[FFmpeg-soc] [PATCH] lavfi audio framework

Michael Niedermayer michaelni at gmx.at
Wed Aug 4 16:48:12 CEST 2010


On Mon, Aug 02, 2010 at 12:24:36PM +0200, Stefano Sabatini wrote:
> On date Monday 2010-08-02 01:57:57 -0700, S.N. Hemanth Meenakshisundaram encoded:
> > lavfi audio fw using the generalized AVFilterBufferRef struct. Anonymous
> > unions weren't allowed so I had to give the unions some names. Please
> > review and comment.
> > 
> > ---
> >  ffmpeg.c                     |    6 +-
> >  ffplay.c                     |   12 ++--
> >  libavfilter/avfilter.c       |   59 +++++++++++++++++++++-
> >  libavfilter/avfilter.h       |  115 +++++++++++++++++++++++++++++++++++-------
> >  libavfilter/defaults.c       |  105 ++++++++++++++++++++++++++++++++++++--
> >  libavfilter/formats.c        |    3 +-
> >  libavfilter/vf_aspect.c      |    2 +-
> >  libavfilter/vf_crop.c        |    4 +-
> >  libavfilter/vf_drawbox.c     |    6 +-
> >  libavfilter/vf_fifo.c        |    2 +-
> >  libavfilter/vf_fps.c         |    2 +-
> >  libavfilter/vf_hflip.c       |    2 +-
> >  libavfilter/vf_overlay.c     |    8 ++--
> >  libavfilter/vf_pad.c         |    2 +-
> >  libavfilter/vf_pixdesctest.c |    2 +-
> >  libavfilter/vf_rotate.c      |   12 ++--
> >  libavfilter/vf_scale.c       |    6 +-
> >  libavfilter/vf_transpose.c   |   18 +++---
> >  libavfilter/vsrc_buffer.c    |    8 ++--
> >  19 files changed, 302 insertions(+), 72 deletions(-)
> 
> [...]
> > diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
> > index 96fca21..c433c6c 100644
> > --- a/libavfilter/avfilter.h
> > +++ b/libavfilter/avfilter.h
> > @@ -99,21 +99,38 @@ typedef struct AVFilterBuffer
> >  typedef struct AVFilterBufferRef
> >  {
> >      AVFilterBuffer *buf;        ///< the buffer that this is a reference to
> > -    uint8_t *data[4];           ///< picture data for each plane
> > -    int linesize[4];            ///< number of bytes per line
> > -    int w;                      ///< image width
> > -    int h;                      ///< image height
> > +    uint8_t *data[8];           ///< picture/audio data for each plane/channel
> > +    int linesize[8];            ///< number of bytes per line
> >      int format;                 ///< media format
> > +    int perms;                  ///< permissions, see the AV_PERM_* flags
> >  
> >      int64_t pts;                ///< presentation timestamp in units of 1/AV_TIME_BASE
> >      int64_t pos;                ///< byte position in stream, -1 if unknown
> >  
> > -    AVRational pixel_aspect;    ///< pixel aspect ratio
> > -
> > -    int perms;                  ///< permissions, see the AV_PERM_* flags
> > +    union {
> > +        AVRational pixel_aspect; ///< pixel aspect ratio of video buffer
> > +        int64_t channel_layout;  ///< channel layout of audio buffer
> > +    } desc;
> > +
> > +    union {
> > +        int w;                   ///< image width
> > +        int samples_nb;          ///< number of audio samples
> > +    } dim1;
> > +    union {
> > +        int h;                   ///< image height
> > +        int size;                ///< audio buffer size
> > +    } dim2;
> > +
> > +    union {
> > +        int interlaced;          ///< is video frame interlaced
> > +        uint32_t sample_rate;    ///< audio buffer sample rate
> > +    } prop;
> > +
> > +    union {
> > +        int top_field_first;     ///< video field order
> > +        int planar;              ///< audio buffer - planar or packed
> > +    } packing;
> >  
> > -    int interlaced;             ///< is frame interlaced
> > -    int top_field_first;
> >  } AVFilterBufferRef;
> 
> My idea was:
> 
> typedef struct AVFilterBufferRefAudioProps {
>     enum SampleFormat format;
>     int size;
>     int samples_nb;          ///< number of audio samples
>     int planar;              ///< audio buffer - planar or packed
>     int64_t channel_layout;  ///< channel layout of audio buffer
> } AVFilterBufferRefAudioProps;
> 
> typedef struct AVFilterBufferRefVideoProps {
>     enum PixelFormat format;
>     AVRational pixel_aspect; ///< pixel aspect ratio of video buffer
>     int w, h;
>     int interlaced;          ///< is video frame interlaced
>     int top_field_first;     ///< video field order
> } AVFilterBufferRefVideoProps;
> 
> typedef struct AVFilterBufferRef {
>     AVFilterBuffer *buf;        ///< the buffer that this is a reference to
>     uint8_t *data[8];           ///< picture/audio data for each plane/channel
>     int linesize[8];            ///< number of bytes per line
>     enum AVMediaType type;   
> 
>     int format;                 ///< media format, this can be eventually moved to the media props
>     int perms;                  ///< permissions, see the AV_PERM_* flags
>   
>     int64_t pts;                ///< presentation timestamp in units of 1/AV_TIME_BASE
>     int64_t pos;                ///< byte position in stream, -1 if unknown
> 
>     union {
>         AVFilterBufferRefAudioProps audio;
>         AVFilterBufferRefVideoProps video;
>     } props;
> } AVFilterBufferRef;
> 
> wxhere the semantics is:
> "A filter buffer has a reference which has a media type and contains
> some properties, which depends on the media type of the reference."
> 
> alternatively you may allocate the media props and reference them from
> the AVFilterBufferRef through a void pointer:
> 
> void *props;  ///< media props, cast it to the right type
> 
> e.g.:
> 
> AVFilterBuffereRef *ref;
> assert(ref->type == AVMEDIA_TYPE_AUDIO);
> AVFilterBuffereRefAudioProps *props = ref->props;
> 
> This would be more robust (no ABI breaks at each media props field
> addition), but may be potentially slower.

yes we need a pointer, the ABI issues would be too annoying


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

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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