Perhaps only peripherally DIY but there's such a lot of computer expertise
here.

I was surprised today to see a reference to "a poor quality fifth-generation
mp3 file" - I thought that digital files (of whatever format) reproduced
exactly from generation to generation with no deterioration at all. Am I
mistaken? If mp3s do indeed get progressively worse when repeatedly dubbed
I'm going to have to rethink the audio project I'm currently working on.

Thanks.

On 18/05/2020 19:27, Bert Coules wrote:
Perhaps only peripherally DIY but there's such a lot of computer
expertise here.

I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all.Â* Am I mistaken?Â* If mp3s do indeed get
progressively worse when repeatedly dubbed I'm going to have to rethink
the audio project I'm currently working on.


MP3 is lossy, the compression removes detail you can never recover.

For editing you need a lossless format, WAV or FLAC or €¦?


--
djc

(–€Ì¿Ä¹Ì¯–€Ì¿ Ì¿)
No low-hanging fruit, just a lot of small berries up a tall tree.

Bert Coules wrote:

I thought that digital files (of whatever format) reproduced exactly
from generation to generation with no deterioration at all.

If you copy the file over and over, it'll retain the same quality, but
if you keep-re-encoding it, e.g. to mix in other channels each time,
you'll get gradually worse, if you can arrange it so you mix in all the
extra channels just once, so there's effectively only one extra
generation you'll get away without problems.

Andy Burns wrote:

If you copy the file over and over, it'll retain the same quality, but if
you keep-re-encoding it, e.g. to mix in other channels each time, you'll
get gradually worse...

Thanks for that. I'm using a multichannel mixer (MixPad) so I can keep all
the components separate and just export the mix down to a single file when
I'm finished. But since many of the separate tracks are mp3 files the
subsequent final mixdown does represent a first-generation dub of many of
them. But you confirm my suspicion that no deterioration is involved.

"DJC" wrote:

MP3 is lossy, the compression removes detail you can never recover.

Oh sure, I appreciate that. But I was concerned about subsequent copies
mp3 - mp3. Does the quality (compressed though it be) remain constant?

For editing you need a lossless format, WAV or FLAC or €¦?

Some of the files I'm working with are m4a which isn't a format I was
familiar with. Where do they stand in the quality hierarchy? Better than
mp3?

On 18/05/2020 19:27, Bert Coules wrote:
Perhaps only peripherally DIY but there's such a lot of computer
expertise here.

I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all.Â* Am I mistaken?Â* If mp3s do indeed get
progressively worse when repeatedly dubbed I'm going to have to rethink
the audio project I'm currently working on.

Thanks.
It depends. Obviously if you copy the file, it will be the same, but if
you encode to MP3, then re-encode that again for some reason, you get
even more loss and it will start to sound (even more?) horrible. If you
take a WAV, encode to MP3, then convert back to WAV, you don't get the
same file back.

Quite *why* you'd re-encode an MP3 is another matter.

If you take a lossless format (FLAC or WAV), then encode that to MP3
there's only one lot of loss.

No no no.
Every decode and encode of a lossy compression adds more losses.
If you want to edit mp3s then turn them into wav or flac files then you
will only have two generations of loss.
Brian

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"Bert Coules" wrote in message
o.uk...
Perhaps only peripherally DIY but there's such a lot of computer expertise
here.

I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all. Am I mistaken? If mp3s do indeed get progressively
worse when repeatedly dubbed I'm going to have to rethink the audio
project I'm currently working on.

Thanks.

Exactly, always do your edits in a lossless format and try to find a
lossless original if you can as well.
Brian

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Note this Signature is meaningless.!
"DJC" wrote in message ...
On 18/05/2020 19:27, Bert Coules wrote:
Perhaps only peripherally DIY but there's such a lot of computer
expertise here.

I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all. Am I mistaken? If mp3s do indeed get progressively
worse when repeatedly dubbed I'm going to have to rethink the audio
project I'm currently working on.


MP3 is lossy, the compression removes detail you can never recover.

For editing you need a lossless format, WAV or FLAC or .?


--
djc

(??L??? ?)
No low-hanging fruit, just a lot of small berries up a tall tree.

Basically if you decode to wav then re encode to mp3 every single time you
change a file then it will sound terrible in very short order.
Brian

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"Bert Coules" wrote in message
o.uk...
"DJC" wrote:

MP3 is lossy, the compression removes detail you can never recover.

Oh sure, I appreciate that. But I was concerned about subsequent copies
mp3 - mp3. Does the quality (compressed though it be) remain constant?

For editing you need a lossless format, WAV or FLAC or .?

Some of the files I'm working with are m4a which isn't a format I was
familiar with. Where do they stand in the quality hierarchy? Better than
mp3?

Well its still not clear to me that you are not re encoding.
For example if you import all the sounds you need all will have been
decoded. When you do a mix it will be still not re encoded. Save a non
compressed master of this intermediate mix, then save your new mp3. If
changes are then required go back to the uncompressed version and add to
that, not the mp3.
Or use Reaper and simply save the project and do the editing afresh, but
that software is really hard to grasp and not good for simple stuff.
Brian

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Note this Signature is meaningless.!
"Bert Coules" wrote in message
o.uk...
Andy Burns wrote:

If you copy the file over and over, it'll retain the same quality, but if
you keep-re-encoding it, e.g. to mix in other channels each time, you'll
get gradually worse...

Thanks for that. I'm using a multichannel mixer (MixPad) so I can keep all
the components separate and just export the mix down to a single file when
I'm finished. But since many of the separate tracks are mp3 files the
subsequent final mixdown does represent a first-generation dub of many of
them. But you confirm my suspicion that no deterioration is involved.

Brian Gaff wrote:

...and try to find a lossless original if you can as well.

That's the tricky bit unfortunately, in some cases, at least.

Brian Gaff wrote:

Save a non compressed master of this intermediate mix, then save your
new mp3. If changes are then required
go back to the uncompressed version and add to that, not the mp3.

That's essentially what I'm doing.

Or use Reaper and simply save the project and do the editing afresh, but
that software is really hard to grasp and not good for simple stuff.

I'm not familiar with Reaper and while I wouldn't exactly categorise what
I'm doing as simple, I'd prefer to stick to software that I'm familiar with.
But Reaper sounds interesting and I shall give it a look, thanks.

Chris Bartram wrote:

Quite *why* you'd re-encode an MP3 is another matter.

Does saving my MixPad mixes (which include quite a few mp3 tracks) to single
mp3 files mean that I'm re-encoding those particular elements?

On 18/05/2020 20:20, Bert Coules wrote:
"DJC" wrote:

MP3 is lossy, the compression removes detail you can never recover.

Oh sure, I appreciate that.Â* But I was concerned about subsequent copies
mp3 - mp3.Â* Does the quality (compressed though it be) remain constant?


If you simply copy the file, then you will have an identical file in the
same way as copying any other digital file.

The only way you would introduce further quality loss is to in some way
re-encode it, transcode it, or reconvert an analogue capture etc.


For editing you need a lossless format, WAV or FLAC or €¦?

Some of the files I'm working with are m4a which isn't a format I was
familiar with.Â* Where do they stand in the quality hierarchy?Â* Better
than mp3?

Its a successor to MP3, generally better results for the same bit rate,
but still a "lossy" format.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

Its a successor to MP3, generally better results for the same bit rate,
but still a "lossy" format.

Ah, right. Thanks, John.

On 18/05/2020 20:46, Chris Bartram wrote:
Quite *why* you'd re-encode an MP3 is another matter.
many non computer devices (some Tvs, cars) don't understand anything else..

--
No Apple devices were knowingly used in the preparation of this post.

Bert Coules wrote:

Brian Gaff wrote:

try to find a lossless original if you can as well.

That's the tricky bit

Or import all your MP3s to a lossless format, that won't degrade
anything, then produce your project, and do a single export to MP3/M4A
at the end (keep a lossless copy around too).

On 19/05/2020 08:13, Andy Burns wrote:
Bert Coules wrote:

Brian Gaff wrote:

try to find a lossless original if you can as well.

That's the tricky bit

Or import all your MP3s to a lossless format, that won't degrade
anything, then produce your project, and do a single export to MP3/M4A
at the end (keep a lossless copy around too).

+1


--
Climate Change: Socialism wearing a lab coat.

Andy Burns wrote:

Or import all your MP3s to a lossless format, that won't degrade anything,
then produce your project, and do a single export to MP3/M4A at the end
(keep a lossless copy around too).

Following this discussion that's exactly the course I decided on, so thanks
for reinforcing it.

On 18/05/2020 19:27, Bert Coules wrote:
Perhaps only peripherally DIY but there's such a lot of computer
expertise here.

I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all.Â* Am I mistaken?

Yes. MP3 is a compressed audio stream uncompressed when you listen to
it. You can crop and do certain other things to it losslessly but in
general if you change things like amplitude slightly then it will be
recompressed with additional quantisation losses every time you do it.

Standard approach for audio as with JPEG images is to keep all the
intermediate working files in some lossless format like FLAC.

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

There are transcoders that can do the available MP3 lossless operations
directly on an MP3 stream to splice things together for example.

If mp3s do indeed get
progressively worse when repeatedly dubbed I'm going to have to rethink
the audio project I'm currently working on.

Yes. Although depending on your final quality requirements you might get
away with it if you keep the bitrate high enough.

Sound files are generally small enough that using FLAC isn't too bad.
Then you have a single generation lossy recoding right at the end.

There is a very slight advantage to using about the same compression
quality parameters as your original source material.

--
Regards,
Martin Brown

In article ,
Bert Coules wrote:
I was surprised today to see a reference to "a poor quality
fifth-generation mp3 file" - I thought that digital files (of whatever
format) reproduced exactly from generation to generation with no
deterioration at all. Am I mistaken? If mp3s do indeed get
progressively worse when repeatedly dubbed I'm going to have to rethink
the audio project I'm currently working on.

I'd have thought copying an MP3 file would result in a clone of the
original. Unless it is decoded then treated in some way, then re-recorded.

--
*Atheism is a non-prophet organization.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Bert Coules wrote:
Andy Burns wrote:

If you copy the file over and over, it'll retain the same quality, but
if you keep-re-encoding it, e.g. to mix in other channels each time,
you'll get gradually worse...

Thanks for that. I'm using a multichannel mixer (MixPad) so I can keep
all the components separate and just export the mix down to a single
file when I'm finished. But since many of the separate tracks are mp3
files the subsequent final mixdown does represent a first-generation dub
of many of them. But you confirm my suspicion that no deterioration is
involved.

In which case I'd say you will get some losses over the original MP3 file.
As to mix it with others means decoding and re-coding the final mix.

--
*No word in the English language rhymes with month, orange, silver,purple

Dave Plowman London SW
To e-mail, change noise into sound.

Martin Brown wrote:

Standard approach for audio as with JPEG images is to keep all the
intermediate working files in some lossless format like FLAC.

Thanks. On the subject of compression, the bulk of the files I'm working
with are m4a recordings of a male speaking voice and they have a huge and
impractical dynamic range. I was resigned to going through them (and there
are a lot) manually adjusting the levels, but could applying compression
achieve a decent quality result? I do need to retain the clarity and
unmuddyness they have at present. I've very little experience with
compression of audio files and would be grateful for any thoughts.

Thanks.

On 19/05/2020 16:21, Bert Coules wrote:
Martin Brown wrote:

Standard approach for audio as with JPEG images is to keepÂ* all the
intermediate working files in some lossless format like FLAC.

Thanks.Â* On the subject of compression, the bulk of the files I'm
working with are m4a recordings of a male speaking voice and they have a
huge and impractical dynamic range.Â* I was resigned to going through
them (and there are a lot) manually adjusting the levels, but could
applying compression achieve a decent quality result?Â* I do need to
retainÂ* the clarity and unmuddyness they have at present.Â* I've very
little experience with compression of audio files and would be grateful
for any thoughts.

yes. that should work if you have a decent package.
Audacity is not bad for that


Thanks.


--
€œThe fundamental cause of the trouble in the modern world today is that
the stupid are cocksure while the intelligent are full of doubt."

- Bertrand Russell

The Natural Philosopher wrote:

Yes. that should work if you have a decent package.
Audacity is not bad for that.

Thanks. I do have Audacity, and the mixer program I'm using (MixPad) also
has a built-in compressor. MixPad has a preset called "general voice level"
which I suppose should be OK but Audacity requires manipulating a slightly
daunting array of parameters. I suspect that this would give a better
result if only I knew what settings would be best.

I've found a couple of tutorials on compression for spoken word audio which
have given me some starting points. I'm getting quite a decent sound with
these settings in Audacity:

Threshold -60 dB
Noise floor -40 dB
Ratio 3:1
Attack time 0.01 secs
Release time 1 sec

I'll keep experimenting.

On Tue, 19 May 2020 16:21:33 +0100, Bert Coules wrote:

On the subject of compression, the bulk of the files I'm working with
are m4a recordings of a male speaking voice and they have a huge and
impractical dynamic range. I was resigned to going through them (and
there are a lot) manually adjusting the levels, but could applying
compression achieve a decent quality result?

How long is a peice of string? Depends how wide a dynamic range
you're having to deal with and what the loud bits are.

If the loud bits are coughs or laughs or shouting the chance are they
can be controlled well enough with a limiter after a compressor.

If the "normal" speech has a dynamic range of 10 to 20 db a
compressor set at 2:1 to 3:1 with around 6 dB of gain reduction
happening ought to work reasonably well.

Just looked at Audacity's compressor/limiter "effects" and they
aren't realtime. Being used to realtime, ie tweak and instantly
hear/see the result, non-realtime totaly throws me.

--
Cheers
Dave.

Dave Liquorice wrote:

How long is a piece of string?

Yes, I appreciate the point.

Depends how wide a dynamic range
you're having to deal with and what the loud bits are.

Mostly, Audacity shows the range as from -20 dB to -6 dB but there are
occasional peaks of 0dB or above. All the files are of a man speaking,
whispering, and sometimes shouting.

If the "normal" speech has a dynamic range of 10 to 20 db a
compressor set at 2:1 to 3:1 with around 6 dB of gain reduction
happening ought to work reasonably well.

Sorry, I'm not sure what you mean by 6 dB of gain reduction. How does that
relate to Audacity's parameters of threshold, noise floor, and ratio?

Just looked at Audacity's compressor/limiter "effects" and they
aren't realtime.

I can see how that would be useful. I suspect that realtime would need
rather more processing power than I have available though. What software do
you favour?

Dave Liquorice wrote:

If the "normal" speech has a dynamic range of 10 to 20 db a
compressor set at 2:1 to 3:1 with around 6 dB of gain reduction
happening ought to work reasonably well.

Dave, since my previous reply I've sussed out the Audacity compressor (it
took me a shameful while to realise that the reduction was marked on the
display's horizontal axis rather than the vertical one). I've been trying
various settings and discovered that for the material I'm working with I
need rather more than 6 dB reduction: 20 dB appears to be nearer the mark.
That's if I want to retain a good contrast between the loudest and softest
passages.

I'll keep experimenting.

On 20/05/2020 06:30, Bert Coules wrote:
Dave Liquorice wrote:

If the "normal" speech has a dynamic range of 10 to 20 db a
compressor set at 2:1 to 3:1 with around 6 dB of gain reduction
happening ought to work reasonably well.

Dave, since my previous reply I've sussed out the Audacity compressor
(it took me a shameful while to realise that the reduction was marked on
the display's horizontal axis rather than the vertical one).Â* I've been
trying various settings and discovered that for the material I'm working
with I need rather more than 6 dB reduction: 20 dB appears to be nearer
the mark. That's if I want to retain a good contrast between the loudest
and softest passages.

I'll keep experimenting.


Good one Bert. You have it sussed.

--
Socialism is the philosophy of failure, the creed of ignorance and the
gospel of envy.

Its inherent virtue is the equal sharing of misery.

Winston Churchill

In article ,
Bert Coules wrote:
Dave Liquorice wrote:

If the "normal" speech has a dynamic range of 10 to 20 db a
compressor set at 2:1 to 3:1 with around 6 dB of gain reduction
happening ought to work reasonably well.

Dave, since my previous reply I've sussed out the Audacity compressor (it
took me a shameful while to realise that the reduction was marked on the
display's horizontal axis rather than the vertical one). I've been trying
various settings and discovered that for the material I'm working with I
need rather more than 6 dB reduction: 20 dB appears to be nearer the mark.
That's if I want to retain a good contrast between the loudest and softest
passages.

I'll keep experimenting.

The Audacity compressor doesn't seem to work in the same way as the
analogue one I have. So experimenting is the only way.

With pro analogue compressors, you could usually just enter your favourite
settings for a given use, and expect it to be pretty well there.

Not really found a software one that acts in the same way.

--
*WOULD A FLY WITHOUT WINGS BE CALLED A WALK?

Dave Plowman London SW
To e-mail, change noise into sound.