search

razzeee / xbmc-test

0 stars 0 forks source link

Real AC3 pass-through to SPDIF optical-out #4

Closed razzeee closed 7 years ago

razzeee commented 7 years ago

Reported by Gamester17 on 2 Oct 2003 14:11 UTC

Real/true AC3 pass-through to SPDIF optical-out By-pass the MPC sending audio stream out (no processing in XBMC whatsoever)

it is possible as both MS dashboard & DVDX 2.0 do this.

Quoting jmarshall on a couple obeservations:

  1. The XBox has onboard AC3 5.1 encoding in it's MCP- X (Audio processor). It can encode ac3 surround from 6 (or more if they're downmixed) channels of content.
    This allows game developers to easily create surround sound effects + soundtracks.

  2. There is currently no way that I know of to bypass the MCPx and write direct to the audio output buffers.
    This is clearly possible (Microsoft dash does it, as does DVD-X2) but I have found no documentation on how to do it, and the DVD-X2 guys have not got the code anymore.

This then leaves us with the following: We can either attempt to get the AC3 or DTS or whatever through the MCP-X unscathed, or decode in software and let the MCP-X reencode it. Unfortunately, the MCP-X upsamples everything to 24bit/48kHz which of course screws up any compressed stream. Thus, we are currently forced to decode in software and then let the MCP-X recode it after it's upsampled and done whatever else it wants. This is why DTS is currently not supported, as we can't decode it in software.

If anyone knows of a way to write direct to the audio output buffers BYPASSING the MCP-X, please get in contact and let me know. I'll implement it immediately.

Migrated-From: http://trac.kodi.tv/ticket/4

razzeee commented 7 years ago

Comment by monkeyhappy on 21 Nov 2003 15:38 UTC

Logged In: YES user_id=872682

This has been done

razzeee commented 7 years ago

Comment by gamester17 on 24 Nov 2003 10:19 UTC

Logged In: YES user_id=630186

Closing. btw is this fully sorted now?, thought the sync sound was done with a temporary workaround that would be permently fixed later?