32\mpeg2dec.dll")
LoadPlugin("C:\WINNT\system32\vobsub.dll")

video = mpeg2source("C:\DVD\movie.d2v")
audio = wavsource("C:\DVD\movie.wav")
clip  = audiodub(video,audio)

subtitled = VobSub(clip,"vts_01_0")
BilinearResize(subtitled,480,576)
        

#
# AVIsynth script for NTSC (no subtitles)
# by Jacob Laursen 
#
# Source: 720x480, 16:9 (anamorphic)
# Target: 480x480,  4:3 (letterboxed)
#

LoadPlugin("C:\WINNT\system32\mpeg2dec.dll")

video = mpeg2source("C:\DVD\movie.d2v")
audio = wavsource("C:\DVD\movie.wav")
clip  = audiodub(video,audio)

resized = BilinearResize(clip,480,360)
AddBorders(resized,0,60,0,60)
        

#
# AVIsynth script for PAL (with subtitles)
# by Jacob Laursen 
#
# Source: 720x576, 16:9 (anamorphic)
# Target: 480x576,  4:3 (letterboxed)
#
LoadPlugin("C:\WINNT\system32\mpeg2dec.dll")
LoadPlugin("C:\WINNT\system32\vobsub.dll")

video = mpeg2source("C:\DVD\movie.d2v")
audio = wavsource("C:\DVD\movie.wav")
clip  = audiodub(video,audio)

subtitled = VobSub(clip,"vts_01_0")
resized   = BilinearResize(subtitled,480,432)
AddBorders(resized,0,72,0,72)