[FFmpeg-devel] [PATCH v6 1/2] libavcodec/jpeg2000dec.c: Add functions and modify structs for PPT marker support

[Gautam Ramakrishnan]

On Mon, Mar 30, 2020 at 6:31 AM Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> On Sat, Mar 28, 2020 at 09:16:40PM +0530, gautamramk at gmail.com wrote:
> > From: Gautam Ramakrishnan <gautamramk at gmail.com>
> >
> > This patch adds support for the PPT marker. It breaks down the
> > jpeg2000_decode_packet() function to decode headers and data
> > separately.
> > ---
> >  libavcodec/jpeg2000dec.c | 202 +++++++++++++++++++++++++++++++++------
> >  1 file changed, 172 insertions(+), 30 deletions(-)
> >
>
> [...]
>
> > @@ -927,30 +965,38 @@ static int getlblockinc(Jpeg2000DecoderContext *s)
> >      return res;
> >  }
> >
> > -static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile, int *tp_index,
> > -                                  Jpeg2000CodingStyle *codsty,
> > -                                  Jpeg2000ResLevel *rlevel, int precno,
> > -                                  int layno, uint8_t *expn, int numgbits)
> > +static int jpeg2000_decode_packet_header(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
> > +                                         int *tp_index,
> > +                                         Jpeg2000CodingStyle *codsty,
> > +                                         Jpeg2000ResLevel *rlevel, int precno,
> > +                                         int layno, uint8_t *expn, int numgbits,
> > +                                         int *process_data)
> >  {
> >      int bandno, cblkno, ret, nb_code_blocks;
> > -    int cwsno;
> >
> > -    if (layno < rlevel->band[0].prec[precno].decoded_layers)
> > +    if (layno < rlevel->band[0].prec[precno].decoded_layers) {
> > +        *process_data = 0;
> >          return 0;
> > +    }
> >      rlevel->band[0].prec[precno].decoded_layers = layno + 1;
> >
> > -    if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
> > -        if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
> > -            s->g = tile->tile_part[++(*tp_index)].tpg;
> > +    if (tile->has_ppt) {
> > +        s->g = tile->packed_headers_stream;
> > +    } else {
> > +            s->g = tile->tile_part[*tp_index].tpg;
> > +            if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
> > +                if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
> > +                    s->g = tile->tile_part[++(*tp_index)].tpg;
> > +            }
> >          }
> > +        if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
> > +            bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
> >      }
> >
> > -    if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
> > -        bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
> > -
> >      if (!(ret = get_bits(s, 1))) {
> >          jpeg2000_flush(s);
> > -        return 0;
> > +        *process_data = 0;
> > +        goto end;
> >      } else if (ret < 0)
> >          return ret;
> >
> > @@ -1055,6 +1101,34 @@ static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
> >          else
> >              av_log(s->avctx, AV_LOG_ERROR, "EPH marker not found. instead %X\n", bytestream2_peek_be32(&s->g));
> >      }
> > +end:
> > +    if (tile->has_ppt)
> > +        tile->packed_headers_stream = s->g;
> > +    else
> > +        tile->tile_part[*tp_index].tpg = s->g;
> > +    return 0;
> > +}
> > +
> > +static int jpeg2000_decode_packet_data(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
> > +                                       int *tp_index,
> > +                                       Jpeg2000CodingStyle *codsty,
> > +                                       Jpeg2000ResLevel *rlevel, int precno,
> > +                                       int layno, uint8_t *expn, int numgbits)
> > +{
> > +    int bandno, cblkno, nb_code_blocks;
> > +    int cwsno;
> > +
> > +    s->g = tile->tile_part[*tp_index].tpg;
> > +    if (tile->has_ppt) {
> > +        if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
> > +            if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
> > +                s->g = tile->tile_part[++(*tp_index)].tpg;
> > +            }
> > +        }
> > +        if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
> > +            bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
> > +    }
> > +
> >
> >      for (bandno = 0; bandno < rlevel->nbands; bandno++) {
> >          Jpeg2000Band *band = rlevel->band + bandno;
> > @@ -1097,6 +1171,7 @@ static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
> >              av_freep(&cblk->lengthinc);
> >          }
> >      }
> > +    tile->tile_part[*tp_index].tpg = s->g;
> >      return 0;
> >  }
>
> I think this function spliting should be in a seperate patch from adding
> ppt support.
> It would make the changes more readable in the git log
>
I have had lot of trouble understanding how to do this and took the easy route.
I shall just split the function without creating the two new functions
in one patch
as mentioned by Carl.
> thanks
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> I have never wished to cater to the crowd; for what I know they do not
> approve, and what they approve I do not know. -- Epicurus
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-- 
-------------
Gautam |