[FFmpeg-devel] [PATCH] Per-frame metadata

[Michael Niedermayer]

On Mon, Apr 11, 2011 at 04:59:36PM +0200, Nicolas George wrote:
> Hi.
> 
> The attached series of patches introduce per-frame metadata, and in
> particular PNG zTXt and tEXt chunks decoding.
> 
> I did not try to make it work for CC subtitles, as I do not know what
> exactly would be required, but I believe this is a first step in that
> direction too.
> 
> Regards,
> 
> -- 
>   Nicolas George

>  mem.c |   15 +++++++++++++++
>  mem.h |   25 +++++++++++++++++++++++++
>  2 files changed, 40 insertions(+)
> 26e27b9331a3a098f132399fbe129cc44e561219  0001-Introduce-av_size_mult-and-av_realloc_f.patch
> From c0557275f39dc7bc8049fa04cb0347e065147152 Mon Sep 17 00:00:00 2001
> From: Nicolas George <nicolas.george at normalesup.org>
> Date: Sun, 20 Mar 2011 19:39:20 +0100
> Subject: [PATCH 1/5] Introduce av_size_mult and av_realloc_f.
> 
> av_size_mult helps checking for overflow when computing the size of a memory
> area.
> 
> av_realloc_f helps avoiding memory-leaks in typical uses of realloc.
> 
> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
> ---
>  libavutil/mem.c |   15 +++++++++++++++
>  libavutil/mem.h |   25 +++++++++++++++++++++++++
>  2 files changed, 40 insertions(+), 0 deletions(-)
> 
> diff --git a/libavutil/mem.c b/libavutil/mem.c
> index 7ffd6cb..26fb8c6 100644
> --- a/libavutil/mem.c
> +++ b/libavutil/mem.c
> @@ -136,6 +136,21 @@ void *av_realloc(void *ptr, FF_INTERNAL_MEM_TYPE size)
>  #endif
>  }
>  
> +void *av_realloc_f(void *ptr, size_t nelem, size_t elsize)

what does the _f stand for?



[...]
> @@ -131,4 +141,19 @@ char *av_strdup(const char *s) av_malloc_attrib;
>   */
>  void av_freep(void *ptr);
>  
> +/**
> + * Multiplies two size_t values checking for overflow.
> + * @return  0 if success, -1 if overflow.
> + */
> +static inline int av_size_mult(size_t a, size_t b, size_t *r)
> +{
> +    size_t t = a * b;
> +    /* Hack inspired from glibc: only try the division if nelem and elsize
> +     * are both greater than sqrt(SIZE_MAX). */
> +    if ((a | b) >= ((size_t)1 << (sizeof(size_t) * 4)) && a && t / a != b)
> +        return -1;
> +    *r = t;
> +    return 0;
> +}
> +
>  #endif /* AVUTIL_MEM_H */

LGTM


[...]

> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index 3fa012d..65b7d7f 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -390,6 +390,7 @@ void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic){
>  //        pic->base[i]=NULL;
>      }
>  //printf("R%X\n", pic->opaque);
> +    av_metadata_free(&pic->metadata);
>  
>      if(s->debug&FF_DEBUG_BUFFERS)
>          av_log(s, AV_LOG_DEBUG, "default_release_buffer called on pic %p, %d buffers used\n", pic, s->internal_buffer_count);

That looks like it will cause a leak in applications using their own
release_buffer()


[...]

-- 
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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