8 Dec
2014
8 Dec
'14
6:01 p.m.
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