From 6b00202f1ba30f3546d6e6f277ec396cf45a76d0 Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Mon, 28 Oct 2013 21:43:05 +0100
Subject: [PATCH] vp9/decode: add get_tile()
factorizes the code in decode_tiles(). reading the offsets backwards
wasn't doing anything to prove tile independence
Change-Id: I0395d3c77205852ebdc55efedc68291e93cef85c
---
vp9/decoder/vp9_decodframe.c | 58 +++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 27 deletions(-)
diff --git a/vp9/decoder/vp9_decodframe.c b/vp9/decoder/vp9_decodframe.c
index 40cab68e8b..a13d49e370 100644
--- a/vp9/decoder/vp9_decodframe.c
+++ b/vp9/decoder/vp9_decodframe.c
@@ -823,6 +823,27 @@ static void setup_tile_info(VP9_COMMON *cm, struct vp9_read_bit_buffer *rb) {
cm->log2_tile_rows += vp9_rb_read_bit(rb);
}
+// Reads the next tile returning its size and adjusting '*data' accordingly
+// based on 'is_last'.
+static size_t get_tile(const uint8_t *const data_end,
+ int is_last,
+ struct vpx_internal_error_info *error_info,
+ const uint8_t **data) {
+ size_t size;
+
+ if (!is_last) {
+ if (!read_is_valid(*data, 4, data_end))
+ vpx_internal_error(error_info, VPX_CODEC_CORRUPT_FRAME,
+ "Truncated packet or corrupt tile length");
+
+ size = read_be32(*data);
+ *data += 4;
+ } else {
+ size = data_end - *data;
+ }
+ return size;
+}
+
static const uint8_t *decode_tiles(VP9D_COMP *pbi, const uint8_t *data) {
vp9_reader residual_bc;
@@ -848,20 +869,15 @@ static const uint8_t *decode_tiles(VP9D_COMP *pbi, const uint8_t *data) {
const uint8_t *data_ptr2[4][1 << 6];
vp9_reader bc_bak = {0};
- // pre-initialize the offsets, we're going to read in inverse order
+ // pre-initialize the offsets, we're going to decode in inverse order
data_ptr2[0][0] = data;
for (tile_row = 0; tile_row < tile_rows; tile_row++) {
- if (tile_row) {
- const int size = read_be32(data_ptr2[tile_row - 1][tile_cols - 1]);
- data_ptr2[tile_row - 1][tile_cols - 1] += 4;
- data_ptr2[tile_row][0] = data_ptr2[tile_row - 1][tile_cols - 1] + size;
- }
-
- for (tile_col = 1; tile_col < tile_cols; tile_col++) {
- const int size = read_be32(data_ptr2[tile_row][tile_col - 1]);
- data_ptr2[tile_row][tile_col - 1] += 4;
- data_ptr2[tile_row][tile_col] =
- data_ptr2[tile_row][tile_col - 1] + size;
+ for (tile_col = 0; tile_col < tile_cols; tile_col++) {
+ const int last_tile =
+ tile_row == tile_rows - 1 && tile_col == tile_cols - 1;
+ const size_t size = get_tile(data_end, last_tile, &cm->error, &data);
+ data_ptr2[tile_row][tile_col] = data;
+ data += size;
}
}
@@ -881,27 +897,15 @@ static const uint8_t *decode_tiles(VP9D_COMP *pbi, const uint8_t *data) {
}
residual_bc = bc_bak;
} else {
- int has_more;
-
for (tile_row = 0; tile_row < tile_rows; tile_row++) {
for (tile_col = 0; tile_col < tile_cols; tile_col++) {
+ const int last_tile =
+ tile_row == tile_rows - 1 && tile_col == tile_cols - 1;
+ const size_t size = get_tile(data_end, last_tile, &cm->error, &data);
TileInfo tile;
- size_t size;
vp9_tile_init(&tile, cm, tile_row, tile_col);
- has_more = tile_col < tile_cols - 1 || tile_row < tile_rows - 1;
- if (has_more) {
- if (!read_is_valid(data, 4, data_end))
- vpx_internal_error(&cm->error, VPX_CODEC_CORRUPT_FRAME,
- "Truncated packet or corrupt tile length");
-
- size = read_be32(data);
- data += 4;
- } else {
- size = data_end - data;
- }
-
setup_token_decoder(data, data_end, size, &cm->error, &residual_bc);
setup_tile_context(pbi, xd, tile_col);
decode_tile(pbi, &tile, &residual_bc);
--
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