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From: thomas chen <tchen61@gmail.com>
To: Clemens Ladisch <clemens@ladisch.de>, alsa-devel@alsa-project.org
Subject: Re: I2S frame configuration
Date: Mon, 08 Dec 2014 13:03:17 -0500	[thread overview]
Message-ID: <5485E7E5.7020406@gmail.com> (raw)
In-Reply-To: <5485D96C.3020900@ladisch.de>


Thanks for the info... so it is possible for Asoc to handle such format...

So where does one specify number of bits in a FRAME/WORD (epsecially if 
we were to be master instead of slave ?)

and, how does one specify number of bits to ignore (before the valid data)

and also how many valid bits (ie size of data word) ???

Thanks...




On 12/8/2014 12:01 PM, Clemens Ladisch wrote:
> thomas chen wrote:
>> I am working on a ALSA interface to a particular codec over I2S
>>
>> the audio stream format is a bit peculiar...
>>
>> there are 24 BCLK cycle between transition of FSYNC...   howver, there are only 16 bit that are valid
>>
>> bit 0: ignore
>> bit 1-16:   valid pcm data (MSB....LSB)
>> bit 17-23: ignore
> This is the 'original' I²S format.  The format where the sample begins
> with the 1st BCLK usually is called left-justified (and uses the
> opposite FSYNC polarity).
>
> Having ignored bits is common.  (Typically, there are 32 BCLK cycles per
> sample.)
>
> In ASoC, this would be SND_SOC_DAIFMT_I2S and SND_SOC_DAIFMT_LEFT_J.
>
>
> Regards,
> Clemens

  reply	other threads:[~2014-12-08 18:03 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-08 15:37 I2S frame configuration thomas chen
2014-12-08 17:01 ` Clemens Ladisch
2014-12-08 18:03   ` thomas chen [this message]
2014-12-08 19:37     ` Lars-Peter Clausen
2014-12-09 13:51       ` thomas chen
2014-12-09 15:12         ` Lars-Peter Clausen

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