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AC3 Audio when extracting from DVD, Newbie Question
Sniffer
post Aug 4 2003, 15:37
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I have one doubt,

When i extract (i use graphEdit) the audio from the Vob's Files (The audio is on ac3), i extract it to wave, it gives me at least 1GB of audio, then i take this wave file and encode to MP3/OGG, and i use the preset standard or Q6 for OGG.

My questions??

1 - I have heard that if i extract the audio to ac3, it will give me 192kb, is this true???So there isn't no point to what i'm doing VOB - AC3 - WAV - MP3 Or OGG.

Ex: VOB - AC3

2 - If i do what i'm doing

EX: VOB - AC3 - WAV - MP3 Or OGG i will get less sound Quality because i'm transcoding at least two times??? Is this correct.

3 - So the best to movies is AC3 (I suppose), there is any tools to work with AC3 Files (Please recommend, i know there is a lot, but i want the best to QUALITY).

MiniDisc Relationed

1 - I have MiniDisc, and i record in real time by an Optical USB device connected to my portable MiniDisc and PC. I do like this.

CD - WAV - MP3 or OGG - MiniDisc (Realtime)

From MP3 to MiniDisc i'm transcoding again???? so getting less QUALITY.

IF i'm there is any other way to turn around this situation???


Thanks for your time

Sniffer. smile.gif
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anthrax
post Aug 5 2003, 09:06
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First of all, I see little point in using GraphEdit to extract the audio from a VOB file. There are very good tools that were designed to do this for you. My suggestion is to pick up a copy of the latest BeSweet beta and GUI here. BeSweet can do downmixing, normalization, resampling, DRC, and not to mention direct transcoding to other formats that you won't be able to do from GraphEdit.
QUOTE
1 - I have heard that if i extract the audio to ac3, it will give me 192kb, is this true???
Not always. Not all AC3 audio on DVDs is encoded at 192kbps. On most of my DVDs, the bitrate for AC3 tends to be around 256-384kbps.
QUOTE
So there isn't no point to what i'm doing VOB - AC3 - WAV - MP3 Or OGG.
At low AC3 bitrates like 192Kbps, no. You're only going to lose quality be transcoding to another lossy format at the same bitrate, and there will be few (if any) benefits. You might as well mux the AC3 audio directly with the video. But if the audio was encoded at, say, 448Kbps, you may want to consider transcoding to lower-bitrate Vorbis or MP3.

QUOTE
2 - VOB - AC3 - WAV - MP3 Or OGG i will get less sound Quality because i'm transcoding at least two times??? Is this correct.
No. Your only transcoding one time. In the first step, all your doing is extracting the AC3 audio from the VOB file. You're not doing any sort of encoding. You are transcoding when you convert the decoded AC3 file to MP3/Vorbis.

QUOTE
3 - So the best to movies is AC3 (I suppose)
I don't quite understand you here. Please clarify: do you mean "best" in terms of size? Quality? Are you talking about DVD or PC movies?
QUOTE
There is any tools to work with AC3 Files (Please recommend, i know there is a lot, but i want the best to QUALITY).
For decoding AC3, any tool that uses Azid or liba52 for decoding should provide good quality decodes. I use BeSweet, IMO the best tool for the job, because of it's wide range of features (the most important ones to me are stated above). You may also like to check out HeadAC3he (available at doom9.org).

QUOTE
4 -From MP3 to MiniDisc i'm transcoding again???? so getting less QUALITY.
Yes. You are transcoding from MP3 to ATRAC (MD's lossy audio codec). Transcoding from any lossy codec to another will always result in a loss of quality.
QUOTE
IF i'm there is any other way to turn around this situation???

You can:
- rip to --alt-preset insane and then transcode to MD, minimizing quality loss.
- rip to a higher quality lossy codec (MPC, AAC, Vorbis) at high bitrates, then transcode
- rip to lossless (FLAC, APE) and then transcode to MD, resulting in no quality loss at all (suggested).

QUOTE
Thanks for your time

You're welcome. smile.gif


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Sniffer
post Aug 5 2003, 09:56
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Thanks Anthrax for your reply.


QUOTE
3 - So the best to movies is AC3 (I suppose)

I don't quite understand you here. Please clarify: do you mean "best" in terms of size? Quality? Are you talking about DVD or PC movies?



Yes, i mean in terms of quality, regarding that for movies we only have AAC,AC3,MP3,OGG,WAV....Althought i have heard that AAC gives better quality then AC3????

One personal Question?

1 - I will encode some movies, i would choose AC3, but the audio file from one of my movies for instance is 335MB, just to much to handle, I will burn 800mb cd's with method 2 (Without error protection) so it give's me more 95MB, in total i will have 895MB, i will use OGM (Because of the new features over Avi) and Xvid......What should i use for the audio AAC,OGG Or Mp3, take in consideration i don't want any crap sound (64kb or lower), i want to give to the audio MAX of 150MB.

2 - When i extract the AC3 from the Vob's,it happens something strange, I play it with BSPlayer, no problem but i have to put the volume to the MAximum to hear well, do you Know what happen..............the file is with Low volume.


Thanks again, the answers to this questions will solve some doubts i have. Thanks. wink.gif
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anthrax
post Aug 5 2003, 10:50
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QUOTE
Yes, i mean in terms of quality
For bitrate ranges of 128kbps and up, I think the best codec for DVD rips would be either AAC or Ogg Vorbis (I prefer Vorbis). For bitrates below 96Kbps, I would recommend HE-AAC (aka AAC+), if you have Nero & the MP4 plugin, or if you don't, Vorbis or plain AAC once again.
QUOTE
Althought i have heard that AAC gives better quality then AC3????
Yes, IMHO AAC and other codecs such as Vorbis or MP3 perform better than AC3 at bitrates suitable for DVD rips (64kbps-192kbps, stereo).



QUOTE
1 - What should i use for the audio AAC,OGG Or Mp3, take in consideration i don't want any crap sound (64kb or lower), i want to give to the audio MAX of 150MB.
How long is the movie?

QUOTE
2 - When i extract the AC3 from the Vob's,it happens something strange, I play it with BSPlayer, no problem but i have to put the volume to the MAximum to hear well, do you Know what happen..............the file is with Low volume.
Use BeSweet to trans/decode the file and make sure HybridGain is selected in the GUI (or -ota( -hybridgain ) is specified on the CLI).


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marcan
post Aug 5 2003, 11:32
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ac3 192 is usually used for stereo mix on DVD. Higher ac3 bitrate is usually for 5.1. mix. For 5.1 you have also DTS which is better for me. Sometimes (often for music), you have LPCM (wav 48khz), this one is definitely best if you want to encode it later in a stereo lossy codec.

I use smartRipper. It can solve your size problem because you can demux directly the choosen soundtrack without the video.

I rarely transcode ac3.

Hope this help smile.gif
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