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Implement DQT merging

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See #30.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
This commit is contained in:
Derek Buitenhuis
2014-07-31 19:26:09 -04:00
parent 594b7258cc
commit d3a58a33cd
1 changed files with 70 additions and 4 deletions
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74
jcmarker.c
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@@ -183,6 +183,69 @@ emit_dqt (j_compress_ptr cinfo, int index)
return prec;
}
LOCAL(int)
emit_multi_dqt (j_compress_ptr cinfo)
/* Emits a DQT marker containing all quantization tables */
/* Returns number of emitted 16-bit tables, or -1 for failed for baseline checking. */
{
int prec[MAX_COMPONENTS];
int seen[MAX_COMPONENTS] = { 0 };
int fin_prec = 0;
int ci;
for (ci = 0; ci < cinfo->num_components; ci++) {
int tbl_num = cinfo->comp_info[ci].quant_tbl_no;
int i;
JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[tbl_num];
if (qtbl == NULL || qtbl->sent_table == TRUE)
return -1;
prec[ci] = 0;
for (i = 0; i < DCTSIZE2; i++)
prec[ci] = !!(prec[ci] + (qtbl->quantval[i] > 255));
fin_prec += prec[ci];
}
emit_marker(cinfo, M_DQT);
int size = 0;
for (ci = 0; ci < cinfo->num_components; ci++) {
int tbl_num = cinfo->comp_info[ci].quant_tbl_no;
if (!seen[tbl_num]) {
size += DCTSIZE2 * (prec[ci] + 1) + 1;
seen[tbl_num] = 1;
}
}
size += 2;
emit_2bytes(cinfo, size);
for (ci = 0; ci < cinfo->num_components; ci++) {
int tbl_num = cinfo->comp_info[ci].quant_tbl_no;
int i;
JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[tbl_num];
if (qtbl->sent_table == TRUE)
continue;
emit_byte(cinfo, tbl_num + (prec[ci] << 4));
for (i = 0; i < DCTSIZE2; i++) {
unsigned int qval = qtbl->quantval[jpeg_natural_order[i]];
if (prec[ci])
emit_byte(cinfo, (int) (qval >> 8));
emit_byte(cinfo, (int) (qval & 0xFF));
}
qtbl->sent_table = TRUE;
}
return fin_prec;
}
LOCAL(void)
emit_dht (j_compress_ptr cinfo, int index, boolean is_ac)
@@ -504,10 +567,13 @@ write_frame_header (j_compress_ptr cinfo)
/* Emit DQT for each quantization table.
* Note that emit_dqt() suppresses any duplicate tables.
*/
prec = 0;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
prec += emit_dqt(cinfo, compptr->quant_tbl_no);
prec = emit_multi_dqt(cinfo);
if (prec == -1) {
prec = 0;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
prec += emit_dqt(cinfo, compptr->quant_tbl_no);
}
}
/* now prec is nonzero iff there are any 16-bit quant tables. */