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[Josh Gee <986529@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

I've been struggling with this bug and I'm beginning to wonder if
there's an error in the build environmnent for the Oneiric mythbuntu
repos.

The bug (on my system) consists of purple vertical lines and other
purple corruption at cut points when doing:

mythtranscode --mpeg2 --honorcutlist

These errors are definitely in the recording, as moving the resulting
file to a windows box also shows these artifacts (just using Windows
Media Player as a quick test)

I've tried transcoding PAL resolution recordings from a DVB-T tuner
using both 0.24.0+fixes.20110908 and 0.24.2+fixes.20120409

This bug report seems to describe the issue
http://code.mythtv.org/trac/ticket/10110 but I don't know if he was
using mythbuntu repos and he claimed that a 3rd party libav/ffmpeg
update solved his issue.  However, Mythtranscode as built in the
mythbuntu repos doesn't appear to link to 3rd party libav/ffmpeg, but
rather mythlibav.

This forum thread http://ubuntuforums.org/showthread.php?t=1944788
indicates the bug exists in the latest 0.25 mythbuntu repos as well, but
ONLY in Oneiric (11.10) builds.  I'm quoting the most relevant post
here:

(begin Quote}
"I am reasonably certain it is a MYTHBUNTU 11.10 issue and NOT a MythTV 0.25 issue.

This morning I did a fresh install of 10.04 on my master backend,
removing the 11.10 installation that was on it. I then brought MythTV up
to the same 0.25 level it was at under 11.10 with the repos.

I transcoded 17 recordings this morning, 100% success, not even so much
as a single blip in any of the "trouble" spots (commercial breaks or 50
second increments on 720p recordings) that I checked. Previously with
11.10, I had 100% failure with the purple lines issue."

(end Quote)

This research seems to point to either A) a dynamic linking connection
that is not apparent via ldd, or B) a significant difference between the
build environment of 10.04 vs 11.10 repos of mythbuntu.  Furthermore,
this error appears to impact 0.24.x as well as 0.25.x builds, but only
on 11.10.

The latest 0.24.2+fixes.20120409 gives errors that may or may not point
to the cause of this issue. These errors did not exist in 0.24.0+fixes,
though the purple corruption did:


QString::arg: Argument missing: "Frame 12 > 11. Corruption likely at pos: 11" , 901605888
2012-04-21 11:19:34.713 Frame 12 > 11. Corruption likely at pos: 11
QString::arg: Argument missing: "Frame 12 > 11. Corruption likely at pos: 11" , 907132148
2012-04-21 11:19:36.252 Frame 12 > 11. Corruption likely at pos: 11
QString::arg: Argument missing: "Frame 30 > 29. Corruption likely at pos: 29" , 912360240
2012-04-21 11:19:36.668 Frame 30 > 29. Corruption likely at pos: 29
2012-04-21 11:19:37.946 Junk in packet
QString::arg: Argument missing: "Frame 18 > 17. Corruption likely at pos: 17" , 957535512
2012-04-21 11:19:40.351 Frame 18 > 17. Corruption likely at pos: 17
2012-04-21 11:19:40.669 Junk in packet

I'm not familiar enough with the mythtv code to track down where this
error might be coming from.

It appears, based mostly on guesswork and a little reading about codecs,
that something is going wrong when mythtranscode attempts to insert
frames around a cut.  I haven't yet had time to see if I can work around
the bug by making sure I only cut at keyframes .

There is a chance this is an upstream bug or that something is being
dynamically linked in a way invisible to ldd.  However the difference
between the same mythtv version in the 10.04 and 11.10 repos
(irregardless of 0.24 or 0.25) seems to indicate that there might be a
problem in the build environment or possibly a package being statically
linked in 11.10 that differs from 10.04.

** Affects: mythbuntu
     Importance: Undecided
         Status: New


** Tags: 11.10 lossless mythranscode

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https://bugs.launchpad.net/bugs/986529

Title:
  Mythtranscode Lossless corruption Oneiric - Purple frames at cut
  points

Status in Mythbuntu, Ubuntu derivative focused upon MythTV:
  New

Bug description:
  I've been struggling with this bug and I'm beginning to wonder if
  there's an error in the build environmnent for the Oneiric mythbuntu
  repos.

  The bug (on my system) consists of purple vertical lines and other
  purple corruption at cut points when doing:

  mythtranscode --mpeg2 --honorcutlist

  These errors are definitely in the recording, as moving the resulting
  file to a windows box also shows these artifacts (just using Windows
  Media Player as a quick test)

  I've tried transcoding PAL resolution recordings from a DVB-T tuner
  using both 0.24.0+fixes.20110908 and 0.24.2+fixes.20120409

  This bug report seems to describe the issue
  http://code.mythtv.org/trac/ticket/10110 but I don't know if he was
  using mythbuntu repos and he claimed that a 3rd party libav/ffmpeg
  update solved his issue.  However, Mythtranscode as built in the
  mythbuntu repos doesn't appear to link to 3rd party libav/ffmpeg, but
  rather mythlibav.

  This forum thread http://ubuntuforums.org/showthread.php?t=1944788
  indicates the bug exists in the latest 0.25 mythbuntu repos as well,
  but ONLY in Oneiric (11.10) builds.  I'm quoting the most relevant
  post here:

  (begin Quote}
  "I am reasonably certain it is a MYTHBUNTU 11.10 issue and NOT a MythTV 0.25 issue.

  This morning I did a fresh install of 10.04 on my master backend,
  removing the 11.10 installation that was on it. I then brought MythTV
  up to the same 0.25 level it was at under 11.10 with the repos.

  I transcoded 17 recordings this morning, 100% success, not even so
  much as a single blip in any of the "trouble" spots (commercial breaks
  or 50 second increments on 720p recordings) that I checked. Previously
  with 11.10, I had 100% failure with the purple lines issue."

  (end Quote)

  This research seems to point to either A) a dynamic linking connection
  that is not apparent via ldd, or B) a significant difference between
  the build environment of 10.04 vs 11.10 repos of mythbuntu.
  Furthermore, this error appears to impact 0.24.x as well as 0.25.x
  builds, but only on 11.10.

  The latest 0.24.2+fixes.20120409 gives errors that may or may not
  point to the cause of this issue. These errors did not exist in
  0.24.0+fixes, though the purple corruption did:

  
  QString::arg: Argument missing: "Frame 12 > 11. Corruption likely at pos: 11" , 901605888
  2012-04-21 11:19:34.713 Frame 12 > 11. Corruption likely at pos: 11
  QString::arg: Argument missing: "Frame 12 > 11. Corruption likely at pos: 11" , 907132148
  2012-04-21 11:19:36.252 Frame 12 > 11. Corruption likely at pos: 11
  QString::arg: Argument missing: "Frame 30 > 29. Corruption likely at pos: 29" , 912360240
  2012-04-21 11:19:36.668 Frame 30 > 29. Corruption likely at pos: 29
  2012-04-21 11:19:37.946 Junk in packet
  QString::arg: Argument missing: "Frame 18 > 17. Corruption likely at pos: 17" , 957535512
  2012-04-21 11:19:40.351 Frame 18 > 17. Corruption likely at pos: 17
  2012-04-21 11:19:40.669 Junk in packet

  I'm not familiar enough with the mythtv code to track down where this
  error might be coming from.

  It appears, based mostly on guesswork and a little reading about
  codecs, that something is going wrong when mythtranscode attempts to
  insert frames around a cut.  I haven't yet had time to see if I can
  work around the bug by making sure I only cut at keyframes .

  There is a chance this is an upstream bug or that something is being
  dynamically linked in a way invisible to ldd.  However the difference
  between the same mythtv version in the 10.04 and 11.10 repos
  (irregardless of 0.24 or 0.25) seems to indicate that there might be a
  problem in the build environment or possibly a package being
  statically linked in 11.10 that differs from 10.04.

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