Reading one channel AAC file using playbin2 returns stereo data

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Reading one channel AAC file using playbin2 returns stereo data

Dinesh Iyer
Hello,
I am using playbin2 to read audio data from AAC and MP3 files. I noticed
that when I attempt to read one channel AAC files, the output returned is
stereo with both channels having the same data. Single channel MP3 and WAV
files were read in as expected. I am attaching an image of the pipeline
obtained when using the following gst-launch command:

gst-launch-0.10 playbin2
uri=file:///local/playbin2_appsink_aac_mono/testWelcomeMono.m4a
audio-sink=appsink video-sink=fakesink text-sink=fakesink



Regards,
Dinesh

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Re: Reading one channel AAC file using playbin2 returns stereo data

michael smith-6-3
As you can see from the image you attached, the input to FAAD says
it's mono  (channels=1), but the output from FAAD has channels=2.

This probably means that it's marked as mono in the container (mp4),
but is actually stereo - faad cares more about the actual AAC contents
than about what the container says, so overrides it.

So this is happening solely inside faad - it's not gstreamer
converting to another format or anything complex like that. I guess
you don't really have a mono AAC file.

Mike


On Wed, Feb 8, 2012 at 9:09 AM, Dinesh Iyer <[hidden email]> wrote:

> Hello,
> I am using playbin2 to read audio data from AAC and MP3 files. I noticed
> that when I attempt to read one channel AAC files, the output returned is
> stereo with both channels having the same data. Single channel MP3 and WAV
> files were read in as expected. I am attaching an image of the pipeline
> obtained when using the following gst-launch command:
>
> gst-launch-0.10 playbin2
> uri=file:///local/playbin2_appsink_aac_mono/testWelcomeMono.m4a
> audio-sink=appsink video-sink=fakesink text-sink=fakesink
>
>
>
> Regards,
> Dinesh
>
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
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Re: Reading one channel AAC file using playbin2 returns stereo data

Dinesh Iyer
Hi Mike,
Thanks for your reply. I created this file using Media Foundation on Windows. When I read the same file on Windows and Mac, it identifies the audio stream to have only 1 channel. Could this be a bug with Faad?

Regards,
Dinesh

On Wed, Feb 8, 2012 at 1:40 PM, Michael Smith <[hidden email]> wrote:
As you can see from the image you attached, the input to FAAD says
it's mono  (channels=1), but the output from FAAD has channels=2.

This probably means that it's marked as mono in the container (mp4),
but is actually stereo - faad cares more about the actual AAC contents
than about what the container says, so overrides it.

So this is happening solely inside faad - it's not gstreamer
converting to another format or anything complex like that. I guess
you don't really have a mono AAC file.

Mike


On Wed, Feb 8, 2012 at 9:09 AM, Dinesh Iyer <[hidden email]> wrote:
> Hello,
> I am using playbin2 to read audio data from AAC and MP3 files. I noticed
> that when I attempt to read one channel AAC files, the output returned is
> stereo with both channels having the same data. Single channel MP3 and WAV
> files were read in as expected. I am attaching an image of the pipeline
> obtained when using the following gst-launch command:
>
> gst-launch-0.10 playbin2
> uri=file:///local/playbin2_appsink_aac_mono/testWelcomeMono.m4a
> audio-sink=appsink video-sink=fakesink text-sink=fakesink
>
>
>
> Regards,
> Dinesh
>
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
_______________________________________________
gstreamer-devel mailing list
[hidden email]
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Re: Reading one channel AAC file using playbin2 returns stereo data

Stefan Sauer
In reply to this post by Dinesh Iyer
On 02/08/2012 06:09 PM, Dinesh Iyer wrote:
Hello,
I am using playbin2 to read audio data from AAC and MP3 files. I noticed
that when I attempt to read one channel AAC files, the output returned is
stereo with both channels having the same data. Single channel MP3 and WAV
files were read in as expected. I am attaching an image of the pipeline
obtained when using the following gst-launch command:

gst-launch-0.10 playbin2
uri=file:///local/playbin2_appsink_aac_mono/testWelcomeMono.m4a
audio-sink=appsink video-sink=fakesink text-sink=fakesink


Sounds like a bug in faad (either in the gstreamer plugin or in the library). Please file a bug.

Stefan
Regards,
Dinesh
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