[FFmpeg-devel] [PATCH] Add asrc_anullsrc - null audio source

[Michael Niedermayer]

On Wed, Sep 15, 2010 at 12:56:38AM +0200, Stefano Sabatini wrote:
> On date Monday 2010-08-23 23:45:39 +0200, Stefano Sabatini encoded:
> > On date Monday 2010-08-23 13:35:32 -0700, S.N. Hemanth Meenakshisundaram encoded:
> > > > On date Monday 2010-08-23 20:24:10 +0200, Michael Niedermayer encoded:
> > > >> On Sat, Aug 21, 2010 at 12:25:24AM +0200, Stefano Sabatini wrote:
> > > >> > On date Friday 2010-08-20 01:06:04 +0200, Michael Niedermayer encoded:
> > > >> > > On Fri, Aug 20, 2010 at 01:03:27AM +0200, Stefano Sabatini wrote:
> > > >> > [...]
> > > >> > > > > > +    priv->channel_layout = CH_LAYOUT_STEREO;
> > > >> > > > > > +
> > > >> > > > > > +    if (args)
> > > >> > > > > > +        sscanf(args, "%ld:%ld", &priv->sample_rate,
> > > >> &priv->channel_layout);
> > > >> > > > >
> > > >> > > > > reading channel layout like this is maybe not ideal
> > > >> > > >
> > > >> > > > Please elaborate.
> > > >> > >
> > > >> > > 7
> > > >> > >
> > > >> > > you want an english awnser instead of a number?
> > > >> > > the user also wants to specify his speaker configuration be listing
> > > >> > > speakers and not just their number
> > > >> >
> > > >> > I suppose this means that the user should be able to specify a string
> > > >> > rather than a number? I had the same concern, but I'm not sure we have
> > > >> > an API right now for doing the string <-> number mapping.
> > > >>
> > > >> yes
> > > >> but not only that, x channels is ambigous, there can be several layouts
> > > >> with x channels
> > > >
> > > > OK now I see, channel_layout contains flags, these the values:
> > > > #define CH_FRONT_LEFT             0x00000001
> > > > #define CH_FRONT_RIGHT            0x00000002
> > > > #define CH_FRONT_CENTER           0x00000004
> > > > #define CH_LOW_FREQUENCY          0x00000008
> > > > #define CH_BACK_LEFT              0x00000010
> > > > #define CH_BACK_RIGHT             0x00000020
> > > > #define CH_FRONT_LEFT_OF_CENTER   0x00000040
> > > > #define CH_FRONT_RIGHT_OF_CENTER  0x00000080
> > > > #define CH_BACK_CENTER            0x00000100
> > > > #define CH_SIDE_LEFT              0x00000200
> > > > #define CH_SIDE_RIGHT             0x00000400
> > > > #define CH_TOP_CENTER             0x00000800
> > > > #define CH_TOP_FRONT_LEFT         0x00001000
> > > > #define CH_TOP_FRONT_CENTER       0x00002000
> > > > #define CH_TOP_FRONT_RIGHT        0x00004000
> > > > #define CH_TOP_BACK_LEFT          0x00008000
> > > > #define CH_TOP_BACK_CENTER        0x00010000
> > > > #define CH_TOP_BACK_RIGHT         0x00020000
> > > > #define CH_STEREO_LEFT            0x20000000  ///< Stereo downmix.
> > > > #define CH_STEREO_RIGHT           0x40000000  ///< See CH_STEREO_LEFT.
> > > >
> > > > Since they are so much, I'd prefer to keep it as an integer, then when
> > > > we will have an options API for doing flags <-> string conversion that
> > > > may be used instead.
> > > >
> > > 
> > > There is already a flags to string mapping in libavcodec/audioconvert.c,
> > > is there a problem with using those?
> > > I had posted a patch for converting these strings to flags a couple of
> > > days ago.
> > 
> > After reading again the avcodec_get_channel_layout_string(), yes that
> > should be fine.
> > 
> > > Also, the code above currently reads in the channel layout flag and not
> > > the number of channels, since number of channels map to more than one
> > > layout.
> 
> Ping.

as said, the filter must be functional to be approved.
source implicates that it produces some samples, a filter never returning a
single sample is just broken.
and you dont need a mixer (whatever that may be) to return an array inited
with memset(0)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Avoid a single point of failure, be that a person or equipment.
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