Lossless SD-card player
This thread is about designing a WAV (FLAC) SD-card player for integration in (existing) DACs. It runs on a (divided) DAC master clock, and outputs I2S (64 bit / frame).
The advantage over CD players is the bit-perfect CD image, stored on a semiconductor memory card, that's able to reproduce exactly the same digital audio data, over and over again. Unlike CD players, the semiconductor memory is insensitive to shocks and vibrations, the card is also more robust compared to a CD that damages (scratches) easily. The SD-card player is absolutely silent (no moving parts).
The SD-card capacity also allows storage of multiple CDs or even an entire play-list. Due to the clock strategy and interface (I2S out), very low clock jitter and interference levels could be obtained. The interface / interlink related problems are eliminated.
The advantage over computer (PC) based digital audio sources is the absolute silent operation, low power consumption, very low interference levels, very low jitter, and The interface / interlink related problems are eliminated.
Are you thinking about something like this:
I have done the flac decoding in a tiny Xilinx FPGA, that receives streams (and playback commands) from an ethernet connection, and outputs the I2S.
I have actually had the same idea about a dedicated player, with a simple 2 lines lcd display and navigation keys for the operation, and reading data from usb stick or sd card.
I would be happy to share the FPGA source code, or we can co-work on a complete design ??
Here are some basic specs:
Support for max. 99 CDs and max. 99 tracks / CD on a single SD-card.
Support for CD and / or track shuffle.
FAT32 file system, provides support for high-capacity SD-cards.
Digital audio stored as WAV files.
Simple user interface, push buttons and blue 7-segments displays.
Remote control (optional).
CD increment / decrement (1 ... 99, 0 = CD shuffle).
Track increment / decrement (1 ... 99, 0 = track shuffle).
SD-card number support (1 ... 9999) for easy SD-card identification.
Philips I2S, 64 bits / frame.
44.1 KHz word clock, 2.8224 MHz bit clock (derived directly from master clock).
Single 5V (low-noise).
DSP clock = DAC master clock. The idea is to place the master clock as close to the DAC chip as possible, and route the buffered master clock to the DSP external clock input.
Main objective is to create an ideal digital audio source that provides very low jitter I2S signals, lowest possible interference, and is small enough to integrate in existing DACs. The integration is a must, as an I2S interface is used (short interlinks required), and the DSP must run on the DAC master clock.
I guess you know Koon's project from 2006. He's been there, done it.
He even made it work with a TI TAS5706 full digital amp.
Does that mean the end of the road for CDP's
probably yes. When i start using computer for music, CDs are only in the bigger boxes.
But, using SD card can be stored many CDs on 1 card.
To me this is practical solution. I will go for it, when is SD player ready.
Of course with DI1M.
Are you willing to publish the mentioned fpga design.
I'm curious about the flac decoding part in the fpga
Small fpga you say, which type ?
What are you using for playback on the pc ?
I wanted to start with this avnet evaluation board for some testing
|All times are GMT. The time now is 09:11 AM.|
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright ©1999-2015 diyAudio