IMA ADPCM and I2S

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Mental Mode
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IMA ADPCM and I2S

Post by Mental Mode » Mon 2020-02-10 12:22

Hi Guys,

I have 2 main questions about VS1063 that are probably common for VS1053.

1. IMA ADPCM should have a relation of 4:1 compression ratio compared to PCM. About the quality, ¿Is there so much distortion at 48kHz conversion rates? Does it wideband?
1.1 May I use lossless formats as G.711 (µ-law,A-law) at 48kHz sample rate being wideband?
1.2What's the bit depth of the audio once decoded?

2. About the I2S interface, If I decode the IMA ADPCM coming via serial for instance from another VS1063 or VS1053 will be the format converted to standard PCM prior being transmitted via I2S?
2.2 The I2S is simultaneous to analog output?

Maybe I'm mixing concepts but will be good for me to have these things clear before starting to go crazy.
Thanks for your help!
Best regards,
Mental Mode

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pasi
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Joined: Thu 2010-07-15 16:04

Re: IMA ADPCM and I2S

Post by pasi » Mon 2020-02-10 13:56

1.IMA ADPCM is ok for voice, but not that good for music, not even with higher samplerate. vs1063a has g.722, which is better. If you don't mind some latency and don't need full duplex, you can also use Ogg Vorbis and mp3.
1.1 Yes. 1.2 The decoded samples will be 16 bits.

2. I2S will transmit the same signal as the analog output and at the same time. All audio formats are decoded to linear PCM.
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