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Erik,<br>
<br>
The file indeed reached +/- 1 (one channel is the output of a
magnetic switched device, the audio signal is not strictly on-off
but it has a characteristic pattern that saturates).<br>
<br>
I performed the test you've suggested. I used Audacity to convert
32-float to 24-signed. The original size of 347 Mb reduced to 260
Mb, the expected 3/4 reduction. Then I compressed it with FLAC,
getting a 120 Mb file, and with Winrar, getting a 54 Mb file.<br>
<br>
However this may be an anomalous case, since I've tested other (16
bit) </font><font face="Courier New, Courier, monospace">audio
files and FLAC outperforms RAR.</font><font face="Courier New,
Courier, monospace"> <br>
<br>
</font>Regards,<br>
<br>
Federico<br>
<br>
<br>
<div class="moz-cite-prefix">On 22/01/2016 3:09, Erik de Castro Lopo
wrote:<br>
</div>
<blockquote
cite="mid:20160122170918.ffaa17d93eb19caa7e759ef3@mega-nerd.com"
type="cite">
<pre wrap="">Federico Miyara wrote:
</pre>
<blockquote type="cite">
<pre wrap="">
Dear all,
I have a wav file that when I try to encode with the FLAC Frontend, I
get "ERROR: unsupported format type 3".
</pre>
</blockquote>
<pre wrap="">
WAV format 3 is 32 bit IEEE float which is not supported by FLAC.
</pre>
<blockquote type="cite">
<pre wrap="">When I open it with an audio editor I find it is 44100 / 32 bit.
</pre>
</blockquote>
<pre wrap="">
32 bit *floating point* values. WAV files can also contain 32 bit (integer)
PCM.
</pre>
<blockquote type="cite">
<pre wrap="">I
requantized it to 16 bit using the default dither and then compressed it
</pre>
</blockquote>
<pre wrap="">
Maybe requantizing to 24 bit might have made more sense (and 24 bit PCM
is handled by FLAC).
</pre>
<blockquote type="cite">
<pre wrap="">However, as a last attempt, I used Winrar on the original file and to my
surprise it was compacted to 79 Mb, only about 33% more than the FLAC
version representing a file with half the data.
</pre>
</blockquote>
<pre wrap="">
If the orignal 32 bit IEEE float file had been normalized so that all
sample values are between -1.0 and +1.0 then the exponent part of each
floating point value (8 bits out of 32 bits) would have been identical
resulting in a very significant opportunity for a data compressor like
WinRAR to do it's work.
A much better (fairer?) comparison would be to compare how WinRAR compresses
a 24 bit PCM WAV file in comparison to FLAC.
Erik
</pre>
</blockquote>
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