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Can a .m4a audio file be converted into a .mp3 one losslessly?



 
 
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  #1  
Old April 2nd 19, 02:04 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
J. P. Gilliver (John)[_7_]
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Posts: 603
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

You'll need to have this fish in your ear. (First series, fit the first.)
Ads
  #2  
Old April 2nd 19, 03:04 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Paul[_32_]
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Posts: 11,873
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

J. P. Gilliver (John) wrote:
(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


https://en.wikipedia.org/wiki/Mp4a#A...ments_over_MP3

Improvements include:

* more sample rates (from 8 to 96 kHz) than MP3 (16 to 48 kHz);
* up to 48 channels (MP3 supports up to two channels in MPEG-1 mode
and up to 5.1 channels in MPEG-2 mode);
* arbitrary bit rates and variable frame length. Standardized CBR with bit reservoir;
* higher efficiency and simpler filter bank (rather than MP3's hybrid coding,
AAC uses a pure MDCT discrete cosine transform);
* higher coding efficiency for stationary signals
(AAC uses a blocksize of 1024 or 960 samples, allowing more
efficient coding than MP3's 576 sample blocks);
* higher coding accuracy for transient signals (AAC uses a
blocksize of 128 or 120 samples, allowing more accurate coding
than MP3's 192 sample blocks);
* possibility to use Kaiser-Bessel derived window function
to eliminate spectral leakage at the expense of widening the main lobe;
* much better handling of audio frequencies above 16 kHz;
* more flexible joint stereo (different methods
can be used in different frequency ranges);
* additional modules (tools) added to increase compression
efficiency: TNS, Backwards Prediction, PNS, etc. These modules
can be combined to constitute different encoding profiles.

In contrast to MP3's hybrid filter bank, AAC uses the
modified discrete cosine transform (MDCT) together with the
increased window lengths of 1024 or 960 points.

That doesn't strike me as an exact match. Transforming from
one to the other should sound different. Especially if one
throws away high frequencies in a different manner than the other.

A proclamation of "Try extract original audio stream" may be a
conversion from a compressed format to .wav, where the "try" is
certainly true. It still sounds like music. Then, running it
through the destination compressor, throws away content just
as the original conversion did. Neither is remotely similar
to the digitally recorded original PCM. You have two different
mutilations.

*******

https://en.wikipedia.org/wiki/MP3

"The song "Tom's Diner" by Suzanne Vega was the first song used
by Karlheinz Brandenburg to develop the MP3."

"An in-depth study of MP3 audio quality, sound artist and composer
Ryan Maguire's project "The Ghost in the MP3" isolates the sounds
lost during MP3 compression. In 2015, he released the track "moDernisT"
(an anagram of "Tom's Diner"), composed exclusively from the
sounds deleted during MP3 compression of the song "Tom's Diner"
"

So much for faithful reproduction.

Paul
  #3  
Old April 2nd 19, 04:18 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Big Al[_5_]
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Posts: 1,588
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On 4/2/19 9:04 AM, J. P. Gilliver (John) wrote:
(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


I use a lot of FLAC files. Mp3 loses a lot in translation.
https://www.cnet.com/news/what-is-fl...mp3-explained/

  #4  
Old April 2nd 19, 05:53 PM posted to microsoft.public.windowsxp.general
No_Name
external usenet poster
 
Posts: 627
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On Tue, 2 Apr 2019 14:04:55 +0100, "J. P. Gilliver (John)"
wrote:

(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


Audacity says it will handle M4A (free from Source Forge)
  #5  
Old April 2nd 19, 06:13 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Bill in Co[_3_]
external usenet poster
 
Posts: 303
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

J. P. Gilliver (John) wrote:
(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)
--


No, you can't. Because they are different formats. So there would be a
slight loss in converting it to mp3. BTW, m4a is the same as aac, so you
might try renaming the m4a to aac, and see if your converter recognizes it.
There are lots of programs out there that will reconvert these audio files,
but not losslessly, which is impossible.

One of my pet peeves is all the fuss that is made about how terrible it is
when you reconvert an audio file. I wonder if they have ever done it and
actually listened to it, and actually compared the differences. I have, and
the differences are typically inaudible, if you do it right. Just be sure
to keep the bitrate the same, or preferably higher, in the conversions.
But I have even reconverted an mp3 file at a modest bitrate of 128 kbps to
the same thing again, and you'd be hard pressed to hear any difference. Do
it several times, however, and all bets are off.

Of course, there are always those purists who insist on using FLAC files, or
those who insist that anything that has been digitized sounds inferior to,
say, vinyl records, simply because it was digitized, or even that those
expensive gold plated monster cables are required for the purest sound to
the loudspeakers. :-)

So my advice is let go of the mantra about lossless conversions, and just do
it and enjoy the music. But recode it at a minimum of 128 kbps, using
Joint Stereo mode. I also prefer to use a fix bitrate, but there are those
who like to use a variable bitrate, which is another story.


  #6  
Old April 2nd 19, 07:51 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Nil[_5_]
external usenet poster
 
Posts: 1,731
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On 02 Apr 2019, "J. P. Gilliver (John)" wrote in
alt.windows7.general:

(If so, with what software?)

I have one of many utilities for extracting the audio from video
clips (Pazera Free Audio Extractor); one of the options it offers
is "Try extract original audio stream" [sic].

I would like to use this, on the principle of doing as few
conversions as possible. (Many extractors do not make it clear
whether they are doing, or are recoding the audio; often they
offer selectable sample data rates, or sample rates, or file size,
which obviously mean they _do_ do an extra conversion stage.)


No, you can't. The conversion requires that the M4A be decompressed and
then re-compressed to MP3 format, and in the process incurring some
data loss.

If the original M4A is high enough quality and you convert to a high-
resolution you might not notice the difference. If you're going to be
editing the files you should consider converting the M4A to WAV format,
doing all your editing in that domain, then converting them to MP3 as
the very last stage.
  #7  
Old April 2nd 19, 09:05 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 2,679
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

In message , Paul
writes:
[]
https://en.wikipedia.org/wiki/Mp4a#A...ments_over_MP3

[]
In contrast to MP3's hybrid filter bank, AAC uses the
modified discrete cosine transform (MDCT) together with the
increased window lengths of 1024 or 960 points.

That doesn't strike me as an exact match. Transforming from


No, me neither. I'd thought maybe they were the same underneath, as so
many audio and video formats are these days, but sounds as if .m4a is
more modern (and thus almost certainly more efficient) than .mp3 is.
[]
A proclamation of "Try extract original audio stream" may be a
conversion from a compressed format to .wav, where the "try" is
certainly true. It still sounds like music. Then, running it


No, Pazera offers lots of different formats, including both
little-endian and big-endian WAV; "Try extract original" is at the
bottom of the list, so I am inclined to believe it does what it says. It
doesn't specify a type for that option, but most - possibly all - files
it has produced when I have selected that option have been .mp4 .

through the destination compressor, throws away content just
as the original conversion did. Neither is remotely similar
to the digitally recorded original PCM. You have two different
mutilations.


I grok that.
[]
So much for faithful reproduction.

Paul


Viewing on a spectrogram can be most revealing! Especially the cutoff: a
surprising number of files have a brickwall cutoff; 16 kHz is common,
13, 11, 10½ ... that's files I've received in digital form. Ones I've
made myself, e. g. by digitising from (analogue) records or tapes, I've
also found - especially for older material - there's often no _content_
above a surprisingly low frequency, other than tape hiss or (for 78s)
surface noise. (If in doubt, _high_ pass it and listen!) But that's
something of a side path from format conversion discussions.
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"OLTION'S COMPLETE, UNABRIDGED HISTORY OF THE UNIVERSE
Bang! ...crumple." - Jery Oltion
  #8  
Old April 2nd 19, 09:06 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Fokke Nauta[_4_]
external usenet poster
 
Posts: 587
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On 02/04/2019 17:18, Big Al wrote:
On 4/2/19 9:04 AM, J. P. Gilliver (John) wrote:
(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


I use a lot of FLAC files.Â*Â* Mp3 loses a lot in translation.
https://www.cnet.com/news/what-is-fl...mp3-explained/


+1

Fokke
  #9  
Old April 2nd 19, 09:08 PM posted to microsoft.public.windowsxp.general
No_Name
external usenet poster
 
Posts: 627
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On Tue, 02 Apr 2019 14:51:56 -0400, Nil
wrote:

On 02 Apr 2019, "J. P. Gilliver (John)" wrote in
alt.windows7.general:

(If so, with what software?)

I have one of many utilities for extracting the audio from video
clips (Pazera Free Audio Extractor); one of the options it offers
is "Try extract original audio stream" [sic].

I would like to use this, on the principle of doing as few
conversions as possible. (Many extractors do not make it clear
whether they are doing, or are recoding the audio; often they
offer selectable sample data rates, or sample rates, or file size,
which obviously mean they _do_ do an extra conversion stage.)


No, you can't. The conversion requires that the M4A be decompressed and
then re-compressed to MP3 format, and in the process incurring some
data loss.

If the original M4A is high enough quality and you convert to a high-
resolution you might not notice the difference. If you're going to be
editing the files you should consider converting the M4A to WAV format,
doing all your editing in that domain, then converting them to MP3 as
the very last stage.


I am not sure how that changes anything. It is still the equivalent to
an analog "copy of a copy".
I agree when you change formats you are uncompressing and
recompressing it tho. That uncompressed state is probably WAV anyway.
The idea of changing the file extension to AAC is worth a shot tho.
Some players will eat an AAC. You don't have much to lose because you
can always change it back.
(DOS is your friend here)
  #10  
Old April 2nd 19, 09:30 PM posted to microsoft.public.windowsxp.general
No_Name
external usenet poster
 
Posts: 627
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On Tue, 2 Apr 2019 22:06:38 +0200, Fokke Nauta
wrote:

On 02/04/2019 17:18, Big Al wrote:
On 4/2/19 9:04 AM, J. P. Gilliver (John) wrote:
(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


I use a lot of FLAC files.Â*Â* Mp3 loses a lot in translation.
https://www.cnet.com/news/what-is-fl...mp3-explained/


+1

Fokke


Storage is so cheap these days WAV is not that far out of reach and
that is about as good as sound gets if CD is the gold standard.
  #11  
Old April 2nd 19, 09:45 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 2,679
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

In message , Bill in Co
writes:
J. P. Gilliver (John) wrote:
(If so, with what software?)

[]
No, you can't. Because they are different formats. So there would be a
slight loss in converting it to mp3.


Yes, Paul's explained that.

BTW, m4a is the same as aac, so you
might try renaming the m4a to aac, and see if your converter recognizes it.


I've just tried. Unfortunately, neither my old Goldwave nor my old
WinAmp did, so I doubt my standalone player would. I just tried with
another .aac file I have, and old GoldWave still didn't like it, but old
WinAmp did, so there are obviously more than one kind of .aac file.

There are lots of programs out there that will reconvert these audio files,
but not losslessly, which is impossible.

One of my pet peeves is all the fuss that is made about how terrible it is
when you reconvert an audio file. I wonder if they have ever done it and
actually listened to it, and actually compared the differences. I have, and


I agree. It's the same as image files and the JPEG format; yes, I know
it loses on every save (unless you use JPEG lossless cropping or
rotation), but for _practical_ purposes, the loss is rarely visible, let
alone significant, at least at high enough resolutions. (I do genealogy,
and a large proportion of online images are only available in JPEG. I
often tweak and re-save - for example, highlighting a section - without
visible loss; I guess you could find the degradation if you looked for
it, but I think you'd have to look hard.)

Especially (for audio files) with (a) older humans (b) the sort of
speakers that are common these days, especially in e. g. laptops. I
generally don't trim if I can see there is content there even if I can't
hear it myself, or I could make even smaller files - because disc space
is so cheap nowadays.

the differences are typically inaudible, if you do it right. Just be sure
to keep the bitrate the same, or preferably higher, in the conversions.


Hmm, bitrate: I'd always (I think) go via WAV, with no compression (i.
e. raw).

But I have even reconverted an mp3 file at a modest bitrate of 128 kbps to
the same thing again, and you'd be hard pressed to hear any difference. Do


That's where we differ - I rarely use as _high_ a rate as 128kbps for
..mp3! 96kbps is about the highest I use normally. For 22050 Hz (which I
use if there's no content above 11 kHz) I don't think I've used over 48k
for mono, 64k for stereo.

it several times, however, and all bets are off.

Of course, there are always those purists who insist on using FLAC files, or
those who insist that anything that has been digitized sounds inferior to,
say, vinyl records,


Oh, purlease (-:.

simply because it was digitized, or even that those
expensive gold plated monster cables are required for the purest sound to
the loudspeakers. :-)


Gold plated _connectors_ have some use _if_ you're replugging often -
but that's mainly to avoid corrosion on the mating faces, not much to do
with any property of the gold itself. As for the cables themselves
between the connectors, I _do_ acknowledge the existence of skin effect
- high frequencies _do_ only travel in the surface layer of conductors -
but (a) this [the depth of the "skin"] _tends_ only to be relevant well
above audio frequencies, (b) unless you're using cables that are bare to
the air, i. e. if you use normal cables with a covering, copper's no
different; it's basically the corrosion problem again.

So my advice is let go of the mantra about lossless conversions, and just do
it and enjoy the music. But recode it at a minimum of 128 kbps, using
Joint Stereo mode. I also prefer to use a fix bitrate, but there are those
who like to use a variable bitrate, which is another story.

I've nothing against VBR (as long as the converter uses some sort of
look-ahead), but the old LAME encoder I use (and/or the GoldWave I use
it from) doesn't/don't have VBR.

--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

After all is said and done, usually more is said.
  #12  
Old April 2nd 19, 09:46 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 2,679
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

In message , "J. P. Gilliver (John)"
writes:
[]
No, Pazera offers lots of different formats, including both
little-endian and big-endian WAV; "Try extract original" is at the
bottom of the list, so I am inclined to believe it does what it says.
It doesn't specify a type for that option, but most - possibly all -
files it has produced when I have selected that option have been .mp4 .


Sorry, I meant .m4a there.
[]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

And on the question of authorship, I subscribe to the view that the plays were
not in fact written by Shakespeare but by someone of the same name.
- Hugh Bonneville (RT 2014/10/11-17)
  #13  
Old April 2nd 19, 09:49 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 2,679
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

In message , Nil
writes:
[]
If the original M4A is high enough quality and you convert to a high-
resolution you might not notice the difference. If you're going to be
editing the files you should consider converting the M4A to WAV format,
doing all your editing in that domain, then converting them to MP3 as
the very last stage.


Since the editor I use doesn't accept .m4a, I use Pazera's "extract to
WAV" function, and proceed from there.
[]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

And on the question of authorship, I subscribe to the view that the plays were
not in fact written by Shakespeare but by someone of the same name.
- Hugh Bonneville (RT 2014/10/11-17)
  #14  
Old April 2nd 19, 10:41 PM posted to microsoft.public.windowsxp.general,alt.windows7.general
Bill in Co[_3_]
external usenet poster
 
Posts: 303
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

J. P. Gilliver (John) wrote:
In message , Bill in Co
writes:
J. P. Gilliver (John) wrote:
(If so, with what software?)

[]
No, you can't. Because they are different formats. So there would be
a slight loss in converting it to mp3.


Yes, Paul's explained that.

BTW, m4a is the same as aac, so you
might try renaming the m4a to aac, and see if your converter recognizes
it.


I've just tried. Unfortunately, neither my old Goldwave nor my old
WinAmp did, so I doubt my standalone player would. I just tried with
another .aac file I have, and old GoldWave still didn't like it, but old
WinAmp did, so there are obviously more than one kind of .aac file.


It may have something to do with the licensing, OR you didn't install a
converter pack for Goldwave, if that option exists. With aac we're getting
into Apple territory here, and Apple likes to lock things down, as I recall.
But there are programs out there. I don't think it's due to the kind of aac
file, it's due to whether or not the converter has been added to the program
or not, and the licensing stuff

There are lots of programs out there that will reconvert these audio
files, but not losslessly, which is impossible.

One of my pet peeves is all the fuss that is made about how terrible it
is when you reconvert an audio file. I wonder if they have ever done it
and actually listened to it, and actually compared the differences. I
have, and


I agree. It's the same as image files and the JPEG format; yes, I know
it loses on every save (unless you use JPEG lossless cropping or
rotation), but for _practical_ purposes, the loss is rarely visible, let
alone significant, at least at high enough resolutions. (I do genealogy,
and a large proportion of online images are only available in JPEG. I
often tweak and re-save - for example, highlighting a section - without
visible loss; I guess you could find the degradation if you looked for
it, but I think you'd have to look hard.)


Yes, I was going to bring up the analogy with JPEGs, but you've already done
it. The purists out there would insist on never using a JPEG for anything.
:-) The analogy would be to only use WAV files for everything, with FLAC
being perhaps a close second. I can't imagine living with that limitation,
in terms of disk space, etc. However, if I were an audio engineer working
in the studio, that would of course be different. Since I use a portable
tiny mp3 player, disk space is still important to me. Come to think of it,
even on the HD too, as I have tons of audio files collected and stored there
over all the years, and there wouldn't be enough space for WAV files.

Especially (for audio files) with (a) older humans (b) the sort of
speakers that are common these days, especially in e. g. laptops. I
generally don't trim if I can see there is content there even if I can't
hear it myself, or I could make even smaller files - because disc space
is so cheap nowadays.

the differences are typically inaudible, if you do it right. Just be
sure to keep the bitrate the same, or preferably higher, in the
conversions.


Hmm, bitrate: I'd always (I think) go via WAV, with no compression (i.
e. raw).


When you convert one format to another, I think the intermediary step is WAV
anyways, so I'm not sure you gain anything by selecting WAV (since I believe
that step happens anyways as it's being converted from one format to the
other). However, if you intend to edit the file, then converting to WAV is
obviously the best idea.

But I have even reconverted an mp3 file at a modest bitrate of 128 kbps
to the same thing again, and you'd be hard pressed to hear any
difference. Do


That's where we differ - I rarely use as _high_ a rate as 128kbps for
.mp3! 96kbps is about the highest I use normally. For 22050 Hz (which I
use if there's no content above 11 kHz) I don't think I've used over 48k
for mono, 64k for stereo.


Well, I'm talking about good quality music files here on a decent sound
system,, not just stuff off the radio. For the latter, I agree.

it several times, however, and all bets are off.

Of course, there are always those purists who insist on using FLAC
files, or those who insist that anything that has been digitized sounds
inferior to, say, vinyl records,


Oh, purlease (-:.


And I didn't even get into the so called purists who insist that vacuum tube
amplifiers have much less distortion than any transistor amplifiers (but
which was admitedly true back in the 1960's and early 1970s, as I do
recall).

simply because it was digitized, or even that those
expensive gold plated monster cables are required for the purest sound to
the loudspeakers. :-)


Gold plated _connectors_ have some use _if_ you're replugging often -
but that's mainly to avoid corrosion on the mating faces, not much to do
with any property of the gold itself. As for the cables themselves
between the connectors, I _do_ acknowledge the existence of skin effect
- high frequencies _do_ only travel in the surface layer of conductors -
but (a) this [the depth of the "skin"] _tends_ only to be relevant well
above audio frequencies, (b) unless you're using cables that are bare to
the air, i. e. if you use normal cables with a covering, copper's no
different; it's basically the corrosion problem again.


Yup, only for the corrosion thing. But some think the gold makes better
sound. :-)

So my advice is let go of the mantra about lossless conversions, and
just do it and enjoy the music. But recode it at a minimum of 128
kbps, using Joint Stereo mode. I also prefer to use a fix bitrate, but
there are those who like to use a variable bitrate, which is another
story.

I've nothing against VBR (as long as the converter uses some sort of
look-ahead), but the old LAME encoder I use (and/or the GoldWave I use
it from) doesn't/don't have VBR.


VBR files can (admitely rarely) be problematic for some audio utilities or
some audio programs, which is why I stick with the simple CBR format, which
works flawlessly on everything, without any hidden surprises along the way.
It has happened to me on rare occasion in the past, but I don't recall now
the particulars. I just consider using CBR a form of insurance.

I have a similar philosophy about making backup images for my HD. I
*always* do a complete image backup - no incrementals. I just don't trust
it. Everything is contained in only one file - there is only one file to go
wrong, if it goes wrong, and there are no other dependencies. :-)


  #15  
Old April 3rd 19, 01:01 AM posted to microsoft.public.windowsxp.general,alt.windows7.general
Shadow
external usenet poster
 
Posts: 1,638
Default Can a .m4a audio file be converted into a .mp3 one losslessly?

On Tue, 2 Apr 2019 14:04:55 +0100, "J. P. Gilliver (John)"
wrote:

(If so, with what software?)

I have one of many utilities for extracting the audio from video clips
(Pazera Free Audio Extractor); one of the options it offers is "Try
extract original audio stream" [sic].

I would like to use this, on the principle of doing as few conversions
as possible. (Many extractors do not make it clear whether they are
doing, or are recoding the audio; often they offer selectable sample
data rates, or sample rates, or file size, which obviously mean they
_do_ do an extra conversion stage.)

Mostly - possibly always, but that could be because most of the video
files I'm extracting from are .mp4 - it produces a .m4a audio file. My
old .mp3 player (actually it's a SatNav, but can be a .mp3 player too)
doesn't know .m4a. (Nor does the old [bought!] version of GoldWave I
use, but I can always get into that by having Pazera extract as .wav,
which though a conversion, I presume doesn't involve any loss.)

So: _does_ .m4a contain the same samples as .mp3 but with different
wrapper, or are they different? (If they are the same, anyone know an
audio extractor that extracts original [i. e. without conversion loss]
to .mp3?)


Mediainfo lite will tell you what the audio format is

http://www.codecguide.com/download_other.htm#mediainfo

Install, and right click on the movie and look at the "Audio"
section:

Example:

Audio
Format : AAC LC

-----------

Once you know the audio format use FFmpeg to extract the audio
file:

ffmpeg -i movie.mp4 -c:a copy movie.aac

Movie.aac will be the original, un-messed-up audio file.

If it's a mp3

ffmpeg -i movie.mp4 -c:a copy movie.mp3

Converting it to any other compressed format will be lossy.
Since no converting is done, the whole procedure, even for a
two hour movie, will take a few seconds. And the original MP4 will be
untouched.
HTH
[]'s
--
Don't be evil - Google 2004
We have a new policy - Google 2012
 




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