Skip to content

F
ffmpeg.wasm-core
Commit c43eb731 authored by Alexandra Hájková's avatar Alexandra Hájková Committed by Anton Khirnov
Browse files
Options

escape124: Convert to the new bitstream reader 

Signed-off-by: 's avatarAnton Khirnov <anton@khirnov.net>
parent d8618570
Hide whitespace changes
Inline Side-by-side
Showing with 41 additions and 44 deletions
libavcodec/escape124.c
View file @ c43eb731
......@@ -21,7 +21,7 @@
#define BITSTREAM_READER_LE
#include "avcodec.h"
#include "get_bits.h"
#include "bitstream.h"
#include "internal.h"
typedef union MacroBlock {
......@@ -48,8 +48,9 @@ typedef struct Escape124Context {
CodeBook codebooks[3];
} Escape124Context;
static int can_safely_read(GetBitContext* gb, int bits) {
return get_bits_left(gb) >= bits;
static int can_safely_read(BitstreamContext *bc, int bits)
{
return bitstream_bits_left(bc) >= bits;
}
/**
......@@ -86,13 +87,13 @@ static av_cold int escape124_decode_close(AVCodecContext *avctx)
return 0;
}
static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
static CodeBook unpack_codebook(BitstreamContext *bc, unsigned depth,
unsigned size)
{
unsigned i, j;
CodeBook cb = { 0 };
if (!can_safely_read(gb, size * 34))
if (!can_safely_read(bc, size * 34))
return cb;
if (size >= INT_MAX / sizeof(MacroBlock))
......@@ -104,9 +105,9 @@ static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
cb.depth = depth;
cb.size = size;
for (i = 0; i < size; i++) {
unsigned mask_bits = get_bits(gb, 4);
unsigned color0 = get_bits(gb, 15);
unsigned color1 = get_bits(gb, 15);
unsigned mask_bits = bitstream_read(bc, 4);
unsigned color0 = bitstream_read(bc, 15);
unsigned color1 = bitstream_read(bc, 15);
for (j = 0; j < 4; j++) {
if (mask_bits & (1 << j))
......@@ -118,47 +119,43 @@ static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
return cb;
}
static unsigned decode_skip_count(GetBitContext* gb)
static unsigned decode_skip_count(BitstreamContext *bc)
{
unsigned value;
// This function reads a maximum of 23 bits,
// which is within the padding space
if (!can_safely_read(gb, 1))
if (!can_safely_read(bc, 1))
return -1;
value = get_bits1(gb);
value = bitstream_read_bit(bc);
if (!value)
return value;
value += get_bits(gb, 3);
value += bitstream_read(bc, 3);
if (value != (1 + ((1 << 3) - 1)))
return value;
value += get_bits(gb, 7);
value += bitstream_read(bc, 7);
if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
return value;
return value + get_bits(gb, 12);
return value + bitstream_read(bc, 12);
}
static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb,
int* codebook_index, int superblock_index)
static MacroBlock decode_macroblock(Escape124Context *s, BitstreamContext *bc,
int *codebook_index, int superblock_index)
{
// This function reads a maximum of 22 bits; the callers
// guard this function appropriately
unsigned block_index, depth;
int value = get_bits1(gb);
int value = bitstream_read_bit(bc);
if (value) {
static const char transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
value = get_bits1(gb);
value = bitstream_read_bit(bc);
*codebook_index = transitions[*codebook_index][value];
}
depth = s->codebooks[*codebook_index].depth;
// depth = 0 means that this shouldn't read any bits;
// in theory, this is the same as get_bits(gb, 0), but
// that doesn't actually work.
block_index = get_bitsz(gb, depth);
block_index = bitstream_read(bc, depth);
if (*codebook_index == 1) {
block_index += superblock_index << s->codebooks[1].depth;
......@@ -208,7 +205,7 @@ static int escape124_decode_frame(AVCodecContext *avctx,
Escape124Context *s = avctx->priv_data;
AVFrame *frame = data;
GetBitContext gb;
BitstreamContext bc;
unsigned frame_flags, frame_size;
unsigned i;
......@@ -220,15 +217,15 @@ static int escape124_decode_frame(AVCodecContext *avctx,
unsigned old_stride, new_stride;
int ret;
init_get_bits(&gb, buf, buf_size * 8);
bitstream_init(&bc, buf, buf_size * 8);
// This call also guards the potential depth reads for the
// codebook unpacking.
if (!can_safely_read(&gb, 64))
if (!can_safely_read(&bc, 64))
return -1;
frame_flags = get_bits_long(&gb, 32);
frame_size = get_bits_long(&gb, 32);
frame_flags = bitstream_read(&bc, 32);
frame_size = bitstream_read(&bc, 32);
// Leave last frame unchanged
// FIXME: Is this necessary? I haven't seen it in any real samples
......@@ -251,10 +248,10 @@ static int escape124_decode_frame(AVCodecContext *avctx,
if (i == 2) {
// This codebook can be cut off at places other than
// powers of 2, leaving some of the entries undefined.
cb_size = get_bits_long(&gb, 20);
cb_size = bitstream_read(&bc, 20);
cb_depth = av_log2(cb_size - 1) + 1;
} else {
cb_depth = get_bits(&gb, 4);
cb_depth = bitstream_read(&bc, 4);
if (i == 0) {
// This is the most basic codebook: pow(2,depth) entries
// for a depth-length key
......@@ -267,7 +264,7 @@ static int escape124_decode_frame(AVCodecContext *avctx,
}
}
av_free(s->codebooks[i].blocks);
s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
s->codebooks[i] = unpack_codebook(&bc, cb_depth, cb_size);
if (!s->codebooks[i].blocks)
return -1;
}
......@@ -292,7 +289,7 @@ static int escape124_decode_frame(AVCodecContext *avctx,
if (skip == -1) {
// Note that this call will make us skip the rest of the blocks
// if the frame prematurely ends
skip = decode_skip_count(&gb);
skip = decode_skip_count(&bc);
}
if (skip) {
......@@ -302,10 +299,10 @@ static int escape124_decode_frame(AVCodecContext *avctx,
copy_superblock(sb.pixels, 8,
old_frame_data, old_stride);
while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
while (can_safely_read(&bc, 1) && !bitstream_read_bit(&bc)) {
unsigned mask;
mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
mask = get_bits(&gb, 16);
mb = decode_macroblock(s, &bc, &cb_index, superblock_index);
mask = bitstream_read(&bc, 16);
multi_mask |= mask;
for (i = 0; i < 16; i++) {
if (mask & mask_matrix[i]) {
......@@ -314,29 +311,29 @@ static int escape124_decode_frame(AVCodecContext *avctx,
}
}
if (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
unsigned inv_mask = get_bits(&gb, 4);
if (can_safely_read(&bc, 1) && !bitstream_read_bit(&bc)) {
unsigned inv_mask = bitstream_read(&bc, 4);
for (i = 0; i < 4; i++) {
if (inv_mask & (1 << i)) {
multi_mask ^= 0xF << i*4;
} else {
multi_mask ^= get_bits(&gb, 4) << i*4;
multi_mask ^= bitstream_read(&bc, 4) << i * 4;
}
}
for (i = 0; i < 16; i++) {
if (multi_mask & mask_matrix[i]) {
if (!can_safely_read(&gb, 1))
if (!can_safely_read(&bc, 1))
break;
mb = decode_macroblock(s, &gb, &cb_index,
mb = decode_macroblock(s, &bc, &cb_index,
superblock_index);
insert_mb_into_sb(&sb, mb, i);
}
}
} else if (frame_flags & (1 << 16)) {
while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
while (can_safely_read(&bc, 1) && !bitstream_read_bit(&bc)) {
mb = decode_macroblock(s, &bc, &cb_index, superblock_index);
insert_mb_into_sb(&sb, mb, bitstream_read(&bc, 4));
}
}
......@@ -358,7 +355,7 @@ static int escape124_decode_frame(AVCodecContext *avctx,
av_log(NULL, AV_LOG_DEBUG,
"Escape sizes: %i, %i, %i\n",
frame_size, buf_size, get_bits_count(&gb) / 8);
frame_size, buf_size, bitstream_tell(&bc) / 8);
av_frame_unref(s->frame);
if ((ret = av_frame_ref(s->frame, frame)) < 0)
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment