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Old 09-06-2011, 11:48 AM
"Casper Ti. Vector"
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

Recently I found that the `-b' and `-ab' options used for setting the
output bitrate in ffmpeg and libav have no effect on my Gentoo machine.
With Ubuntu (and the Medibuntu repository enabled), this does not
happen.

For example, for any `<bitrate>' I use in
% ffmpeg -ab <bitrate> -i test.ape test.mp3
I get only `test.mp3' in 64kbps bitrate (as default setting). It's
similar as for other audio/video formats and/or the `-b' option.

My Gentoo system is updated daily with global ~amd64 keyword in use. I
recently switched from ffmpeg to libav and they are both affected by
this issue.

Is anybody facing the same issue? Has anyone got any idea about the
possible causes and/or solutions? Please tell me if more information is
needed, thanks.

--
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Old 09-06-2011, 12:09 PM
Nikos Chantziaras
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

On 09/06/2011 02:48 PM, Casper Ti. Vector wrote:

Recently I found that the `-b' and `-ab' options used for setting the
output bitrate in ffmpeg and libav have no effect on my Gentoo machine.
With Ubuntu (and the Medibuntu repository enabled), this does not
happen.

For example, for any `<bitrate>' I use in
% ffmpeg -ab<bitrate> -i test.ape test.mp3
I get only `test.mp3' in 64kbps bitrate (as default setting). It's
similar as for other audio/video formats and/or the `-b' option.

My Gentoo system is updated daily with global ~amd64 keyword in use. I
recently switched from ffmpeg to libav and they are both affected by
this issue.

Is anybody facing the same issue? Has anyone got any idea about the
possible causes and/or solutions? Please tell me if more information is
needed, thanks.


When running ffmpeg, it says:

"This program is not developed anymore and is only provided for
compatibility. Use avconv instead (see Changelog for the list of
incompatible changes)."


So try with avconv instead. But for MP3, you should probably be using
LAME with a VBR quality setting instead.
 
Old 09-06-2011, 12:34 PM
"Casper Ti. Vector"
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

Some additional information: the `-ab' and `-b' options seems to be
broken on my machine, since they accepts any argument, even those which
will cause error in the case of Ubuntu, for example `@@' or so.

Nevertheless, the option parsing is not completely broken, because an
unknown option ffmpeg will directly trigger a error in ffmpeg on my
machine, but `-ab' and `-b' (as expected) do not.

On Tue, Sep 06, 2011 at 03:09:13PM +0300, Nikos Chantziaras wrote:
> When running ffmpeg, it says:
> "This program is not developed anymore and is only provided for
> compatibility. Use avconv instead (see Changelog for the list of
> incompatible changes)."

Forgot to mention, but avconv suffers from the same problem...

> So try with avconv instead. But for MP3, you should probably be using
> LAME with a VBR quality setting instead.

In fact I don't quite know what you mean in this sentence :|

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Old 09-06-2011, 02:42 PM
Michael Mol
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

On Tue, Sep 6, 2011 at 8:34 AM, Casper Ti. Vector
<caspervector@gmail.com> wrote:
> On Tue, Sep 06, 2011 at 03:09:13PM +0300, Nikos Chantziaras wrote:
>> So try with avconv instead. *But for MP3, you should probably be using
>> LAME with a VBR quality setting instead.
> In fact I don't quite know what you mean in this sentence :|

'lame' is an MP3 encoder. VBR is 'variable bitrate', which means that
high-information sections in the input stream get more bits in the
output bitstream, and low-information sections in the input stream get
fewer bits in the output bitstream. An encoded song might use 192Kb/s
for a few seconds, and then 32Kb/s for a second, and jump up to
256Kb/s for a quarter-second before dropping down to 128Kb/s--but
still sound to your ear like it was encoded at a constant bitrate of
256Kb/s. All so that audio fidelity is maintained when there's
something there to actually hear.

Or, more simply:
* 'lame' is an MP3 encoder
* 'VBR' stands for 'variable bitrate', and offers a better
size/quality tradeoff scale than saying "I want 192Kb/s"

--
:wq
 
Old 09-06-2011, 02:56 PM
"Casper Ti. Vector"
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

But VBR seems to be disabled with the command line I used...
And, whether VBR is enabled, the wrong parsing of the argument of
bitrate options indicate that some error must exist somewhere.

On Tue, Sep 06, 2011 at 10:42:06AM -0400, Michael Mol wrote:

> 'lame' is an MP3 encoder. VBR is 'variable bitrate', which means that
> high-information sections in the input stream get more bits in the
> output bitstream, and low-information sections in the input stream get
> fewer bits in the output bitstream. An encoded song might use 192Kb/s
> for a few seconds, and then 32Kb/s for a second, and jump up to
> 256Kb/s for a quarter-second before dropping down to 128Kb/s--but
> still sound to your ear like it was encoded at a constant bitrate of
> 256Kb/s. All so that audio fidelity is maintained when there's
> something there to actually hear.
>
> Or, more simply:
> * 'lame' is an MP3 encoder
> * 'VBR' stands for 'variable bitrate', and offers a better
> size/quality tradeoff scale than saying "I want 192Kb/s"

Thanks, I understand what LAME and VBR is, but was just mistook the idea
of the original sentence as "use the `lame' program instead of `ffmpeg'
or `libav'" :]

--
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valid from 2010 to 2013) from a key server.
 
Old 09-06-2011, 04:29 PM
Nikos Chantziaras
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

On 09/06/2011 05:56 PM, Casper Ti. Vector wrote:

Or, more simply:
* 'lame' is an MP3 encoder
* 'VBR' stands for 'variable bitrate', and offers a better
size/quality tradeoff scale than saying "I want 192Kb/s"


Thanks, I understand what LAME and VBR is, but was just mistook the idea
of the original sentence as "use the `lame' program instead of `ffmpeg'
or `libav'" :]


Actually, that's what I meant :-/ Use the 'lame' program. The package
is "media-sound/lame". After emerging it, you can encode a file with
"lame -V 0 input.wav"
 
Old 09-06-2011, 04:46 PM
Michael Mol
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

On Tue, Sep 6, 2011 at 12:29 PM, Nikos Chantziaras <realnc@arcor.de> wrote:
> On 09/06/2011 05:56 PM, Casper Ti. Vector wrote:
>>>
>>> Or, more simply:
>>> * 'lame' is an MP3 encoder
>>> * 'VBR' stands for 'variable bitrate', and offers a better
>>> size/quality tradeoff scale than saying "I want 192Kb/s"
>>
>> Thanks, I understand what LAME and VBR is, but was just mistook the idea
>> of the original sentence as "use the `lame' program instead of `ffmpeg'
>> or `libav'" :]
>
> Actually, that's what I meant :-/ *Use the 'lame' program. *The package is
> "media-sound/lame". *After emerging it, you can encode a file with "lame -V
> 0 input.wav"

You're talking past each other. Casper thought you meant 'lame' as an
adjective, not as a proper noun.

--
:wq
 
Old 09-06-2011, 11:27 PM
"Casper Ti. Vector"
 
Default libav/ffmpeg's bitrate options have no effect in Gentoo

OK, but I was actually converting an FLV file, and didn't want to use
both programs, especially when ffmpeg already has support for
libmp3lame.

Anyway, there must be some problem in ffmpeg/libav (probably) or
something else (less probable than the former) on my computer.

On Tue, Sep 06, 2011 at 07:29:56PM +0300, Nikos Chantziaras wrote:
> Actually, that's what I meant :-/ Use the 'lame' program. The package
> is "media-sound/lame". After emerging it, you can encode a file with
> "lame -V 0 input.wav"

--
Using GPG/PGP? Please get my current public key (ID: 0xAEF6A134,
valid from 2010 to 2013) from a key server.
 

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