forked from KolibriOS/kolibrios
374 lines
11 KiB
C
374 lines
11 KiB
C
/*
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* Escape 124 Video Decoder
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* Copyright (C) 2008 Eli Friedman (eli.friedman@gmail.com)
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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#include "internal.h"
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#define BITSTREAM_READER_LE
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#include "get_bits.h"
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typedef union MacroBlock {
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uint16_t pixels[4];
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uint32_t pixels32[2];
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} MacroBlock;
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typedef union SuperBlock {
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uint16_t pixels[64];
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uint32_t pixels32[32];
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} SuperBlock;
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typedef struct CodeBook {
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unsigned depth;
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unsigned size;
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MacroBlock* blocks;
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} CodeBook;
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typedef struct Escape124Context {
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AVFrame frame;
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unsigned num_superblocks;
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CodeBook codebooks[3];
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} Escape124Context;
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/**
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* Initialize the decoder
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* @param avctx decoder context
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* @return 0 success, negative on error
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*/
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static av_cold int escape124_decode_init(AVCodecContext *avctx)
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{
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Escape124Context *s = avctx->priv_data;
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avcodec_get_frame_defaults(&s->frame);
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avctx->pix_fmt = AV_PIX_FMT_RGB555;
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s->num_superblocks = ((unsigned)avctx->width / 8) *
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((unsigned)avctx->height / 8);
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return 0;
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}
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static av_cold int escape124_decode_close(AVCodecContext *avctx)
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{
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unsigned i;
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Escape124Context *s = avctx->priv_data;
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for (i = 0; i < 3; i++)
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av_free(s->codebooks[i].blocks);
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av_frame_unref(&s->frame);
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return 0;
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}
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static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
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unsigned size)
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{
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unsigned i, j;
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CodeBook cb = { 0 };
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if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
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return cb;
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if (size >= INT_MAX / sizeof(MacroBlock))
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return cb;
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cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
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if (!cb.blocks)
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return cb;
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cb.depth = depth;
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cb.size = size;
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for (i = 0; i < size; i++) {
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unsigned mask_bits = get_bits(gb, 4);
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unsigned color0 = get_bits(gb, 15);
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unsigned color1 = get_bits(gb, 15);
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for (j = 0; j < 4; j++) {
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if (mask_bits & (1 << j))
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cb.blocks[i].pixels[j] = color1;
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else
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cb.blocks[i].pixels[j] = color0;
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}
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}
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return cb;
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}
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static unsigned decode_skip_count(GetBitContext* gb)
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{
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unsigned value;
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// This function reads a maximum of 23 bits,
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// which is within the padding space
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if (get_bits_left(gb) < 1)
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return -1;
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value = get_bits1(gb);
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if (!value)
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return value;
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value += get_bits(gb, 3);
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if (value != (1 + ((1 << 3) - 1)))
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return value;
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value += get_bits(gb, 7);
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if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
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return value;
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return value + get_bits(gb, 12);
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}
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static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb,
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int* codebook_index, int superblock_index)
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{
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// This function reads a maximum of 22 bits; the callers
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// guard this function appropriately
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unsigned block_index, depth;
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if (get_bits1(gb)) {
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static const char transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
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*codebook_index = transitions[*codebook_index][get_bits1(gb)];
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}
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depth = s->codebooks[*codebook_index].depth;
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// depth = 0 means that this shouldn't read any bits;
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// in theory, this is the same as get_bits(gb, 0), but
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// that doesn't actually work.
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block_index = depth ? get_bits(gb, depth) : 0;
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if (*codebook_index == 1) {
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block_index += superblock_index << s->codebooks[1].depth;
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}
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// This condition can occur with invalid bitstreams and
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// *codebook_index == 2
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if (block_index >= s->codebooks[*codebook_index].size)
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return (MacroBlock) { { 0 } };
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return s->codebooks[*codebook_index].blocks[block_index];
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}
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static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
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// Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
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uint32_t *dst = sb->pixels32 + index + (index & -4);
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// This technically violates C99 aliasing rules, but it should be safe.
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dst[0] = mb.pixels32[0];
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dst[4] = mb.pixels32[1];
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}
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static void copy_superblock(uint16_t* dest, unsigned dest_stride,
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uint16_t* src, unsigned src_stride)
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{
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unsigned y;
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if (src)
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for (y = 0; y < 8; y++)
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memcpy(dest + y * dest_stride, src + y * src_stride,
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sizeof(uint16_t) * 8);
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else
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for (y = 0; y < 8; y++)
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memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
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}
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static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
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0x4, 0x8, 0x40, 0x80,
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0x100, 0x200, 0x1000, 0x2000,
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0x400, 0x800, 0x4000, 0x8000};
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static int escape124_decode_frame(AVCodecContext *avctx,
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void *data, int *got_frame,
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AVPacket *avpkt)
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{
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int buf_size = avpkt->size;
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Escape124Context *s = avctx->priv_data;
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AVFrame *frame = data;
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GetBitContext gb;
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unsigned frame_flags, frame_size;
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unsigned i;
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unsigned superblock_index, cb_index = 1,
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superblock_col_index = 0,
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superblocks_per_row = avctx->width / 8, skip = -1;
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uint16_t* old_frame_data, *new_frame_data;
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unsigned old_stride, new_stride;
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int ret;
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if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
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return ret;
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// This call also guards the potential depth reads for the
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// codebook unpacking.
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if (get_bits_left(&gb) < 64)
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return -1;
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frame_flags = get_bits_long(&gb, 32);
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frame_size = get_bits_long(&gb, 32);
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// Leave last frame unchanged
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// FIXME: Is this necessary? I haven't seen it in any real samples
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if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
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if (!s->frame.data[0])
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return AVERROR_INVALIDDATA;
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av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
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*got_frame = 1;
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if ((ret = av_frame_ref(frame, &s->frame)) < 0)
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return ret;
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return frame_size;
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}
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for (i = 0; i < 3; i++) {
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if (frame_flags & (1 << (17 + i))) {
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unsigned cb_depth, cb_size;
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if (i == 2) {
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// This codebook can be cut off at places other than
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// powers of 2, leaving some of the entries undefined.
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cb_size = get_bits_long(&gb, 20);
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cb_depth = av_log2(cb_size - 1) + 1;
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} else {
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cb_depth = get_bits(&gb, 4);
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if (i == 0) {
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// This is the most basic codebook: pow(2,depth) entries
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// for a depth-length key
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cb_size = 1 << cb_depth;
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} else {
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// This codebook varies per superblock
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// FIXME: I don't think this handles integer overflow
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// properly
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cb_size = s->num_superblocks << cb_depth;
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}
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}
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av_free(s->codebooks[i].blocks);
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s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
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if (!s->codebooks[i].blocks)
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return -1;
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}
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}
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if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
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return ret;
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new_frame_data = (uint16_t*)frame->data[0];
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new_stride = frame->linesize[0] / 2;
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old_frame_data = (uint16_t*)s->frame.data[0];
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old_stride = s->frame.linesize[0] / 2;
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for (superblock_index = 0; superblock_index < s->num_superblocks;
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superblock_index++) {
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MacroBlock mb;
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SuperBlock sb;
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unsigned multi_mask = 0;
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if (skip == -1) {
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// Note that this call will make us skip the rest of the blocks
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// if the frame prematurely ends
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skip = decode_skip_count(&gb);
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}
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if (skip) {
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copy_superblock(new_frame_data, new_stride,
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old_frame_data, old_stride);
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} else {
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copy_superblock(sb.pixels, 8,
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old_frame_data, old_stride);
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while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
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unsigned mask;
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mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
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mask = get_bits(&gb, 16);
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multi_mask |= mask;
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for (i = 0; i < 16; i++) {
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if (mask & mask_matrix[i]) {
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insert_mb_into_sb(&sb, mb, i);
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}
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}
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}
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if (!get_bits1(&gb)) {
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unsigned inv_mask = get_bits(&gb, 4);
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for (i = 0; i < 4; i++) {
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if (inv_mask & (1 << i)) {
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multi_mask ^= 0xF << i*4;
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} else {
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multi_mask ^= get_bits(&gb, 4) << i*4;
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}
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}
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for (i = 0; i < 16; i++) {
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if (multi_mask & mask_matrix[i]) {
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mb = decode_macroblock(s, &gb, &cb_index,
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superblock_index);
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insert_mb_into_sb(&sb, mb, i);
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}
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}
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} else if (frame_flags & (1 << 16)) {
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while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
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mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
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insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
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}
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}
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copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
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}
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superblock_col_index++;
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new_frame_data += 8;
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if (old_frame_data)
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old_frame_data += 8;
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if (superblock_col_index == superblocks_per_row) {
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new_frame_data += new_stride * 8 - superblocks_per_row * 8;
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if (old_frame_data)
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old_frame_data += old_stride * 8 - superblocks_per_row * 8;
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superblock_col_index = 0;
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}
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skip--;
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}
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av_log(avctx, AV_LOG_DEBUG,
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"Escape sizes: %i, %i, %i\n",
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frame_size, buf_size, get_bits_count(&gb) / 8);
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av_frame_unref(&s->frame);
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if ((ret = av_frame_ref(&s->frame, frame)) < 0)
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return ret;
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*got_frame = 1;
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return frame_size;
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}
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AVCodec ff_escape124_decoder = {
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.name = "escape124",
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.long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
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.type = AVMEDIA_TYPE_VIDEO,
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.id = AV_CODEC_ID_ESCAPE124,
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.priv_data_size = sizeof(Escape124Context),
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.init = escape124_decode_init,
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.close = escape124_decode_close,
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.decode = escape124_decode_frame,
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.capabilities = CODEC_CAP_DR1,
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};
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