Hello people.
I'm curious about something and i would like your opion on it. Lets say i have one .mp3 file at 320 kbps and i decode it with E.A.C. to .wav and i encode it back to .ogg 320 kbps. Will that ogg file lose from its audio quality compare to the original .mp3 file that i have?
What if i directly convert it from 320 kbps (.mp3) to 320 kbps (.ogg)?
Which of those methods you think is more accurate in tems of quality? and another thing if i rip the same file from the same CD 1rst at 320 kbps .mp3 and second at 160 kbps .ogg (with aoTuV b5 encoder) which of those 2 you think will have the best audio sound? And if the .mp3 320 kbps sounds better than the .ogg 160 kbps (with aoTuV b5 encoder) then with what bitrate the .ogg 160 kbps (with aoTuV b5 encoder) equals to in terms of .mp3 format?

I would like your opinions on those questions

Converting directly from MP3 to OGG is exactly the same as decoding to WAV then encoding the WAV to OGG, just a little more streamlined.

Welcome.

Yes. Transcoding from lossy to lossy will always result in a loss of quality. Whether you can hear that loss is another question, which only you can answer.

As already said: the processes are actually the same; there is no way to go from MP3 to Vorbis directly.

One would presume that the 320kbps MP3 would have better quality, but it partially comes down to how you hear the files. As to the MP3 equivalent of a 160kbps Vorbis file: you may find that a 160kbps MP3 is indistinguishable. If not, I suspect you would have to raise the bitrate a little, rather than lower it. You really need to investigate blind listening tests (ABX) and do some testing yourself.

Don't think too much about sheer numbers. As Synthetic Soul already said, personal listening tests are the actual way to go, since it's the music you listen to, not the bits. For this reason, the question whether 320 kbit/s MP3 or 160 kbit/s Vorbis was better could be nullified by the fact that most certainly both encodings sounded transparent to you. And how should one distinguish two transparent pieces of music from each other?

The case would be another if you chose quality levels which are known to be some kind of transparency thresholds. For Vorbis there's a topic about many people going for -q2 (~100 kbit/s) to achieve indistinguishable results, while in an MP3 poll -V5 (~135 kbit/s) was often chosen by the users.

Edit: The threshold values were chosen by an audience of average users visiting these forums. Of course, they don't have to apply to audiophiles who trained their hearing for finding subtle encoding artifacts in lossy files. Casual listeners, as well as those people who prefer enjoying the listening to their music instead of constantly searching for flaws, usually don't perceive these artifacts.

Thanks guys for your advices.
Are you all using .ogg vorbis? and whats the quality you have chosen to rip your CDs? I personally use q5 which equals to 160 kbps and i think is high enough to give me a satisfy quality audio sound.

I starting off using q5 about a couple of years ago, for use on my home PC and iriver portable player. More recently I started using q4.5 when I started running out of space.I'm happy with q4.5, it sounds great to me. Ogg Vorbis has improved a fair bit since I started using it, especially thanks to Aoyumi.

Mr Bungle has a good post there, I too started off at q5 but then dropped to 4.4 as that is about 140kbps (I like the number 4 lol) and music to me sounds excellent, the best encoder to use is Aoyumi's release

http://www.geocities.jp/aoyoume/aotuv/

Furthermore, I use the SSE-optimized Lancer builds of the currently officially recommended aoTuV Beta 5 encoder. By using SSE(1/2/3) instruction sets and multi-threading they provide significant speed improvements.