Re: Convert mp3 enbulk
On Mon, Feb 20, 2012 at 11:50:30AM -0700, Bob Proulx wrote:
> Curt wrote:
> > Bob Proulx wrote:
> > >> I'm lazy so I'd use the command line.
> > > I have the opposite problem. Everything I have is in ogg format. But
> > > sometimes I want to play on a device that doesn't understand ogg and
> > > can only play mp3 format. I simply convert the file to .wav format
> > > and then encode it again to mp3. You could do something similar.
> >
> > That's seems silly. Why convert it to wav first? Why not convert
> > directly to mp3:
> > ffmpeg -i example.ogg to example.mp3
> > or whatever the command would be.
>
> In my case I needed to produce mp3 files and mp3 encoders are of
> course patented and so not available in every tool and not available
> in the free ffmpeg. Since wav files are lossless they are the desired
> middle layer. If you are dealing with an audio collection then the
> size of the intermediate wav file isn't going to be a limiter. The
> cpu encoding will be the limiter. So for me going ogg to wav and then
> wav to mp3 was just perfect and impossible to do with ffmpeg.
>
If you instead use flac as an intermediate step, you may be able to
preserve the meta tags. Going to wav, you will almost certainly lose
them.
> Plus because ffmpeg is not the best tool for the wav to ogg task. It
> is great for producing wav files but not as good as oggenc for vorbis
> encoding.
>
> $ ls -log 01_-_An_Awful_Lot_Of_Running.mp3
> -rw-r--r-- 1 5.9M 2012-02-20 11:03 01_-_An_Awful_Lot_Of_Running.mp3
>
> $ ffmpeg -i 01_-_An_Awful_Lot_Of_Running.mp3 01_-_An_Awful_Lot_Of_Running.ogg
>
> $ ls -log 01_-_An_Awful_Lot_Of_Running.ogg
> -rw-rw-r-- 1 27M 2012-02-20 11:06 01_-_An_Awful_Lot_Of_Running.ogg
>
> $ ffmpeg -i 01_-_An_Awful_Lot_Of_Running.mp3 01_-_An_Awful_Lot_Of_Running.wav
> $ oggenc 01_-_An_Awful_Lot_Of_Running.wav
> $ ls -log 01_-_An_Awful_Lot_Of_Running.ogg
> -rw-rw-r-- 1 3.3M 2012-02-20 11:04 01_-_An_Awful_Lot_Of_Running.ogg
>
> Look at the sizes of the files. This is because ffmpeg is producing
> flac not vorbis encoding. Remember that ogg is a container format not
> an encoding format. In that case you might as well simply keep the
> wav files. But of course we compress as a compromise in order to save
> disk space. A *lot* of disk space.
>
> There is almost certainly an option to ffmpeg to encode with vorbis
> encoding. There is an option for everything. And it is changing.
> Between Lenny and Squeeze and Wheezy it is evolving. I know that by
> the time I read through all of the documentation to figure it out that
> I would already have had the job done using oggenc. (This is
> someone's chance to jump in and tell us the optimal set of options to
> ffmpeg to produce an ogg vorbis file. I know I would note the options
> down for future reference.) But using oggenc is simple, immediately
> obvious, and does a good job of it.
>
It would have to be one of these (but I haven't tested it)
ffmpeg -i somesong.mp3 -acodec vorbis somesong.ogg
or
ffmpeg -i somesong.mp3 -acodec libvorbis somesong.ogg
> Remember that the Unix philosophy is all about modularity. Write
> small dedicated tools and join them together to produce a greater
> whole. I would like to simply pipe from simple program to simple
> program and let a multi-core cpu run the processes in parallel. Tools
> that try to do everything in one program with ten thousand options
> violate that philosophy and are harder to use and harder to expand
> upon.
>
> > Anyway, it's double lossy whatever you do, and maybe even worse if you
> > go the roundabout wav route (though I don't really know, but you can't
> > fool mother nature).
>
> Decoding and encoding again will obviously introduce artifacts. Just
> like the laws of thermodynamics say you can't win, you can't get
> ahead, you will always lose. But if you only have one thing and you
> want to get to another thing then you are going to transcode because
> that is what you have and there is no other way. And if you are an
> average individual with average ears and an average set of headphones
> listening in an average environment it is unlikely that you will be
> able to tell the difference. It won't be of the highest audio quality
> but neither will it be of the lowest. And if your purpose is to
> listen while say biking out in the wind then you are most definitely
> not going to be able to tell the difference.
>
I decided a few years ago that I'd use flac for my entire music
collection, and if needed, convert to another format for reasons of
portability, etc. This way I only get one lossy transcode.
> > Or maybe my understanding is shaky you'll illuminate me.
>
> Bob
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