[MPlayer-dev-eng] [PATCH] Fix sndio playback of 24 bit/sample audio.

[Alexandre Ratchov]

On Tue, Mar 11, 2014 at 07:57:56PM +0100, Reimar Döffinger wrote:
> Setting bps correctly is necessary since otherwise
> sndio defaults to 4 bps (instead of 3) for 24 bit audio.
> Setting msb will also allow playback if sndio also ignores
> our preferences and requests 4 bps input with 24 significant
> bits.
> 
> Patch by Alexandre Ratchov [alex caoua org] with
> additional comments by me.
> ---
>  libao2/ao_sndio.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/libao2/ao_sndio.c b/libao2/ao_sndio.c
> index f04115e..013d78a 100644
> --- a/libao2/ao_sndio.c
> +++ b/libao2/ao_sndio.c
> @@ -103,6 +103,10 @@ static int init(int rate, int channels, int format, int flags)
>      }
>      sio_initpar(&par);
>      par.bits = af_fmt2bits(format);
> +    par.bps = (par.bits + 7) >> 3;
> +    // normally bits == 8*bps so this makes no difference
> +    // but we can support more formats for msb == 1, see "if" below
> +    par.msb = 1;
>      par.sig = (format & AF_FORMAT_SIGN_MASK) == AF_FORMAT_SI;
>      if (par.bits > 8)
>          par.le = (format & AF_FORMAT_END_MASK) == AF_FORMAT_LE;
> @@ -118,7 +122,8 @@ static int init(int rate, int channels, int format, int flags)
>          mp_msg(MSGT_AO, MSGL_ERR, "ao2: couldn't get params\n");
>          goto err_out;
>      }
> -    if (par.bps != SIO_BPS(par.bits)) {
> +    // we do not care if LSBs are discarded
> +    if (par.bits < 8 * par.bps && !par.msb) {
>          mp_msg(MSGT_AO, MSGL_ERR, "ao2: unsupported format\n");
>          goto err_out;
>      }

the comments clearly express the intent, thanks.

-- Alexandre