On Mon, Apr 06, 2020 at 09:23:26AM +0530, Gautam Ramakrishnan wrote:
> On Mon, Apr 6, 2020 at 1:16 AM Michael Niedermayer
> <mich...@niedermayer.cc> wrote:
> >
> > On Sun, Apr 05, 2020 at 04:13:28PM +0530, gautamr...@gmail.com wrote:
> > > From: Gautam Ramakrishnan <gautamr...@gmail.com>
> > >
> > > This patch adds functional changes to support the
> > > PPT marker. This patch fixes bug ticket #4610.
> > > ---
> > > libavcodec/jpeg2000dec.c | 88 +++++++++++++++++++++++++++++++++++-----
> > > 1 file changed, 77 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
> > > index 732d88e6fc..2af3c61c37 100644
> > > --- a/libavcodec/jpeg2000dec.c
> > > +++ b/libavcodec/jpeg2000dec.c
> > > @@ -83,6 +83,10 @@ typedef struct Jpeg2000Tile {
> > > Jpeg2000QuantStyle qntsty[4];
> > > Jpeg2000POC poc;
> > > Jpeg2000TilePart tile_part[32];
> > > + uint8_t has_ppt; // whether this tile has
> > > a ppt marker
> > > + uint8_t *packed_headers; // contains packed
> > > headers. Used only along with PPT marker
> > > + int packed_headers_size; // size in bytes of the
> > > packed headers
> > > + GetByteContext packed_headers_stream; // byte context
> > > corresponding to packed headers
> > > uint16_t tp_idx; // Tile-part index
> > > int coord[2][2]; // border coordinates {{x0, x1},
> > > {y0, y1}}
> > > } Jpeg2000Tile;
> > > @@ -855,6 +859,37 @@ static int get_plt(Jpeg2000DecoderContext *s, int n)
> > > return 0;
> > > }
> > >
> > > +static int get_ppt(Jpeg2000DecoderContext *s, int n)
> > > +{
> > > + Jpeg2000Tile *tile;
> > > +
> > > + if (s->curtileno < 0)
> > > + return AVERROR_INVALIDDATA;
> > > +
> > > + tile = &s->tile[s->curtileno];
> > > + if (tile->tp_idx != 0) {
> > > + av_log(s->avctx, AV_LOG_ERROR,
> > > + "PPT marker can occur only on first tile part of a
> > > tile.\n");
> > > + return AVERROR_INVALIDDATA;
> > > + }
> > > +
> > > + tile->has_ppt = 1; // this tile has a ppt marker
> > > + bytestream2_get_byte(&s->g); // Zppt is skipped and not used
> >
> >
> > > + if (!tile->packed_headers)
> > > + tile->packed_headers = av_malloc(n - 3);
> > > + else
> > > + tile->packed_headers = av_realloc(tile->packed_headers,
> > > + tile->packed_headers_size + n
> > > - 3);
> >
> > why is the special case with av_malloc() needed ?
> >
> The if else is to check whether this is the first time this tile is being
> allocated its packed headers. If packed headers does not exist
> exist, create it. The else condition is just to add a new packed
> header to it.what is the problem with av_realloc(tile->packed_headers, tile->packed_headers_size + n - 3); when tile->packed_headers is NULL and tile->packed_headers_size is 0 for the first allocation ? thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB In fact, the RIAA has been known to suggest that students drop out of college or go to community college in order to be able to afford settlements. -- The RIAA
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