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Lossy Audio Compression => Ogg Vorbis => Ogg Vorbis - Tech => Topic started by: Instrumentallyinsane on 2017-12-16 22:55:35

Title: How to determine the Q of existing ogg file
Post by: Instrumentallyinsane on 2017-12-16 22:55:35
Is there an easy was to find the quality setting of an ogg file without saving a copy at different settings until a match is found?
Title: Re: How to determine the Q of existing ogg file
Post by: Nikaki on 2017-12-18 18:27:18
The ogginfo tool (from the vorbis-tools package) tells you this:


Nominal bitrate: 192.000000 kb/s
Upper bitrate not set
Lower bitrate not set
Vorbis stream 1:
        Average bitrate: 209.243033 kb/s

So you can infer from this that it's q6, because nominal bitrate is 192, and no upper or lower bitrate bounds were set.

Although I'm not 100% sure if this is completely reliable. It should be reliable if indeed a qN setting was used, but not sure what happens if exotic encoder options are used.

Note that ogginfo is a command-line tool. You have to run it from a console/terminal window (in Windows, that would be a cmd.exe command prompt window.)
Title: Re: How to determine the Q of existing ogg file
Post by: DVDdoug on 2017-12-19 19:49:32
I don't know about "quality" but bitrate is kilobits per second.   So, as long as you know there are 8-bits in a byte you can calculate the average bitrate from the file size and playing time.    (Embedded images can throw-off those calculations.  Other metadata & file headers are usually insignificant.)
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