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Bug 591172 - Inconsistent transcoding of iTunes AAC files.
Inconsistent transcoding of iTunes AAC files.
Status: RESOLVED OBSOLETE
Product: GStreamer
Classification: Platform
Component: dont know
0.10.23
Other All
: Normal normal
: NONE
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2009-08-08 20:09 UTC by W. Michael Petullo
Modified: 2010-02-23 00:29 UTC
See Also:
GNOME target: ---
GNOME version: ---


Attachments
Test AAC fragment that encodes PROPERLY (200.00 KB, application/octet-stream)
2009-08-08 20:11 UTC, W. Michael Petullo
Details
Test AAC fragment that encodes IMPROPERLY (200.00 KB, application/octet-stream)
2009-08-08 20:13 UTC, W. Michael Petullo
Details
Output from clear transcoding (5.20 KB, text/plain)
2009-08-17 23:21 UTC, W. Michael Petullo
Details
Output from distorted transcoding (5.21 KB, text/plain)
2009-08-17 23:21 UTC, W. Michael Petullo
Details

Description W. Michael Petullo 2009-08-08 20:09:23 UTC
Please describe the problem:
I am trying to use gstreamer to transcode unprotected iTunes AAC files into FLAC. The results are inconsistent.

Steps to reproduce:
gst-launch filesrc location=TEST.m4a ! decodebin ! audioconvert ! flacenc ! filesink location=TEST.flac


Actual results:
Sometimes the resulting FLAC file sounds right. Often, though, the result sounds incorrect, as if the tempo is off.

Expected results:
Consistent audio.

Does this happen every time?
Yes.

Other information:
I am trying to play the resulting files using VLC 0.9.8 on Mac OS X 10.4. I have tried running the GStreamer pipeline on both Mac OS X and Fedora 11. On Mac OS X, I am using the following:
Comment 1 W. Michael Petullo 2009-08-08 20:11:37 UTC
Created attachment 140227 [details]
Test AAC fragment that encodes PROPERLY

This file transcodes properly when using the pipeline noted above.
Comment 2 W. Michael Petullo 2009-08-08 20:13:26 UTC
Created attachment 140228 [details]
Test AAC fragment that encodes IMPROPERLY

This file does not transcode properly when using the pipeline noted above. The resulting FLAC file is severely distorted. Both this and the previous fragment are encoded using the same format and came from the same source.
Comment 3 W. Michael Petullo 2009-08-09 15:32:16 UTC
I've done some more testing and have found:

"faad FOO.m4a" creates FOO.wav and this sounds FINE.

"faad FOO.m4a" followed by "flac FOO.wav" sounds FINE.

But, using GStreamer:

"/opt/local/bin/gst-launch filesrc location=FOO.wav ! decodebin ! audioconvert ! flacenc ! filesink location=FOO.flac" creates a FLAC audio file that is DISTORTED.

Although:

"/opt/local/bin/gst-launch filesrc location=FOO.m4a ! decodebin ! audioconvert ! wavenc ! filesink location=FOO.wav" creates a WAV audio file that sounds FINE.

Comment 4 Sebastian Dröge (slomo) 2009-08-17 16:00:39 UTC
I can't hear a difference between just playing the second AAC file and between transcoding it to FLAC and then playing the resulting FLAC file.

Which versions of gstreamer, gst-plugins-base, gst-plugins-good and FLAC are you using? What's the output if you add "-v" to your transcoding pipeline (for both cases, the distorted FLAC encoding and the non-distorted FLAC encoding).
Comment 5 W. Michael Petullo 2009-08-17 23:21:09 UTC
Created attachment 141006 [details]
Output from clear transcoding
Comment 6 W. Michael Petullo 2009-08-17 23:21:28 UTC
Created attachment 141007 [details]
Output from distorted transcoding
Comment 7 W. Michael Petullo 2009-08-17 23:25:28 UTC
FYI, the distortion I hear is very heavy. You can't miss it. So, I think you did not have my problem when you did your transcode.

I am using the following packages from MacPorts:

gst-plugins-bad                @0.10.12        gnome/gst-plugins-bad
gst-plugins-bad                @0.10.12        gnome/gst-plugins-bad
gst-plugins-base               @0.10.23        gnome/gst-plugins-base
gst-plugins-base               @0.10.23        gnome/gst-plugins-base
gst-plugins-good              @0.10.15        gnome/gst-plugins-good
gstreamer                            @0.10.23        gnome/gstreamer
flac                                        @1.2.1             audio/flac
faac                                       @1.28              audio/faac
faad2                                    @2.6.1             audio/faad2
Comment 8 W. Michael Petullo 2010-02-20 16:18:17 UTC
A recent update has fixed this on both Fedora and Mac OS X 10.6.2. On Mac OS X, I am now using:

gst-plugins-bad                @0.10.17        gnome/gst-plugins-bad
gst-plugins-base               @0.10.25        gnome/gst-plugins-base
gst-plugins-good               @0.10.17        gnome/gst-plugins-good
gst-plugins-ugly               @0.10.13        gnome/gst-plugins-ugly
gstreamer                      @0.10.25        gnome/gstreamer
Comment 9 Tim-Philipp Müller 2010-02-23 00:29:03 UTC
(Marking as obsolete instead, since we don't really know what fixed it where and when)