[linux-audio-user] How do you make an ogg?

[Frank Barknecht]

Hi,
Laura Conrad hat gesagt: // Laura Conrad wrote:

> A technical but mostly non-linux friend was asking me about where Ogg
> Vorbis is relative to MP3's, given the current status of MP3 encoding
> software.
> 
> I did a quick test of making an ogg from a wav, and my naive version
> produced:
> 
> [lconrad at tuba renfaire]$ ls -l hercules*
> -rw-rw-r--    1 lconrad  lconrad   4526080 Aug 18 14:14 hercules2.mp3
> -rw-rw-r--    1 lconrad  lconrad  12220015 Sep  3 12:30 hercules2.ogg
> -rw-rw-r--    1 lconrad  lconrad  49956104 Aug 18 14:09 hercules2.wav
> 
> I used ecasound to do the encoding, but what my ecasoundrc says it did
> is:
> 
> ext-ogg-output-cmd = oggenc --raw -o %f
> 
> oggenc is:
> 
> [lconrad at tuba renfaire]$ oggenc -v
> OggEnc v0.8 (libvorbis rc2)

oggenc 1.0 is out. You maybe should upgrade. 

> So my question is, is there a way to get the ogg file down closer to
> the size of the mp3 file?

You can encode ogg files in various ways: 

1) Quality 0-10 (--quality)

gives you a file with a variable bitrate. The actual filesize is a bit
difficult to predict, but if you experiment, this is the preferred way
of ogg-encoding.

2) min-max (--max-bitrate --min-bitrate)

here you specify borders for the bitrate. This way, your file will
never be bigger than max-bitrate * duration and never be smaller than
min-bitrate * duration
With these options you could get a very small oggfile :)

3) Bitrate (--bitrate)

This is a variable bitrate like 1) but should have a bitrate around
the value you have chosen. Although this is very much like you would
use a mp3-encoder like lame or gogo, it is not recommended by the
Ogg-Team: "This uses the bitrate management engine, and is not
recommended for most users." In my observations ogg-files encoded with
--bitrate do not keep this bitrate very well, they use bitrates much
lower. So the quality isn't as good as I expected from the bitrate
option. But YMMV. 

So, as with all lossy encoders, you will have to find a compromise
between filesize and audio quality. 

ciao
-- 
 Frank Barknecht                               _ ______footils.org__