[mythtv] AC3 DVB Patch 3 - transform fix

Marcus Metzler mocm at mocm.de
Wed Jan 26 03:16:15 EST 2005


>>>>> "Mark" == Mark Anderson <markjanderson at mail.com> writes:

    Mark> Problem addressed by this patch: There are two related
    Mark> problems in transform.c preventing DVB AC3 audio from
    Mark> working:

    Mark> 1. The private stream header length was not being set,
    Mark> resulting in mpeg.c not extracting the AC3 payload
    Mark> correctly. 2. There is a call to "get_ac3info" which was not
    Mark> always succeeding, I believe because only part of the ac3
    Mark> payload was being searched. This resulted in the 4 byte ac3
    Mark> header not being reliably added to the mpeg stream.


    Mark> The fix: 1. Set the header length as needed.  2. Put a place
    Mark> holder 4 byte header into the stream and then rely on the
    Mark> code in send_ipack to put the correct values into the
    Mark> header.

Is the header even used by the mpeg decoder? Otherwise you would not
need to set it (except for the audio id). Of course you may need it if
you want to write a DVD, but in that case a lot more has to be done to
the stream (see dvb-replex).

    Mark> This patched should be reviewed by Marcus to be sure he
    Mark> agrees with the changes.
 Looks ok, if you want to address the problems you mentioned. I
haven't checked if it might break something else, but AFAICT it is ok.

Marcus

-- 
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| Dr. Marcus O.C. Metzler        |                                   |
| mocm at metzlerbros.de            | http://www.metzlerbros.de/        |
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