Re: [ecasound] ecasound 2.0.4 released!

New Message Reply About this list Date view Thread view Subject view Author view Other groups

Subject: Re: [ecasound] ecasound 2.0.4 released!
From: Kai Vehmanen (
Date: Thu Feb 14 2002 - 00:03:06 EET

On Thu, 24 Jan 2002, Tobiah wrote:

>> One possibility is that n-track uses different layout for 24bit
>> samples. Ecasound (and ALSA and most soundcards) handle 24bit samples
> That would be it then. With n-track I am able to make samples that
> really only use 3 bytes/sample. It can also pad on the right or
> left with a byte, but I like the savings in disk space.

I just committed the following change to CVS:

- changed: s24_le and s24_be sample formats are interpreted
           as three-byte values, not as four-byte
           24-in-32bits values as before; to access
           unpacked 24bit data, use s32_le and s32_be
           formats instead

You should now be able to playback files saved in ntrack.
To access 24-in-32bits files, you can for instance do:

ecasound -f:s32_le,2,44100 -i typeselect,.raw,24bit_file.wav -o alsa

This works if the least significant byte has been zero padded. If the
align field is set correctly in the RIFF header (bits=24,
align=channel_count*3), ecasound can play these directly without need for

It's not possible to play 24bit files where the MS-byte is zero. On the
other hand these files are not standard RIFF PCM_WAVE files anymore.

> Because of the wBlockAlign field in the header,
> I don't object to padding 24bit samples to longs, but it is not
> clear from the above paragraph that this would be correct, and at least
> it suggests that a well behaved interpreter of wav files should catch the
> wBlockAlign size and be able to play true 3byte samples.

It's just that RIFF PCM_WAVE documents don't specify how the bits should
be physically laid out (ie. whether to pad extra msb or lsb bits).

Microsoft has issues a new RIFF-spec, WAVE_FORMAT_EXTENSIBLE, which tries
to solve these issues. Ecasound doesn't currently support it. Anyways, in
the extended format, valid sample bits are left-aligned and extra lsb bits
are padded to zero.

 Audio software for Linux!

-- To unsubscribe send message 'unsubscribe' in the body of the message to <>.

New Message Reply About this list Date view Thread view Subject view Author view Other groups

This archive was generated by hypermail 2b28 : Wed Feb 13 2002 - 23:55:19 EET