I'd like a conversion option that focuses on the quality of output rather than conversion speed or file size. This is not a matter of cranking up the bit rate because that creates files that are overly large for the intended goal, maintaining quality. I think this would be useful for home entertainment applications where a format change is necessary and the user is sensitive to compression errors.
For example, I usually use VOB Passthrough to keep the original quality of the movie. However, there is no container format for the PS3 that supports MPEG2 + AC3 + Subtitles. This presents a problem on foreign language movies that require subtitles. I can convert these at the maximum bitrate but this creates a very large file and still introduces some compression errors.
I have not come to this feature request empty handed. Now that I have a new PC with a high-end processor, I have created a rudimentary script that will convert the VOB file to an XVID AVI. I offer it here so that the DVDFab developers understand what I am talking about and might be able create the option more easily:
mencoder IN_MOVIE.VOB -alang en -channels 6 -slang en -oac copy -vf filmdint -ovc xvid -ffourcc DIVX -ofps 24000/1001 -of lavf -xvidencopts fixed_quant=2:chroma_opt:vhq=4:autoaspect:max_bframes=0:quant_type=mpeg:threads=3 -o OUT_MOVIE.AVI
This basically uses a high quality motion search (vhq) and a fixed quantizier (fixed_quant) to vary the bitrate for each frame so that the same quality level is maintained. The other options on the command line where included for completeness:
- Select the 5.1 English AC3 as a passthrough
- Detelicine the video to 23.976fps (DVD film source)
- Encode the video as XVID
- Mark the video FOURCC as DIVX so that the PS3 will play the file correctly
The numbers I used are the maximum reasonable settings and create a file that is about 30% smaller than the VOB. After the conversion I take the resulting AVI and repackage it into a DIVX container with the subtitle files created during the VOB extract. If you try this at home be warned that my Quad 2.8ghz machine only processes at about 15-20fps (or about 3-4 hours for a 2 hour movie). The resulting file is almost perfect and I am able to turn on the subtitles as needed. If this was available on DVDFab, I might use burned in subtitles.
Thanks for your consideration.