[alsa-devel] [PATCH] firewire-lib: Use IEC 61883-6 compliant labels for Raw Audio data

[Takashi Iwai]

At Mon,  2 Jun 2014 01:50:16 +0900,
Takashi Sakamoto wrote:
> 
> According to AM824 in IEC 61883-6:2002, 2 bits in LSB of label for Raw Audio
> data means Valid Length Code (VBL). Ths value is:
> - b00 for 24 bits sample (label is 0x40)
> - b01 for 20 bits sample (label is 0x41)
> - b10 for 16 bits sample (label is 0x42)
> 
> But current firewire-lib apply 24 bits label for both of 16/24 bits samples.
> 
> As long as developers investigate BeBoB/Fireworks/OXFW/Dice, all of them
> have a behaviour to ignore the label. They can generate correct sound even
> if firewire-lib gives wrong label (i.e. 0xff). On BeBoB, this is not only
> for Raw Audio data channel, but also for IEC 60958 Conformant data channel.
> 
> So there is little possibility of regression.
> 
> Acked-by: Clemens Ladisch <clemens at ladisch.de>
> Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>

Thanks, applied.


Takashi

> ---
>  sound/firewire/amdtp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
> index 31dd1cf..f96bf4c 100644
> --- a/sound/firewire/amdtp.c
> +++ b/sound/firewire/amdtp.c
> @@ -418,7 +418,7 @@ static void amdtp_write_s16(struct amdtp_stream *s,
>  	for (i = 0; i < frames; ++i) {
>  		for (c = 0; c < channels; ++c) {
>  			buffer[s->pcm_positions[c]] =
> -					cpu_to_be32((*src << 8) | 0x40000000);
> +					cpu_to_be32((*src << 8) | 0x42000000);
>  			src++;
>  		}
>  		buffer += s->data_block_quadlets;
> -- 
> 1.8.3.2
>