Need help in converting DVD player to Dolby receiver

[ashokec]

Hi
I have a DVD player with Dolby decoder.
I want to convert it so that it can decode 5.1 Dolby from SPDIF.
If you have any ideas please share.

Regards
Ashok

 

[linuxguru]

Hi
I have a DVD player with Dolby decoder.
I want to convert it so that it can decode 5.1 Dolby from SPDIF.

The usual configuration is to take the Dolby Digital AC-3 stream from SPDIF *output* of a DVD player, and use it to drive the SPDIF *input* of either a standalone Dolby 5.1 decoder or an integrated HT receiver.

The Dolby Digital decoder circuitry inside most DVD players doesn't usually decode the Dolby Digital AC-3 over SPDIF input internally. Typically, it's a multichannel DAC that's driven by the microcontroller directly, either over I2S or some other proprietary interface that carries the AC-3 stream.

It isn't that easy to take an AC-3 stream over SPDIF and use it to drive the internal Dolby decoder of a DVD player, though their are some codec chips that do have an SPDIF input with this capability, e.g. Realtek ALC888 or similar (typically used on PC motherboards).

 

[ashokec]

Hi

Thanks for the reply.
So you mean the micro control takes the input as a file and decodes AC3?
It won't take streaming input?

Regards

The usual configuration is to take the Dolby Digital AC-3 stream from SPDIF *output* of a DVD player, and use it to drive the SPDIF *input* of either a standalone Dolby 5.1 decoder or an integrated HT receiver.

The Dolby Digital decoder circuitry inside most DVD players doesn't usually decode the Dolby Digital AC-3 over SPDIF input internally. Typically, it's a multichannel DAC that's driven by the microcontroller directly, either over I2S or some other proprietary interface that carries the AC-3 stream.

It isn't that easy to take an AC-3 stream over SPDIF and use it to drive the internal Dolby decoder of a DVD player, though their are some codec chips that do have an SPDIF input with this capability, e.g. Realtek ALC888 or similar (typically used on PC motherboards).

 

[linuxguru]

So you mean the micro control takes the input as a file and decodes AC3?
It won't take streaming input?

The DVD digital decoder board will usually have a high-integration decoder ASIC on it, say from ESS, MediaTek or several other vendors. That chip handles a lot of digital functionality of reading a VOB, decrypting it, splitting it internally into video and audio streams, etc. Most of this happens internal to the decoder. At some point, the audio data stream is clocked out of the decoder into a DAC chip which generates the 5.1 analog outputs. - however, that stream doesn't usually go to the DAC as AC-3 over SPDIF, but over I2S or one of several other high-speed on-board data protocols. In addition, the decoder ASIC will also *output* an AC-3 over SPDIF stream that goes to the coax and TOSlink digital outputs of the player.

Most decoder or DAC chips in a DVD player do not have the functionality to take a Dolby digital AC-3 stream over SPDIF as *input*.