AC3 in Australia (Was Re: [mythtv] DVB 3.4 report)
markjanderson at mail.com
Sat Jan 8 02:30:17 EST 2005
For those that are interested, attached is a patch that allows AC3 audio to
work in Australia. All previous problems outlined in this thread have been
resolved, some via dirty hacks.
The stuttering I was experiencing was caused by the hack to mpeg.c. The
changes in mpeg.c treat all PRIVATE_STREAM_1 packets as AC3 audio with no
header (0x80), which appears to be what oz stations are transmitting.
However, transform.c doesn't realise this and was occasionally finding
PRIVATE_STREAM_1 packets that had 0x80 or 0x20 as the first byte and adding
an extra header to them, which created an invalid AC3 packet for the hacked
mpeg.c and resulting in the stutter. I have hacked transform.c to not put the
extra headers on which fixes the stutter problem. This of course is not a
workable solution in the long term since the hack will only work in aus
presumably. Maybe someone who knows more about mpeg.c and transform.c can
look at this and see if they can work it out?
The rest of the changes should be useful to everyone, including the new GUI
option to enable AC3 audio and the audio re-initialisation code when the
audio codec changes.
Note, I have only tried this with AC3 to SPDIF, i.e. not software AC3.
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