[FFmpeg-devel] [PATCH] lavc/avcodec.h: document bitstream filter API

[Michael Niedermayer]

On Thu, Jul 04, 2013 at 07:35:31PM +0200, Stefano Sabatini wrote:
> On date Friday 2013-06-28 17:06:42 -0800, Lou Logan encoded:
> > This is only a review of the language.
> > 
> > On Wed, 26 Jun 2013 19:01:19 +0200, Stefano Sabatini wrote:
> > 
> > > ---
> > >  libavcodec/avcodec.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 49 insertions(+)
> [...]  
> > > +/**
> > > + * If f is NULL, return the first registered bitstream filter,
> > > + * if f is non-NULL, return the next registered bitstream filter
> > > + * after f, or NULL if f is the last one.
> > 
> > Excuse my ignorance, but what does "one" refer to?
> 
> The last registered bitstream filter (text copied and edited from the
> other corresponding doxies).
> 
> Updated with a more detailed discussion of the filter() return codes.
> -- 
> FFmpeg = Fascinating and Fancy Merciful Peaceless Enchanting Gorilla

>  avcodec.h |   62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 698259d9a72425f995dbcc275c503a61437f5294  0003-lavc-avcodec.h-document-bitstream-filter-API.patch
> From da825e46e9cf9f9c644970d89433b8e32857ef99 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Wed, 26 Jun 2013 18:57:09 +0200
> Subject: [PATCH] lavc/avcodec.h: document bitstream filter API
> 
> ---
>  libavcodec/avcodec.h | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 3f3352f..7568e1d 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -4620,14 +4620,76 @@ typedef struct AVBitStreamFilter {
>      struct AVBitStreamFilter *next;
>  } AVBitStreamFilter;
>  
> +/**
> + * Register the bitstream filter bsf.

i would avoid refering to the variable name from the prototype here in
the first line

What does the function do?
Register a bitstream filter



> + *
> + * The filter will be accessible to the application code through
> + * av_bitstream_filter_next() or can be directly initialized with
> + * av_bitstream_filter_init().
> + *
> + * @see avcodec_register_all()
> + */
>  void av_register_bitstream_filter(AVBitStreamFilter *bsf);
> +

> +/**
> + * Create and initialize a bitstream filter context given a bitstream
> + * filter name.
> + *
> + * The returned context must be freed with av_bitstream_filter_close().
> + *
> + * @param name    the name of the bitstream filter
> + * @return a bitstream context if a corresponding filter was found and
> + * successfully initialized, NULL otherwise.

"a bitstream context" ?


> + */
>  AVBitStreamFilterContext *av_bitstream_filter_init(const char *name);
> +
> +/**
> + * Filter bitstream.
> + *
> + * This function filters the buffer buf with size buf_size, and places the
> + * filtered buffer in the buffer pointed to by poutbuf.
> + *
> + * The output buffer must be freed by the caller.
> + *
> + * @param bsfc            bitstream filter context created by av_bitstream_filter_init()
> + * @param avctx           AVCodecContext accessed by the filter, may be NULL.
> + *                        This must be the context of the encoder of the output stream
> + *                        the packet is sent to.
> + * @param args            arguments which specify the filter configuration
> + * @param poutbuf         pointer which is updated to point to the filtered buffer
> + * @param poutbuf_size    pointer which is updated to the filtered buffer size in bytes
> + * @param buf             buffer containing the data to filter
> + * @param buf_size        size in bytes of buf
> + * @param keyframe        set to non-zero if the buffer to filter corresponds to a key-frame packet data

> + * @return >= 0 in case of success, or a negative code in case of failure.

negaive error code


> + *
> + * If the return value is positive, an output buffer is allocated
> + * *poutbuf, and is distinct from the input buffer.
> + *
> + * In case the return value is 0, the output output buffer is not
> + * allocated, the output buffer should be considered identical to the
> + * input buffer or in case *poutbuf was set it points to the input
> + * buffer (not necessarily to the starting address).
> + */
>  int av_bitstream_filter_filter(AVBitStreamFilterContext *bsfc,
>                                 AVCodecContext *avctx, const char *args,
>                                 uint8_t **poutbuf, int *poutbuf_size,
>                                 const uint8_t *buf, int buf_size, int keyframe);
> +
> +/**
> + * Release bitstream filter context bsf, which was created with
> + * av_bitstream_filter_init().
> + *
> + * @param bsf the bitstream filter context created with
> + * av_bitstream_filter_init(), can be NULL
> + */
>  void av_bitstream_filter_close(AVBitStreamFilterContext *bsf);
>  

> +/**
> + * If f is NULL, return the first registered bitstream filter,
> + * if f is non-NULL, return the next registered bitstream filter
> + * after f, or NULL if f is the last one.

Can be used to iterate over all registered bitstream filters
[example here maybe]

[...]

no more comments from me

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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