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Bug 599469 - resindvd: problems pre-rolling in the absence of audio
resindvd: problems pre-rolling in the absence of audio
Product: GStreamer
Classification: Platform
Component: gst-plugins-bad
git master
Other Linux
: Normal blocker
: 0.10.23
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Reported: 2009-10-24 08:45 UTC by Jan Schmidt
Modified: 2012-01-27 11:14 UTC
See Also:
GNOME target: ---
GNOME version: ---

autoconvert: Cache incoming new segment events and push to children. (3.78 KB, patch)
2009-10-25 17:37 UTC, Jan Schmidt
committed Details | Review
autoconvert: Support installing identity as the initial child (14.58 KB, patch)
2009-10-25 17:38 UTC, Jan Schmidt
committed Details | Review
resindvd: Set the new initial-identity property on autoconvert (1.05 KB, patch)
2009-10-25 17:39 UTC, Jan Schmidt
committed Details | Review
resdvdsrc: fix preroll wedge when no audio is present (1.10 KB, patch)
2012-01-19 15:41 UTC, Vincent Penquerc'h
none Details | Review
resindvd: fix preroll on titles with no audio track (5.22 KB, patch)
2012-01-20 15:36 UTC, Vincent Penquerc'h
none Details | Review
resindvd: fix preroll on titles with no audio track (5.40 KB, patch)
2012-01-22 17:37 UTC, Vincent Penquerc'h
committed Details | Review

Description Jan Schmidt 2009-10-24 08:45:36 UTC
Switching to autoconvert for handling the audio streams has introduced a regression on some DVDs. Sequences which move immediately to a still frame with no audio, or which play a long video sequence without audio no longer preroll.

Previously, it was the responsibility of the 'rsnaudiomunge' element to generate a fake audio pre-roll buffer in these cases, in response to new-segment update events. Since autoconvert caches events until the first caps are set (with the first audio data buffer) and it can plug a decoder, the new-segment events don't arrive in rsnaudiomunge.

One fix would be to have a property on autoconvert that makes it start with a plugged identity element, and replace it later when the audio arrives. I don't think that's desirable default behaviour for autoconvert of course.

A pre-requisite for supporting that would also be having autoconvert cache segment info and inform the elements about their segment with a NewSegment update delivered after the element is plugged.

I'll be producing a patch for this, unless someone can suggest a better approach?
Comment 1 Jan Schmidt 2009-10-25 17:37:01 UTC
Created attachment 146218 [details] [review]
autoconvert: Cache incoming new segment events and push to children.

Cache incoming new-segment info.

When installing a child element, inform it of the current segment info.
Comment 2 Jan Schmidt 2009-10-25 17:38:16 UTC
Created attachment 146219 [details] [review]
autoconvert: Support installing identity as the initial child

Add the 'initial-identity' property, which inserts identity for
at startup for event passing, and replaces it with a new child
when the first buffer (and caps) actually arrives.
Comment 3 Jan Schmidt 2009-10-25 17:39:38 UTC
Created attachment 146220 [details] [review]
resindvd: Set the new initial-identity property on autoconvert
Comment 4 Olivier Crête 2009-10-27 13:06:07 UTC
Instead of adding an identity element, maybe it there should be "if (!subelement && let_buffers_through) gst_pad_push_event(srcpad, event)". And have a "let-non-buffers-through" property ? I don't think we want an identity left in there once the real elements are created.
Comment 5 Jan Schmidt 2009-10-27 14:09:26 UTC
That could work too. I might give it a try later.

Is there any reason to make it a configurable option, or should it just be the default behaviour? Can you provide any test cases for autoconvert so we can make sure it continues to work as originally intended?
Comment 6 Sebastian Dröge (slomo) 2011-12-05 08:27:21 UTC
This change is wrong, it causes newsegment events to arrive downstream before any caps are known. This must not happen and causes problems with autopluggers (and similar elements: playsinkvideoconvert for example).

Also this behaviour is now broken, see bug #665205 . Because identity (basetransform) now caches serialized events until the caps are known, the newsegment events never arrive on the srcpad of identity but is queued inside identity forever. Then autoconvert plugs the new, correct elements but no new newsegment event is sent to them that is also allowed to be pushed downstream.

This has to be solved differently, for example with a preroll buffer before autoconvert.
Comment 7 Sebastian Dröge (slomo) 2011-12-07 12:51:27 UTC
I've reverted this change now to at least have working playback of normal DVDs again. The best way to fix this would probably be to insert an raw, empty audio buffer for prerolling somewhere in resindvdbin.

Jan, where would this best be done?

commit 780d774a5deaca6a87ab3905028fc32a1a2e0087
Author: Sebastian Dröge <>
Date:   Wed Dec 7 13:48:53 2011 +0100

    rsndec: Don't use the initial-identity property on autoconvert
    It was removed, see bug #599469, #665205

commit dcf04269e1eab9d3a015218165f1027b1e4bce51
Author: Sebastian Dröge <>
Date:   Wed Dec 7 13:46:43 2011 +0100

    autoconvert: Remove the initial-identity property from autoconvert
    Initially creating an identity element to forward serialized
    events downstream before any caps are known is broken behaviour.
    Serialized events should only be forwarded downstream if the
    caps are already known, otherwise autopluggers and other elements
    using pad-blocks will fail.
    This behaviour also doesn't work anymore after basetransform
    was fixed to queue serialized events until the caps are known
    as a result of fixing bug #659571.
    See bug #599469, #665205.
Comment 8 Tim-Philipp Müller 2011-12-07 13:04:35 UTC
Also, do you have a test menu for this by any chance, or happen to remember some titles that do?
Comment 9 Jan Schmidt 2011-12-08 00:33:42 UTC
I'm not sure where to insert the event. It might be easiest to put it in a new munge element just before autoconvert, or else to add a 'dummy' pad to the demuxer just for the 'no audio' case.
Comment 10 Stefan Sauer (gstreamer, gtkdoc dev) 2011-12-13 21:46:42 UTC
It seems that "Inglourious Basterds" is one title where it happens. My edition has a menu to pick english/german/turkish and I don't get any menu navigation here. Getting this error.
playsinkconvertbin gstplaysinkconvertbin.c:481:gst_play_sink_convert_bin_cache_converter_caps:<GstPlaySinkAudioConvert@0x1f4f220> No conversion elements

In totem I can select "Go DVD Menu" and that makes it play the DVD (although duration is 0 and I can't seek).
Comment 11 Vincent Penquerc'h 2012-01-19 15:40:42 UTC
I've got a possible patch (attached), which I'm not sure about, because though it fixes the issue (first still frame menu without audio now prerolls, and I can select menu items), I do not get any audio in the second video (the actual video), but I can't tell if that's due to the patch or not because it did not preroll before :)

The patch causes the MPEG demuxer to not create a new pad for the dummy stream, which in turns prevents anything from waiting on that pad where no audio would flow.

After starting the actual movie, there is an actual real audio stream, so a pad is created for the real audio, which should work fine (and it prerolls fine, video plays, but no audio after half a dozen AC3 buffers).

Does anyone who knows what that dummy stream is about know if my patch is correct, and the no-audio-in-movie is unrelated (so a second bug) ?
Comment 12 Vincent Penquerc'h 2012-01-19 15:41:07 UTC
Created attachment 205629 [details] [review]
resdvdsrc: fix preroll wedge when no audio is present
Comment 13 Vincent Penquerc'h 2012-01-19 17:32:56 UTC
Ah, I think I see what's wrong. Not adding a pad on the first movie will cause that pad not to be linked to the audio sink, and that won't be re-done when switching movies.
So the patch cannot work with that system.
Back to reading the code.
Comment 14 Vincent Penquerc'h 2012-01-20 15:36:45 UTC
Created attachment 205704 [details] [review]
resindvd: fix preroll on titles with no audio track
Comment 15 Vincent Penquerc'h 2012-01-20 15:39:36 UTC
Fixed with thaytan's suggestion of adding another munge before the decoder and frobbing the template caps.

Works with my test case (and the audio works fine in the next video).

It's a bit of a hack, but not nearly as bad as I thought I'd end up with.

Hopefully it also works on the other test case mentioned above.

I'll push soonish (plus a few cleanups) unless NAK.
Comment 16 Jan Schmidt 2012-01-21 00:39:36 UTC
Excellent :)

With an audiomunge in place before autoconvert, we might not need the second one at all, but I'd want to test that. It's not much overhead to leave it in place.

The only thing I'd consider changing would be to add the audioconvert in first in rsnaudiodec, and then subtract audio/x-raw-float from the desired_caps - so as to avoid autoplugging any hypothetical 'Decoder' class element that appears in the future and accepts 'audio/x-raw-float' for some strange reason.
Comment 17 Vincent Penquerc'h 2012-01-22 17:37:01 UTC
Created attachment 205823 [details] [review]
resindvd: fix preroll on titles with no audio track
Comment 18 Vincent Penquerc'h 2012-01-22 17:37:59 UTC
Both these changes work for my test case.
New patch attached with those in.
Comment 19 Jan Schmidt 2012-01-22 22:08:23 UTC
Review of attachment 205823 [details] [review]:

looks good
Comment 20 Vincent Penquerc'h 2012-01-23 11:27:46 UTC
Thanks. A few small tidbits are going with it.

commit 1c0ccc45f458a2a3e9dbe49cc2084fbcb3f10267
Author: Vincent Penquerc'h <>
Date:   Fri Jan 20 15:34:27 2012 +0000

    resindvd: fix preroll on titles with no audio track

commit 27eb76bf45112263452b7b47cecd75022d480835
Author: Vincent Penquerc'h <>
Date:   Fri Jan 20 12:25:09 2012 +0000

    rsndvdsrc: fix leak

commit 35c96af778507a44ef800f5b110fd6c7b8433a81
Author: Vincent Penquerc'h <>
Date:   Fri Jan 20 12:15:20 2012 +0000

    resindvdbin: fix video/audio mixup in error message

commit dbad02437c73b4bdb79cac5b8fcc738181db70f0
Author: Vincent Penquerc'h <>
Date:   Fri Jan 20 10:42:21 2012 +0000

    rsnaudiomunge: keep the object ref longer
    Since we do not get a ref to the pad, I'm not certain it's safe
    to drop the object and use the pad later, so hold the object ref
    till we're done with the pad.
Comment 21 Stefan Sauer (gstreamer, gtkdoc dev) 2012-01-23 21:16:00 UTC
GStreamer-CRITICAL **: gst_caps_intersect_full: assertion `GST_IS_CAPS (caps1)' failed

Program received signal SIGTRAP, Trace/breakpoint trap.

Thread 2848242544 (LWP 20295)

  • #0 g_logv
    at gmessages.c line 577
  • #1 g_log
    at gmessages.c line 591
  • #2 g_return_if_fail_warning
  • #3 gst_caps_intersect_full
    at gstcaps.c line 1450
  • #4 gst_caps_intersect
    at gstcaps.c line 1476
  • #5 gst_proxy_pad_getcaps_default
    at gstghostpad.c line 383
  • #6 gst_pad_get_caps_unlocked
    at gstpad.c line 2254
  • #7 gst_pad_get_caps_reffed
    at gstpad.c line 2338
  • #8 gst_pad_peer_get_caps_reffed
    at gstpad.c line 2405
  • #9 getcaps_fold_func
    at gstutils.c line 2814
  • #10 gst_iterator_fold
    at gstiterator.c line 549
  • #11 gst_pad_proxy_getcaps
    at gstutils.c line 2873
  • #12 gst_pad_get_caps_unlocked
    at gstpad.c line 2254
  • #13 gst_pad_get_caps_reffed
    at gstpad.c line 2338
  • #14 gst_pad_get_caps
    at gstpad.c line 2363
  • #15 can_sink_caps
    at resindvdbin.c line 655
  • #16 demux_pad_added
    at resindvdbin.c line 703
  • #17 g_cclosure_marshal_VOID__OBJECT
    at gmarshal.c line 644
  • #18 g_closure_invoke
    at gclosure.c line 774
  • #19 signal_emit_unlocked_R
    at gsignal.c line 3272
  • #20 g_signal_emit_valist
    at gsignal.c line 3003
  • #21 g_signal_emit
    at gsignal.c line 3060
  • #22 gst_element_add_pad
    at gstelement.c line 775
  • #23 gst_flups_demux_get_stream
    at gstmpegdemux.c line 361
  • #24 gst_flups_demux_handle_dvd_event
    at gstmpegdemux.c line 656
  • #25 gst_flups_demux_sink_event
    at gstmpegdemux.c line 927
  • #26 gst_pad_send_event
    at gstpad.c line 5425
  • #27 gst_pad_push_event
    at gstpad.c line 5277
  • #28 rsn_dvdsrc_create
    at resindvdsrc.c line 1348
  • #29 gst_base_src_get_range
    at gstbasesrc.c line 2188

Comment 22 Vincent Penquerc'h 2012-01-23 21:53:14 UTC
Damn, and I'm getting this too somehow. How can I have possibly managed to miss that ? :S
Comment 23 Vincent Penquerc'h 2012-01-23 22:22:58 UTC
Fixed. I had tested it, honest...
Comment 24 Vincent Penquerc'h 2012-01-27 11:14:52 UTC
For ensonic:

Run with rsnaudiomunge:5, and you should see the following message if audiomunge sends the dummy buffer:

  GST_LOG_OBJECT (munge, "Sending %u bytes (%" GST_TIME_FORMAT
      ") of audio data with TS %" GST_TIME_FORMAT,
      buf_size, GST_TIME_ARGS (fill_time), GST_TIME_ARGS (start));