Quiet output from playbin on maemo

[Jeffrey Barish]

I have been using playbin to output ogg files on Linux and Windows
platforms.  Recently, I tried moving the code to maemo (Nokia N800).  I get
an output, but it's very quiet.  When I multiply the playbin volume
parameter by 8, the volume is about normal, but then the signal is
distorted.  Is there another parameter that could be affecting loudness
(e.g., pan)?  Where can I find a list of parameters?  Is there some other
way to account for the problem?  Does anyone happen to know of an N800
application that uses playbin?  Other applications I have tested on the
platform (e.g., Media player) do produce an output at a normal loudness.
--
Jeffrey Barish


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[Stefan Sauer]

hi,

Jeffrey Barish schrieb:

> I have been using playbin to output ogg files on Linux and Windows
> platforms.  Recently, I tried moving the code to maemo (Nokia N800).  I get
> an output, but it's very quiet.  When I multiply the playbin volume
> parameter by 8, the volume is about normal, but then the signal is
> distorted.  Is there another parameter that could be affecting loudness
> (e.g., pan)?  Where can I find a list of parameters?  Is there some other
> way to account for the problem?  Does anyone happen to know of an N800
> application that uses playbin?  Other applications I have tested on the
> platform (e.g., Media player) do produce an output at a normal loudness.
>  

that would indicate that the alsasink/dsppcmsink volume is too low. Its
not in the gstreamer side og things. I would recommend to check on
maemo-devel list too to se if someone has already found out.

Stefan

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[Kalle Vahlman]

2008/6/5 Stefan Kost <[hidden email]>:

> hi,
>
> Jeffrey Barish schrieb:
>> I have been using playbin to output ogg files on Linux and Windows
>> platforms.  Recently, I tried moving the code to maemo (Nokia N800).  I get
>> an output, but it's very quiet.  When I multiply the playbin volume
>> parameter by 8, the volume is about normal, but then the signal is
>> distorted.  Is there another parameter that could be affecting loudness
>> (e.g., pan)?  Where can I find a list of parameters?  Is there some other
>> way to account for the problem?  Does anyone happen to know of an N800
>> application that uses playbin?  Other applications I have tested on the
>> platform (e.g., Media player) do produce an output at a normal loudness.
>>
> that would indicate that the alsasink/dsppcmsink volume is too low. Its
> not in the gstreamer side og things. I would recommend to check on
> maemo-devel list too to se if someone has already found out.

We had this problem in kilikali and fixed it with the following code
(not sure if it's valid but it's based on empirical testing and
results and seems to work so...):

#ifdef MAEMO_CHANGES
  /* Ok, here are the rules that seem to be in effect:
  *  - standard playbin really only has the range 0.0...1.0 since anything
  *    over 1.0 starts to distort the sound
  *  - maemo playbin seems to set the volume element volume to 0.0, dunno why
  *  - maemo playbin uses the whole 0.0...10.0 range to control the dsp sink
  *
  * So in principle you could adjust volume the same way everywhere but
  * you just won't like the result (1/10th of max volume) on maemo.
  *
  * So we hack around, as usual.
  */
  g_object_set (G_OBJECT(self->audiobin), "volume",
                (gdouble)(1.0*volume/10.0), NULL);

  {
    GstElement *sink = gst_bin_get_by_name(GST_BIN(self->audiobin), "volume");
    if (sink != NULL)
    {
      g_object_set (G_OBJECT(sink), "volume", 1.0, NULL);
    }
  }
#else
  g_object_set (G_OBJECT(self->audiobin), "volume",
                self->priv->volume, NULL);
#endif

The dsp sinks I believe have their own volume setting so the funky
behaviour might be caused by that but I don't know.

--
Kalle Vahlman, [hidden email]
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[Jeffrey Barish]

Kalle Vahlman wrote:

> We had this problem in kilikali and fixed it with the following code
> (not sure if it's valid but it's based on empirical testing and
> results and seems to work so...):
>
> #ifdef MAEMO_CHANGES
>   /* Ok, here are the rules that seem to be in effect:
>   *  - standard playbin really only has the range 0.0...1.0 since anything
>   *    over 1.0 starts to distort the sound
>   *  - maemo playbin seems to set the volume element volume to 0.0, dunno
>   why
>   *  - maemo playbin uses the whole 0.0...10.0 range to control the dsp
>   sink *
>   * So in principle you could adjust volume the same way everywhere but
>   * you just won't like the result (1/10th of max volume) on maemo.
>   *
>   * So we hack around, as usual.
>   */
>   g_object_set (G_OBJECT(self->audiobin), "volume",
>                 (gdouble)(1.0*volume/10.0), NULL);
>
>   {
>     GstElement *sink = gst_bin_get_by_name(GST_BIN(self->audiobin),
>     "volume"); if (sink != NULL)
>     {
>       g_object_set (G_OBJECT(sink), "volume", 1.0, NULL);
>     }
>   }
> #else
>   g_object_set (G_OBJECT(self->audiobin), "volume",
>                 self->priv->volume, NULL);
> #endif
>
> The dsp sinks I believe have their own volume setting so the funky
> behaviour might be caused by that but I don't know.

This code looks interesting, but I'm not getting it -- in part, perhaps,
because I am actually coding in Python.

1. If we're not on maemo, then we're in the else clause.  You say that
playbin really only has the range of 0.0 - 1.0, so I presume that
self->priv->volume has the range 0.0 - 1.0.  In the maemo case, you say
that the playbin uses the range 0.0 - 10.0.  The volume variable presumably
refers to something different from self->priv->volume, but it's hard to
imagine why you would have to divide it by 10.0 rather than multiplying it
by 10.0.  In any case, I had already tried multiplying by 8.0 (I just
picked a number out of a hat) and found that the sound was distorted.  To
be precise, I created a playbin with

player = gst.element_factory_make('playbin', 'player')

and then set its volume with

player.set_property('volume', 8.0 * v)

The sound does get louder, but it's distorted.

2. I don't know GStreamer well enough to fully understand what you're doing
in the gst_bin_get_by_name.  I tried

player.get_by_name('volume')

but got None.  I assume that this code addresses your second bullet item:
playbin sets the volume element volume to 0.0 so you are setting it to 1.0.
So there is a volume element volume that is different from the playbin
volume?  If it really is a separate volume control, why am I getting any
output if its value is set to 0 by default?
--
Jeffrey Barish


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