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<div class="moz-cite-prefix">On 2/15/22 22:23, Scott Theisen wrote:<br>
</div>
<blockquote type="cite"
cite="mid:48e7a000-f1a3-f0a0-836b-c14f075e124d@gmail.com">
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Peter,<br>
<br>
My harmonization of mpegts-mythtv.* is almost complete. (This is
on top of my rebase/4.4m3 branch, but should have no issues being
applied on top of mythtv/FFmpeg/master.)<br>
<br>
See <a class="moz-txt-link-freetext"
href="https://github.com/ulmus-scott/FFmpeg/commits/harmonize"
moz-do-not-send="true">https://github.com/ulmus-scott/FFmpeg/commits/harmonize</a>
for the original commit order and <a
class="moz-txt-link-freetext"
href="https://github.com/ulmus-scott/FFmpeg/commits/harmonize2"
moz-do-not-send="true">https://github.com/ulmus-scott/FFmpeg/commits/harmonize2</a>
for reordered with problematic commits moved to the end.<br>
<br>
I have been testing with some of my local stations and the samples
from <a class="moz-txt-link-freetext"
href="https://code.mythtv.org/trac/ticket/13557"
moz-do-not-send="true">https://code.mythtv.org/trac/ticket/13557</a>
/ <a class="moz-txt-link-freetext"
href="https://github.com/MythTV/mythtv/issues/351"
moz-do-not-send="true">https://github.com/MythTV/mythtv/issues/351</a>
and everything is fine through <a moz-do-not-send="true"
href="https://github.com/ulmus-scott/FFmpeg/commit/c22901ac83f9955f3846d33f79f4ddb8a07aeb8d">mpegts-mythtv.c:
harmonize ff_parse_mpeg2_descriptor() part 1</a>.<br>
<br>
I have been banging my head against the brick wall that is
pat_cb() and pmt_cb(). (It started out fairly straightforward,
but dealing with those two functions and the 17 year old changes
buried under updates has been increasingly frustrating.)<br>
<br>
<a moz-do-not-send="true"
href="https://github.com/ulmus-scott/FFmpeg/commit/58cc290d552169f2388e83384e1a28a22a710ae7">mpegts-mythtv.c:
pmt_cb(): harmonize part 6</a> appears to actually work fine;
however, the logic for calling the <span class="pl-smi">streams_changed()
callback is wrong, so it isn't called when it was previously. <a
moz-do-not-send="true"
href="https://github.com/ulmus-scott/FFmpeg/commit/8a8dc3d5599bd61368c26ed410248cad20f7fa25">Correcting
it</a>, sort of (it updates on every different PMT, instead of
if the streams actually changed), causes a segmentation fault in
<a class="moz-txt-link-freetext"
href="https://github.com/MythTV/mythtv/blob/709d05c0d6928e927ea1b0cc2b2c46bc80d40055/mythtv/libs/libmythtv/decoders/avformatdecoder.cpp#L2652"
moz-do-not-send="true">https://github.com/MythTV/mythtv/blob/709d05c0d6928e927ea1b0cc2b2c46bc80d40055/mythtv/libs/libmythtv/decoders/avformatdecoder.cpp#L2652</a>
.<br>
<br>
I suspect that is because the PSIPTable does not create a copy
of its input data, which is then freed while the PMT table is
being accessed.<br>
<br>
<a moz-do-not-send="true"
href="https://github.com/ulmus-scott/FFmpeg/commit/6887b3127bcc2b8211e0fd7ab9828965ffe847f0">mpegts-mythtv.c:
pat_cb() harmonization part 3</a> causes a different
segmentation fault in FFmpeg (dump.c trying to read the
st->metadata AVDictionary for the "language"). I wouldn't
worry about this one right now since I feel pmt_cb() has a
higher priority, so ff_parse_mpeg2_descriptor() can be minimally
modified.<br>
<br>
<br>
Let me know if you want me to open another set of pull requests
with the "good" commits for easier testing.<br>
<br>
Any thoughts on how to complete the harmonization would also be
appreciated.<br>
<br>
Regards,<br>
<br>
Scott</span></blockquote>
<p>I don't think I can help much here. I have stayed away from the
internals of FFmpeg except where necessary to fix errors when
merging new versions. I do not have any understanding of the
internals of Transport Streams or why MythTV needs to make so many
changes to FFmpeg. The changes that were done are very old, as you
have noted, and were done by others who are no longer around. I
don't know if any other developers of MythTV have better insight
into this.</p>
<p>Peter<br>
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