Re: [RFC PATCH] audio: proper support for float samples in mixeng

[Zoltán Kővágó]

On 2020-02-03 11:00, Peter Maydell wrote:
> On Sun, 2 Feb 2020 at 19:39, Kővágó, Zoltán <address@hidden> wrote:
> > This adds proper support for float samples in mixeng by adding a new
> > audio format for it.
> >
> > Limitations: only native endianness is supported.
>
> Could you explain a bit more what this limitation means, please?
> In general QEMU behaviour shouldn't depend on the endianness
> of the host, ie we should byteswap where necessary.

None of the virtual sound cards support float samples (it looks like 
most of them only support 8 and 16 bit, only hda supports 32 bit), it is 
only used for the audio backends (i.e. host side).  In 
audiodev_to_audsettings we set endianness to AUDIO_HOST_ENDIANNESS, so 
audio backends should always use native endian.

So this limitation should only cause problems when an audio backend 
overrides the endian setting.  Wavcapture does it, but it does not 
support float.  Alsa, sdl, puleaudio and oss can also do it if for some 
weird reason it acquires a stream with a different endianness than 
requested.

Regards,
Zoltan