Converting AC3 streams into stereo .ogg vorbis files

[jacktradesy2k]

Hiya,
I wanted to know if I am still uptodate with my way of converting AC3 -> stereo .ogg vorbis files.
It is mainly based on the gordianknot procedure for dvd back up's.
1. Transfer vob's to the hd.
2. Extract AC3 stream using 'DGIndex'
3. Convert AC3 files with headac3he-0.23a into ogg vorbis files.
4. Final editing with Audacity

I also wanted to ask a question about sound levels for when converting from AC3 -> stereo ogg vorbis or mp3

Now to my questions.
Is 'headac3he' still best/only way to convert AC3 -> stereo .ogg? or did i miss some newer/better/easier to use tool?
If not ok.
I due have some questions about some of options inside of 'headac3he-0.23a'

1. What is the best/recommendable sample rate for portable players?
48kHz or 44.1Khz? I am bit overwhelmed there...

2. Is the option 'Booster' the right one to enhance the sound for portable players?
Since I encounter the sound level difference quite often when converting from dvd to ogg or mp3.

I quite often have to raise the volume levels on my personal player from about 22->35
Which is pain if the following track is properly balanced.
As side note I did try normalizing and variable bitrates on my older mp3 files and didn't like the results.
Which is why I started looking towards ogg vorbis.

Thx, Jacktradesy2k

[Inspector.Gadget]

Try using MeGUI, which works as a wrapper for either Avisynth audio or Directshow audio input, and uses more recent/optimized builds of OggEnc.

[turok]

convert the ac3 stream to a lossless before reencoding to another lossy format. ac3 is a lossy codec . ac3 and vorbis have different ideas to which data to get rid of. u lose a bit of quality reencoding from a lossy source. convert to lossless then reencode to lossy for best quality retainage.

also keep the sample rate original why do u want to change it?

[john33]

convert the ac3 stream to a lossless before reencoding to another lossy format. ac3 is a lossy codec . ac3 and vorbis have different ideas to which data to get rid of. u lose a bit of quality reencoding from a lossy source. convert to lossless then reencode to lossy for best quality retainage.

also keep the sample rate original why do u want to change it?
It makes no difference whether you create intermediate wave files in the conversion. The 'loss' is in the encoding, not the decoding.

[nurbs]

If your portable supports 48 kHz, most do AFAIK, there is no reason to resample. Unless your source has a very high sample rate like 96 or 192 kHz or you hardware demands it you should avoid resampling.
Don't know what booster does, but if it is DRC it should be avoided. Gain/normalization is OK, in fact it's probably a good idea to normalize after downmixing from 5.1 to stereo unless the downmix is normalized to begin with.
About normalizing old MP3s: It does more harm than good, no matter if you encode to MP3 again or Vorbis. The quality is only going to be worse since both are lossy codecs. You should look into adding ReplayGain information to those files. It's a tag, so it's non destructive, but your player has to support it. Works with both MP3 and Vorbis IIRC.
BTW john33 is completely right.

[john33]

If you're applying replaygain to mp3s, use mp3gain. It directly alters the gain value within the mp3 data and can be reversed, it is a lossless process. The downside is that it can only be altered in 1.5dB increments. The plus side is that since the gain value itself is altered, no special player requirements apply. Use vorbisgain for ogg vorbis files. That does create a tag that needs to able to be read by the player in order to be applied. If the player fails to read it, it should just be ignored, but any self-respecting ogg vorbis player should be able to read and process the information.

[Blue_MiSfit]

Hello!

I'd suggest taking a look at eac3to as well. It doesn't do Vorbis encoding AFAIK, but it does have a very accurate ac3 decoding process, including things like downmixing, delay correction, and properly bypassing DRC on decode.

If it was me, I'd use eac3to to generate an intermediate WAV, and feed that into OggEnc. Of course, if it was me I'd probably be using AAC - but that's neither here nor there :D

Derek

[jacktradesy2k]

Hiya,
Couple of points from myside.
About convertering into wave format sounds to me bit of extra round around block.
Looking at it from the gordianknot guide point of view it than on the other hand
it make total sense though.
I also have to admit that I don't know enough about the AC3 format - if it has navtive compression or not.

At this point I should squeeze in a little story of the ffmpeg filters for Audacity and how I went WOW!
Since than open them video files directly with Audacity and after some editing export them stairght away into ogg vorbis NICE!
Now that's some less extra tours round the block.
About the entire buisness about converting old mp3's into ogg vorbis (or AC3 into other formats).
Since compression is means removing unnecessary parts - which might be of importance in some other instance...
I am therefore trying to avoide the entire story overall (mp3 -> ogg vorbis)if possible.
If the original source is still avialable I just re do the entire edit from start with them latested tools.
Also I do have to suspiscion that large wave files - when left for a long time period on the HD (several mounths) tend to get corrputed
via the file system due to defragmentation.

Thx for all the new tools - I had go with MeGUI on my atom processor quite interesting results.
And also one on my 5yr old main notebook. fan=chainsaw noise!

I am still seeking some more answers on the volume issue which is a major pain when converting dialogs out of movies.
First I can barely hear them on the train and than the next track blasts into my ear.
Is their some rule of thumb which might help figuring out by how many dB 's I should raise the sound?
Or how to read in Audacity some 'scales'? which might help?
Also someone asked me if my personal player supports special feature
I guess It's the easiest way to just post the name of my player
It is a COWON D2 - I will add link to the spec sheet once I found one.
Thx, Jacktradesy2k
for all them hints (guess I caused mini avalanche here!LOL)