Hiya.
Again, I would be very careful about going too close to the wire when encoding video files.
1. The discs are reported as different sizes when compared to computer HDD. Whilst it may say 4.7Gb on the packaging it is not that much in reality so be careful.
2. The closer you get to the outer edges of the disc, the riskier the burn becomes - the vegetable dye used can be thinner at the edges so I would never try to cram a written disc too full. A replica, yes but not written.
Personally I think DTS blows AC3 away in terms of the image and the quality. Here's why:
AC3 at 448Kbps is not full bandwidth/full range - that requires 640kbps which is out of spec for DVD-Video. You will get a situation where all the top end goes unidirectional above somewhere around 14-15kHz and that is where all the air & space is on a mix. Yuk.
Plus you also have to factor in downmixes to stereo as well as RF output and all that means is compromise, compromise compromise. Watch the metadata too - setting production information will attenuate the mix and setting Dialnorm will attenuate the L-R-Ls-Rs channels respective to the C channel, which in these cases is always assumed to be carrying just dialogue and this brings me to the core of my issue with AC3.....it was developed for film use, not music use and the metadata will work with compressors & limiters to ensure dialogue intelligibility (ie turn the other channels down given the DRC profile conditions). Sadly turning this all off does not help either, as a player where DRC has not been turned off (it is usually ON by default in DVD/Blu-ray players) when it gets to play a file that has no DRC flag set will assume it should be "film main" and bring the hammer down accordingly. The usual approach is to set to "Music Light" as this is the least intrusive - and if the DRC setting is OFF in the player this flag will have no effect.
DTS on the other hand uses a bitrate of 1536kbps (the same as 16-bit 48kHz PCM audio) and in usual use does not allow setting of dialnorm (if this must be set, set it to -31 or no attenuation) and it is full bandwidth. Yes it does use 3 times the space on the final disc, but even if you are running PCM stereo & DTS that still leaves a good 6Mbps for the video, and that should be plenty. Surround fans will thank you for it.
There is a downside - DTS is an optional codec, not a mandatory one so cannot be used as the sole stream. The end user must have either a DTS decoder in his/her player or their amplifier and I assure you all surround fans have this. If you have room, add an AC3 as an afterthought but nobody will play it.
