Improve the tile based decoding performance
Change-Id: I4043edff510ffe50fdf47a342d6a95e879918737
diff --git a/jdapistd.c b/jdapistd.c
index 8d6e591..e1233df 100644
--- a/jdapistd.c
+++ b/jdapistd.c
@@ -221,6 +221,9 @@
int col_right_boundary =
jdiv_round_up(*start_x + *width, lines_per_iMCU_col);
+ cinfo->coef->MCU_columns_to_skip =
+ *start_x / lines_per_iMCU_col - col_left_boundary;
+
*height = (*start_y - row_offset * lines_per_iMCU_row) + *height;
*start_x = col_left_boundary * lines_per_iMCU_col;
*start_y = row_offset * lines_per_iMCU_row;
diff --git a/jdcoefct.c b/jdcoefct.c
index b10f9bc..9e8040b 100644
--- a/jdcoefct.c
+++ b/jdcoefct.c
@@ -170,13 +170,18 @@
for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
MCU_col_num++) {
/* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
- jzero_far((void FAR *) coef->MCU_buffer[0],
+ if (MCU_col_num < coef->pub.MCU_columns_to_skip) {
+ (*cinfo->entropy->decode_mcu_discard_coef) (cinfo);
+ continue;
+ } else {
+ jzero_far((void FAR *) coef->MCU_buffer[0],
(size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
- if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
- /* Suspension forced; update state counters and exit */
- coef->MCU_vert_offset = yoffset;
- coef->MCU_ctr = MCU_col_num;
- return JPEG_SUSPENDED;
+ if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
+ /* Suspension forced; update state counters and exit */
+ coef->MCU_vert_offset = yoffset;
+ coef->MCU_ctr = MCU_col_num;
+ return JPEG_SUSPENDED;
+ }
}
/* Determine where data should go in output_buf and do the IDCT thing.
* We skip dummy blocks at the right and bottom edges (but blkn gets
@@ -203,8 +208,8 @@
output_col = start_col;
for (xindex = 0; xindex < useful_width; xindex++) {
(*inverse_DCT) (cinfo, compptr,
- (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
- output_ptr, output_col);
+ (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
+ output_ptr, output_col);
output_col += compptr->DCT_scaled_size;
}
}
@@ -575,11 +580,25 @@
}
inverse_DCT = cinfo->idct->inverse_DCT[ci];
output_ptr = output_buf[ci];
+ int width_in_blocks = compptr->width_in_blocks;
+ int start_block = 0;
+#if ANDROID_TILE_BASED_DECODE
+ if (cinfo->tile_decode) {
+ width_in_blocks = jmin(width_in_blocks,
+ (cinfo->coef->MCU_column_right_boundary -
+ cinfo->coef->MCU_column_left_boundary) *
+ cinfo->max_h_samp_factor /
+ compptr->h_samp_factor);
+ start_block = coef->pub.MCU_columns_to_skip *
+ cinfo->max_h_samp_factor / compptr->h_samp_factor;
+ }
+#endif
/* Loop over all DCT blocks to be processed. */
for (block_row = 0; block_row < block_rows; block_row++) {
buffer_ptr = buffer[block_row];
- output_col = 0;
- for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
+ output_col = start_block * compptr->DCT_scaled_size;
+ buffer_ptr += start_block;
+ for (block_num = start_block; block_num < width_in_blocks; block_num++) {
(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
output_ptr, output_col);
buffer_ptr++;
@@ -906,6 +925,7 @@
coef->pub.start_output_pass = start_output_pass;
coef->pub.column_left_boundary = 0;
coef->pub.column_right_boundary = 0;
+ coef->pub.MCU_columns_to_skip = 0;
#ifdef BLOCK_SMOOTHING_SUPPORTED
coef->coef_bits_latch = NULL;
#endif
diff --git a/jpegint.h b/jpegint.h
index fd6d8bb..3b5511e 100644
--- a/jpegint.h
+++ b/jpegint.h
@@ -177,10 +177,20 @@
JSAMPIMAGE output_buf));
/* Pointer to array of coefficient virtual arrays, or NULL if none */
jvirt_barray_ptr *coef_arrays;
+
+ /* column number of the first and last tile, respectively */
int column_left_boundary;
int column_right_boundary;
+
+ /* column number of the first and last MCU, respectively */
int MCU_column_left_boundary;
int MCU_column_right_boundary;
+
+ /* the number of MCU columns to skip from the indexed MCU, iM,
+ * to the requested MCU boundary, rM, where iM is the MCU that we sample
+ * into our index and is the nearest one to the left of rM.
+ */
+ int MCU_columns_to_skip;
};
/* Decompression postprocessing (color quantization buffer control) */
