[FFmpeg-devel] [PATCH 2/2] Fix side channels when XCh extension is present

Nick Brereton nick
Sun Jul 11 10:19:48 CEST 2010


On Sun, 2010-07-11 at 09:45 +0300, Kostya wrote:
> First, this is not unified diff, so it's not a patch in strict sense :)

Sorry about that - fixed! (& attached)

> And can you guarantee it's always correct mapping for channels (sorry,
> don't have specs at hand) i.e. it does not depend on amode?

s->channel_order_tab is a pointer to a row in the static channel mapping
tables at the top of the file, which already takes amode into account.

As this problem only occurs for DTS-ES matrix signals when there is a
discrete back-channel decoded (XCh) I think that the only significant
cases are amode=9 (i.e. 5 channels) with or without LFE. I have tested
samples of both of these cases which I think work correctly.
Unfortunately I'm not aware of a (publicly available) spec that covers
this extension.

It would also work for 4 channels + xch (although I'm not sure that's
used in practice); and also some of the 6 main channel cases - however I
doubt that's useful.

Nick
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