[FFmpeg-devel] [RFC] WC3 decoder without AVPaletteControl

[Michael Niedermayer]

On Sun, Apr 12, 2009 at 01:26:33PM +0200, Reimar D?ffinger wrote:
> On Sun, Apr 12, 2009 at 12:19:07AM +0200, Reimar D?ffinger wrote:
> > attached patch implements this.
> > It is a bit ugly because it adds a lot of seeking to the demuxer, but I
> > think for such a fringe format there is no point in extra work for avoiding it.
> > The patch also adds two helper functions, one to increase the size of a
> > packet and one that appends data read from a file to a possibly already
> > filled packet.
> > I expect that there will be more that a few bugs still, e.g. while the
> > video looks visually ok in ffplay the FATE regressions do not match at
> > all.
> 
> A minor update. It only fixes the gamma correction and provides a
> fixed point integer-implementation, which might help explain some of
> its weirdness like clipping to 253.

[...]
> Index: libavcodec/avcodec.h
> ===================================================================
> --- libavcodec/avcodec.h	(revision 18467)
> +++ libavcodec/avcodec.h	(working copy)
> @@ -2666,6 +2666,14 @@
>  void av_shrink_packet(AVPacket *pkt, int size);
>  
>  /**
> + * Increase packet size, correctly zeroing padding
> + *
> + * @param pkt packet
> + * @param grow_by number of bytes by which to increase the size of the packet
> + */
> +int av_grow_packet(AVPacket *pkt, int grow_by);
> +
> +/**
>   * @warning This is a hack - the packet memory allocation stuff is broken. The
>   * packet is allocated if it was not really allocated.
>   */
> Index: libavcodec/avpacket.c
> ===================================================================
> --- libavcodec/avpacket.c	(revision 18467)
> +++ libavcodec/avpacket.c	(working copy)
> @@ -69,6 +69,24 @@
>      memset(pkt->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
>  }
>  
> +int av_grow_packet(AVPacket *pkt, int grow_by)
> +{
> +    void *new_ptr;

> +    if (!grow_by)
> +        return 0;

for what is that good for?


> +    if (!pkt->size)
> +        return av_new_packet(pkt, grow_by);

> +    if (pkt->size + FF_INPUT_BUFFER_PADDING_SIZE > INT_MAX - grow_by)
> +        return -1;

could you write this in a way that is free of overflows please ;)


[...]
> Index: libavformat/utils.c
> ===================================================================
> --- libavformat/utils.c	(revision 18467)
> +++ libavformat/utils.c	(working copy)
> @@ -277,6 +277,20 @@
>      return ret;
>  }
>  
> +int av_append_packet(ByteIOContext *s, AVPacket *pkt, int size)
> +{
> +    int ret;
> +    int old_size;
> +    if (!pkt->size)
> +        return av_get_packet(s, pkt, size);
> +    old_size = pkt->size;
> +    ret = av_grow_packet(pkt, size);

isnt av_grow_packet already checking for pkt->size==0 ?

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

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20090415/7b411829/attachment.pgp>