I'm looking at the dvd-ntsc.cfg and dvd-pal.cfg files. They define DVD
profiles that are based on ffmpeg as an MPEG2 encoder.
Now, ffmpeg is very fast and complex, but with regard to MPEG2 it has a
problem: the bit rate control is pretty weak.
http://lists.mplayerhq.hu/pipermail/ffmpeg-user/2008-January/013457.html
As a result, the DVDs generated might be a bit non-compliant and may
have issues playing on some standalone players. At best, an aggressive
limit has to be imposed to the max bitrate, in order to not exceed the
max specified by the standard, resulting in low image quality (which
appears to be the case with the dvd profiles in transcode).
The alternative that I've been using for many years is mpeg2enc. It's
slower than ffmpeg, and it's a dedicated tool - it only encodes MPEG2
and that's all. But it has much better rate control, and the image
quality appears to be better.
These are the scripts that I use with mjpegtools-1.9.0rc2 and
transcode-1.1.0-alpha6 to convert DV files to DVD - the scripts are
fine-tuned for maximum image quality (hence the encoding is pretty slow,
since all the quality options are turned way up):
http://florin.myip.org/soft/conv-dvd/
To generate almost any other kind of content, I use ffmpeg and mencoder,
but for DVD-compatible MPEG2 I've found that mpeg2enc is still a better
choice.
Would it be acceptable to create alternative DVD profiles that use
mpeg2enc instead of ffmpeg? This type of encoding would be slower, but
the image quality would be better and the DVDs more compatible with the
standalone players.
--
Florin Andrei
http://florin.myip.org/
