Re: [Audacity-quality] Files imported with FFmpeg vs. native import

[Bill W. <bi...@go...>]

On 24-Nov-10, at 11:54 AM, Gale Andrews wrote:

<snip>


>
> I've already documented the known restrictions at Quality Preferences
> in the Manual:
> http://manual.audacityteam.org/index.php?title=Quality_Preferences
>
> The -devel thread ended up with what "could" be Audacity bugs  
> according
> to year-old Forum reports -  but they have never been tested and  
> followed
> up:
>
> 1 "if you import 24-bit Apple Lossless via Quick Time, nothing  
> happens -
>    no crash or corrupted file, but no error message either. I don't  
> know if
>    FFmpeg can import them (at 16-bit)"
>
> 2 "(FFmpeg) can't import 24 bit PCM WAV without corruption"
>
> Bill, do you have time to test 1) in SVN HEAD and other apps like  
> QuickTime
> or iTunes?

Audacity 1.3.13 Nov 21 2010 Mac PPC OS X 10.5.8.

Quality settings 32 bit float, 44100 Hz.

I can find no way to create a 24-bit Apple Lossless file. A 16-bit  
file imports as a 16-bit track into a 32-bit project.

>
> As for 2), on Win 7 in SVN HEAD using the latest
> "FFmpeg_2009_07_20_for_Audacity_on_Windows.exe", the left channel
> of 24 bit PCM stereo files is silent. I'd need to try different  
> versions of
> FFmpeg at the command line to see if it's an Audacity problem or one  
> with
> FFmpeg.
>

I used Audacity to export a track using "Other uncompressed files" and  
choosing WAV 24-bit signed PCM. Opening the file in QuickTime it shows  
as "24-bit Integer (little endian) Stereo 44.100 kHz".

Importing that file into Audacity using "Format: All supported files"  
it imports fine into a 32-bit track. If I choose "Format: FFmpeg  
compatible files" I get the same result - and the import dialog looks  
the same. Is Audacity reverting to "native" import in this situation?

-- Bill