PyBindGen

How would you wrap a complicated C struct (pointers to functions, ** pointers)?

Asked by Billy Chang

Hi, I'm quite new to PyBindGen, and maybe I'm crazy but I'm trying to wrap parts of ffmpeg.
There are a few quite complicated structs which I'm not certain how to wrap:

typedef struct AVOutputFormat {
    const char *name;

    enum CodecID audio_codec;

    int (*write_header)(struct AVFormatContext *);
    int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);

    int (*set_parameters)(struct AVFormatContext *, AVFormatParameters *);
    int (*interleave_packet)(struct AVFormatContext *, AVPacket *out, AVPacket *in, int flush);

    const struct AVCodecTag **codec_tag;

    /* private fields */
    struct AVOutputFormat *next;
} AVOutputFormat;

How would you wrap this struct?

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Gustavo Carneiro (gjc) said : 		#1

Erm.. I don't think you can wrap most of it with pybindgen, or at least not automatically, sorry :P

First you start with wrapping the structure:
 AVOutputFormat = module.add_struct('AVOutputFormat')

Then you add the fields:

  AVOutputFormat.add_instance_attribute('name', retval('char*', 'name', is_const=True))
  AVOutputFormat.add_instance_attribute('audio_codec', retval('CodecID', 'audio_codec'))

The rest are function pointers, and ** pointers to structs (array?), which are not directly supported by pybindgen.

If it was me, I would simply code the AVOutputFormat python type manually and integrate it with pybindgen through type handlers.

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