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Packet header writing: set empty packet header bit to 0 when appropriate (small optimization)

This commit is contained in:
Even Rouault 2017-06-12 17:15:23 +01:00
parent 73d1510d47
commit 2609fb8077
1 changed files with 35 additions and 3 deletions
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38
src/lib/openjp2/t2.c
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@ -611,6 +611,7 @@ static OPJ_BOOL opj_t2_encode_packet(OPJ_UINT32 tileno,
opj_tcd_resolution_t *res = &tilec->resolutions[resno]; opj_tcd_resolution_t *res = &tilec->resolutions[resno];
opj_bio_t *bio = 00; /* BIO component */ opj_bio_t *bio = 00; /* BIO component */
OPJ_BOOL packet_empty = OPJ_TRUE;
/* <SOP 0xff91> */ /* <SOP 0xff91> */
if (tcp->csty & J2K_CP_CSTY_SOP) { if (tcp->csty & J2K_CP_CSTY_SOP) {
@ -661,11 +662,42 @@ static OPJ_BOOL opj_t2_encode_packet(OPJ_UINT32 tileno,
return OPJ_FALSE; return OPJ_FALSE;
} }
opj_bio_init_enc(bio, c, length); opj_bio_init_enc(bio, c, length);
opj_bio_write(bio, 1, 1); /* Empty header bit */
/* Check if the packet is empty */
/* Note: we could also skip that step and always write a packet header */
band = res->bands;
for (bandno = 0; bandno < res->numbands; ++bandno, ++band) {
opj_tcd_precinct_t *prc;
/* Skip empty bands */
if (opj_tcd_is_band_empty(band)) {
continue;
}
prc = &band->precincts[precno];
l_nb_blocks = prc->cw * prc->ch;
cblk = prc->cblks.enc;
for (cblkno = 0; cblkno < l_nb_blocks; cblkno++, ++cblk) {
opj_tcd_layer_t *layer = &cblk->layers[layno];
/* if cblk not included, go to the next cblk */
if (!layer->numpasses) {
continue;
}
packet_empty = OPJ_FALSE;
break;
}
if (!packet_empty) {
break;
}
}
opj_bio_write(bio, packet_empty ? 0 : 1, 1); /* Empty header bit */
/* Writing Packet header */ /* Writing Packet header */
band = res->bands; band = res->bands;
for (bandno = 0; bandno < res->numbands; ++bandno, ++band) { for (bandno = 0; !packet_empty &&
bandno < res->numbands; ++bandno, ++band) {
opj_tcd_precinct_t *prc; opj_tcd_precinct_t *prc;
/* Skip empty bands */ /* Skip empty bands */
@ -789,7 +821,7 @@ static OPJ_BOOL opj_t2_encode_packet(OPJ_UINT32 tileno,
/* Writing the packet body */ /* Writing the packet body */
band = res->bands; band = res->bands;
for (bandno = 0; bandno < res->numbands; bandno++, ++band) { for (bandno = 0; !packet_empty && bandno < res->numbands; bandno++, ++band) {
opj_tcd_precinct_t *prc; opj_tcd_precinct_t *prc;
/* Skip empty bands */ /* Skip empty bands */