Bug 741783 – qtmux: crash when trying to mux ALAC

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Bug 741783 - qtmux: crash when trying to mux ALAC


Summary:	qtmux: crash when trying to mux ALAC


Status:	RESOLVED FIXED

Product:	GStreamer
Classification:	Platform
Component:	gst-plugins-good
Version:	git master
Hardware:	Other Linux

Importance:	High critical
Target Milestone:	1.5.1
Assigned To:	GStreamer Maintainers
QA Contact:	GStreamer Maintainers

URL:
Whiteboard:

Duplicates:	745619 (view as bug list)
Depends on:
Blocks:

Reported:	2014-12-19 19:47 UTC by Gautier Portet
Modified:	2015-03-04 16:25 UTC

See Also:
GNOME target:	---
GNOME version:	---

Description Gautier Portet 2014-12-19 19:47:08 UTC

I'm trying to encode with ALAC codec, I think the pipeline should be something like "avenc_alac ! mp4mux", but it crashes GStreamer :  

[cerbero-linux-x86_64]:~/cerbero$ gst-launch-1.0 filesrc location=/tmp/blow.flac ! decodebin ! avenc_alac ! mp4mux ! filesink location=/tmp/blow.flac.m4a

Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...

(gst-launch-1.0:211): GStreamer-CRITICAL **: gst_buffer_extract: assertion 'dest != NULL' failed
Caught SIGSEGV
Spinning.  Please run 'gdb gst-launch-1.0 211' to continue debugging, Ctrl-C to quit, or Ctrl-\ to dump core.



I've tested on Ubuntu 14.04, Fedora 21 and git gstreamer, same crash.

Comment 1 Thiago Sousa Santos 2014-12-24 15:49:05 UTC

Thanks for taking the time to report this bug.
Without a stack trace from the crash it's very hard to determine what caused it.
Can you get us a stack trace? Please see http://live.gnome.org/GettingTraces for more information on how to do so. Thanks in advance!

You can also use G_DEBUG=fatal_criticals to get the stack trace at the moment of that assertion

Comment 2 Tim-Philipp Müller 2014-12-25 21:44:14 UTC

Thanks for the bug report. Should be fixed in git master now:

commit aa94fc6beb95ef6b811bec53696403fe47fa1f42
Author: Tim-Philipp Müller <tim@centricular.com>
Date:   Thu Dec 25 21:32:40 2014 +0000

    qtmux: fix ALAC muxing
    
    Actually copy the codec data instead of copying nothing
    and then bombing out because there's no data.
    
    Fixes: gst-launch-1.0 audiotestsrc ! avenc_alac ! qtmux ! fakesink
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741783

Comment 3 Tim-Philipp Müller 2014-12-25 21:46:18 UTC

For the record, here's the stack trace:

0:00:00.471982545  9698 0x7fffec04d0a0 DEBUG                  qtmux gstqtmux.c:2669:gst_qt_mux_audio_sink_set_caps:<mp4mux0> mp4mux0:audio_0, caps=audio/x-alac, channels=(int)2, rate=(int)44100, channel-mask=(bitmask)0x0000000000000003, samplesize=(int)0, codec_data=(buffer)00000024616c616300000000000010000010280a0e02000000004004001588800000ac44

(gst-launch-1.0:9698): GStreamer-CRITICAL **: gst_buffer_extract: assertion 'dest != NULL' failed

Program received signal SIGTRAP, Trace/breakpoint trap.

+ Trace 234453

Thread 140737250060032 (LWP 9704)

#0 g_logv
at gmessages.c line 1046
#1 g_log
at gmessages.c line 1079
#2 g_return_if_fail_warning
at gmessages.c line 1088
#3 gst_buffer_extract
at gstbuffer.c line 1698
#4 atom_data_new_from_gst_buffer
at atoms.c line 213
#5 build_codec_data_extension
at atoms.c line 4537
#6 gst_qt_mux_audio_sink_set_caps
at gstqtmux.c line 2885
#7 gst_qt_mux_sink_event
at gstqtmux.c line 3378



data->data was NULL because the codec_config GstBuffer had a length of 0, so nothing got allocated, and it was 0 because no data was copied because of flags=NONE passed to gst_buffer_copy_region().

Comment 4 Stephane Cerveau 2015-03-04 16:25:24 UTC

*** Bug 745619 has been marked as a duplicate of this bug. ***