Re: Wav to Mp3 leads to an mp3 file that has a longer duration

[Martin Ratinaud <martinratinaud@gmail.com>]

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Hi Jeremy and thanks for the quick answer (and sorry for the not very
precise report)

- I'm on OSX Mojave 10.14.6
- sox has been installed through brew `brew install sox`
- `sox --version` gives `sox:      SoX v`
- `brew info sox`gives

```

sox: stable 14.4.2 (bottled)

SOund eXchange: universal sound sample translator

https://sox.sourceforge.io/

/usr/local/Cellar/sox/14.4.2_3 (23 files, 1.8MB) *

  Poured from bottle on 2019-05-17 at 16:19:01

From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/sox.rb

==> Dependencies

Build: pkg-config ✔

Required: flac ✘, lame ✔, libpng ✔, libsndfile ✔, libvorbis ✔, mad ✔,
opusfile ✘

==> Analytics

install: 2,592 (30 days), 7,521 (90 days), 36,263 (365 days)

install-on-request: 2,436 (30 days), 7,051 (90 days), 32,403 (365 days)

build-error: 0 (30 days)

```



- SOX_OPTS is empty when I `echo $SOX_OPTS`

If I launch

```

sox -V3 vocals.wav vocals-V3.mp3

```


I get

```
sox:      SoX v
sox INFO formats: detected file format type `wav'

Input File     : 'vocals.wav'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
File Size      : 31.8M
Bit Rate       : 1.41M
Sample Encoding: 16-bit Signed Integer PCM
Endian Type    : little
Reverse Nibbles: no
Reverse Bits   : no

sox INFO sox: Overwriting `vocals-V3.mp3'
sox INFO mp3: using MP3 encoding defaults

Output File    : 'vocals-V3.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 24-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
Sample Encoding: MPEG audio (layer I, II or III)
Comment        : 'Processed by SoX'

sox INFO sox: effects chain: input        44100Hz  2 channels
sox INFO sox: effects chain: output       44100Hz  2 channels
```

Which seems good but when I do

```
soxi vocals-V3.mp3
```

I still get a different number of samples and duration

```
Input File     : 'vocals-V3.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.04 = 7939544 samples = 13502.6 CDDA sectors
File Size      : 2.88M
Bit Rate       : 128k
Sample Encoding: MPEG audio (layer I, II or III)
```

I notice that the precision is different and if I launch

```
sox -V3 vocals.wav -b 24 vocals-V3.mp3
```

It ends up with the same result

```
sox:      SoX v
sox INFO formats: detected file format type `wav'

Input File     : 'vocals.wav'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
File Size      : 31.8M
Bit Rate       : 1.41M
Sample Encoding: 16-bit Signed Integer PCM
Endian Type    : little
Reverse Nibbles: no
Reverse Bits   : no

sox WARN formats: mp3 can't encode to 24-bit
sox INFO mp3: using MP3 encoding defaults

Output File    : 'vocals-V3.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 24-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
Sample Encoding: MPEG audio (layer I, II or III)
Comment        : 'Processed by SoX'

sox INFO sox: effects chain: input        44100Hz  2 channels
sox INFO sox: effects chain: output       44100Hz  2 channels
```

but

```
soxi vocals-V3.mp3
```

still gives

```
Input File     : 'vocals-V3.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.04 = 7939544 samples = 13502.6 CDDA sectors
File Size      : 2.88M
Bit Rate       : 128k
Sample Encoding: MPEG audio (layer I, II or III)
```

Here a try with V4 ```sox -V4 vocals.wav vocals-V4.mp3 && soxi
vocals-V4.mp3```

```
sox:      SoX v
time:     Jan  9 2019 13:31:37
uname:    Darwin MBP-de-Martin 18.7.0 Darwin Kernel Version 18.7.0: Tue Aug
20 16:57:14 PDT 2019; root:xnu-4903.271.2~2/RELEASE_X86_64 x86_64
compiler: gcc 4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.11.45.5)
arch:     1288 48 88 L
sox INFO formats: detected file format type `wav'
sox DBUG wav: Searching for 66 6d 74 20
sox DBUG wav: WAV Chunk fmt
sox DBUG wav: Searching for 64 61 74 61
sox DBUG wav: WAV Chunk data
sox DBUG wav: Reading Wave file: Microsoft PCM format, 2 channels, 44100
samp/sec
sox DBUG wav:         176400 byte/sec, 4 block align, 16 bits/samp,
31752000 data bytes
sox DBUG wav:         7938000 Samps/chans
sox DBUG wav: Searching for 4c 49 53 54

Input File     : 'vocals.wav'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
File Size      : 31.8M
Bit Rate       : 1.41M
Sample Encoding: 16-bit Signed Integer PCM
Endian Type    : little
Reverse Nibbles: no
Reverse Bits   : no

sox DBUG mp3: -C option is inf
sox INFO mp3: using MP3 encoding defaults

Output File    : 'vocals-V4.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 24-bit
Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
Sample Encoding: MPEG audio (layer I, II or III)
Comment        : 'Processed by SoX'

sox INFO sox: effects chain: input        44100Hz  2 channels (multi) 16
bits 00:03:00.00
sox INFO sox: effects chain: output       44100Hz  2 channels (multi) 24
bits 00:03:00.00
sox DBUG sox: start-up time = 0.001929

Input File     : 'vocals-V4.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.04 = 7939544 samples = 13502.6 CDDA sectors
File Size      : 2.88M
Bit Rate       : 128k
Sample Encoding: MPEG audio (layer I, II or III)
```


And same with V5, V6 etc..

For  the trimming
I noticed there are 1544 more samples in the resulting mp3 file, so I tried
to trim them using this command

```
sox -V3 vocals.mp3 vocals-trimmed.mp3 trim 1544s && soxi vocals-trimmed.mp3
```


which gives

```
sox:      SoX v

Input File     : 'vocals.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.04 = 7939544 samples = 13502.6 CDDA sectors
File Size      : 2.88M
Bit Rate       : 128k
Sample Encoding: MPEG audio (layer I, II or III)

sox INFO sox: Overwriting `vocals-trimmed.mp3'
sox INFO mp3: using MP3 encoding defaults

Output File    : 'vocals-trimmed.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 24-bit
Sample Encoding: MPEG audio (layer I, II or III)
Comment        : 'Processed by SoX'

sox INFO sox: effects chain: input        44100Hz  2 channels
sox INFO sox: effects chain: trim         44100Hz  2 channels
sox INFO sox: effects chain: output       44100Hz  2 channels

Input File     : 'vocals-trimmed.mp3'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:03:00.01 = 7938397 samples = 13500.7 CDDA sectors
File Size      : 2.88M
Bit Rate       : 128k
Sample Encoding: MPEG audio (layer I, II or III)
```


So "it does not work" means, the resulting file is not exactly trimmed of
1544s as expected because there are 1147 left

It takes approximately 3s

I hope the description is clearer
Let me know if I can give you more information

Thanks

-----------------------------------------------------------------------
*Martin RATINAUD*
-----------------------------------------------------------------------


On Wed, Dec 11, 2019 at 9:39 PM Jeremy Nicoll - ml sox users <
jn.ml.sxu.88@wingsandbeaks.org.uk> wrote:

> On 2019-12-11 14:26, Martin Ratinaud wrote:
> > Hi all,
> >
> > I'm converting a file called vocals.wav to vocals.mp3
> >  vocals.wav
> > <
> https://drive.google.com/file/d/1he1eCJag1G8iGkgL932jy_mXuLT_khGM/view?usp=drive_web
> >
> > For this I'm using this command
> >
> > ```
> > sox vocals.wav vocals.mp3
> > ```
> > and here is the result of the corresponding files
> >
> > - original file
> > ```
> > soxi /Users/martin/Downloads/split-test/vocals.wav
> >
> > Input File     : '/Users/martin/Downloads/split-test/vocals.wav'
> > Channels       : 2
> > Sample Rate    : 44100
> > Precision      : 16-bit
> > Duration       : 00:03:00.00 = 7938000 samples = 13500 CDDA sectors
> > File Size      : 31.8M
> > Bit Rate       : 1.41M
> > Sample Encoding: 16-bit Signed Integer PCM
> > ```
> >
> > - converted file
> > ```
> > soxi /Users/martin/Downloads/split-test/vocals.mp3
> >
> > Input File     : '/Users/martin/Downloads/split-test/vocals.mp3'
> > Channels       : 2
> > Sample Rate    : 44100
> > Precision      : 16-bit
> > Duration       : 00:03:00.04 = 7939544 samples = 13502.6 CDDA sectors
> > File Size      : 2.88M
> > Bit Rate       : 128k
> > Sample Encoding: MPEG audio (layer I, II or III)
> > ```
> >
> > You can see that the duration is not the same which is weird and the
> > number
> > of samples also changed.
> > In fact, 1544 samples have been added to the beginning of the file
>
>
> Which version of sox, on what OS?
> Did you build the sox binary yourself or download it from somewhere?
>
> Although you say the command was just
>
>    sox vocals.wav vocals.mp3
>
> sox can also incorporate values of environment variables.  Is there any
> chance that on your OS the command has included any other parameters?
> See the 'SOX_OPTS' section of the manual.
>
>
> If you reissue the command, as eg
>
>    sox -V3 vocals.wav vocals002.mp3
>
> (or even -V4 or more) do any of the info messsages give any clues?  Is
> the
> result file the same size as your one?
>
>
>
>
> > If I try to launch `sox -V vocals.mp3 vocals-trimmed.mp3 trim 1544s` it
> > does not work
>
> You'll need to be more precise.  What sort of "not work"?   Does sox
> run?
> Does it produce any messages?  Is there a result file?  How long was it?
>
>
> --
> Jeremy Nicoll - my opinions are my own
>
>
> _______________________________________________
> Sox-users mailing list
> Sox-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/sox-users
>

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