[opus] Antw: Re: Beginner's questions/suggestions

[Ulrich Windl]

>>> Ralph Giles <giles at thaumas.net> schrieb am 21.12.2015 um 19:51 in Nachricht
<CAEW_RkshUM55uwdvU6DsE17pLZki651Xvvu7d2Y6jObePXZwCQ at mail.gmail.com>:
> On 21 December 2015 at 04:31, Ulrich Windl
> <Ulrich.Windl at rz.uni-regensburg.de> wrote:
> 
>> opusenc does not display the file name it processes. In Lunux when you use 
> some batch processing, it might be interesting! Example output for
>> "for f in *.wav;do opusenc --bitrate 160 $f ${f%.wav}.opus; done":
> 
> In situations like this, i usually insert an 'echo $f;' before he
> first command in the for loop.
> 
>> For the output, can't "Encoded:" and "Runtime:" be put into one line?
> 
> Probably, although it's hard to fit all three fields in 80 columns.

My idea was this: It seems opusenc outputs quite a lot of stuff that looks to be spread around lines rather arbitrary while missing the file names it's working on. My suggestion was to rearrange and consolidate the output.

> 
>> The next thing I'm sursprised it that VBR bitrate 160 is exceeded even for 
> the average most of the time:
> 
> The VBR encoding mode is designed to achieve comparable quality over a
> large variety of audio with the requested average bitrate, by varying
> that bitrate of each individual file depending on how difficult it is
> to encode.

I thought the algorithm were using a kind of budget: I temporarily overused, the next parts will be used using less bits. If the encoder bases the bitrate on the complexity of the input, why try to mess with the bitrate at all? Can't we say (like for JPEG) we want some quality (in percent), and the required bitrate is guessed (and output at the end), or specify some maximum bitrate, and the encoder outputs a guess of quality accieved for the given input.
I mean users should not have to know the very details of the encoding process to perform a typical use case.

> 
> The bias you're seeing likely indicates that your audio collection
> requires a few more bits to represent well than the collection the
> encoder was tuned against. It's not a cause for concern.
> 
> Hope that helps, and thanks for your interest in Opus.

Yes & thanks!

Ulrich