Creating high quality avi from DVD
loic.martin3 at gmail.com
Wed Jan 21 17:46:03 UTC 2009
Ben Edwards wrote:
> Thanks a lot for taking the time and giving a very detailed/useful
> reply. I do have a question about the audio. I tend to copy the
> Dolby Digital audio rather than encode into .ogg etc. Am I correct in
> guessing .ogg would give me a stereo, rather than surround sound,
> track. I am verry keen to keep the surround sound. I guess this may
> be using a lot of bandwidth and may result in the quality of the video
> being not so good. I have actually gone to 1500 bits (with xvid) but
> am not totally happy with the quality. I will give x264 a go.
> Lastly do you know if there are any encoders that can use multiple cores?
By surround sound I'm assuming you mean 5.1 or 7.1 audio, since you can
have a surround effect with 2 channels (Dobly surround).
You can just keep the AC3 audio as is (DVD audio should be AC3), I
reencode to aac or ogg because I'm never planning to have anything else
than a good 2.0 setup, but if you've got a home theater thing I guess
keeping the audio as is would be just fine (especially if you still have
enough space for 1500kbps). However, you can also have X.X audio with
AAC, and it should be the same for OGG. just check the size your audio
takes, and then it's just a trade-off between audio and video quality.
1500kbps for the video is more than enough for x264, you can encode
almost any movie, even without going to advanced options (but don't keep
Avidemux default options, they are really low). With good encoding
choices you can get as far as 1000kbps (or lower) especially for anime
(max the ref + bframes), CG movies and low pace movies, so you'd do
great with 1500kbps.
x264 through either mencoder or Avidemux use multiple cores, either auto
or by using the threads options (2 time more thread than your number of
cores). By default they don't max the load, so you can nice/renice them
to high priority and/or launch two or three encodes at the same time.
There 's a very small decrease in quality when you increase the thread
count, so a purist would lauch multiple encodes with a few thread each,
but if I use that method it's more for maximizing the load.
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