| /* | |
| * Escape 124 Video Decoder | |
| * Copyright (C) 2008 Eli Friedman (eli.friedman@gmail.com) | |
| * | |
| * This file is part of FFmpeg. | |
| * | |
| * FFmpeg is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 of the License, or (at your option) any later version. | |
| * | |
| * FFmpeg is distributed in the hope that it will be useful, | |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| * Lesser General Public License for more details. | |
| * | |
| * You should have received a copy of the GNU Lesser General Public | |
| * License along with FFmpeg; if not, write to the Free Software | |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| */ | |
| #define BITSTREAM_READER_LE | |
| #include "avcodec.h" | |
| #include "codec_internal.h" | |
| #include "decode.h" | |
| #include "get_bits.h" | |
| typedef union MacroBlock { | |
| uint16_t pixels[4]; | |
| uint32_t pixels32[2]; | |
| } MacroBlock; | |
| typedef union SuperBlock { | |
| uint16_t pixels[64]; | |
| uint32_t pixels32[32]; | |
| } SuperBlock; | |
| typedef struct CodeBook { | |
| unsigned depth; | |
| unsigned size; | |
| MacroBlock* blocks; | |
| } CodeBook; | |
| typedef struct Escape124Context { | |
| AVFrame *frame; | |
| unsigned num_superblocks; | |
| CodeBook codebooks[3]; | |
| } Escape124Context; | |
| /** | |
| * Initialize the decoder | |
| * @param avctx decoder context | |
| * @return 0 success, negative on error | |
| */ | |
| static av_cold int escape124_decode_init(AVCodecContext *avctx) | |
| { | |
| Escape124Context *s = avctx->priv_data; | |
| avctx->pix_fmt = AV_PIX_FMT_RGB555; | |
| s->num_superblocks = ((unsigned)avctx->width / 8) * | |
| ((unsigned)avctx->height / 8); | |
| s->frame = av_frame_alloc(); | |
| if (!s->frame) | |
| return AVERROR(ENOMEM); | |
| return 0; | |
| } | |
| static av_cold int escape124_decode_close(AVCodecContext *avctx) | |
| { | |
| unsigned i; | |
| Escape124Context *s = avctx->priv_data; | |
| for (i = 0; i < 3; i++) | |
| av_freep(&s->codebooks[i].blocks); | |
| av_frame_free(&s->frame); | |
| return 0; | |
| } | |
| static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth, | |
| unsigned size) | |
| { | |
| unsigned i, j; | |
| CodeBook cb = { 0 }; | |
| cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1); | |
| if (!cb.blocks) | |
| return cb; | |
| cb.depth = depth; | |
| cb.size = size; | |
| for (i = 0; i < size; i++) { | |
| unsigned mask_bits = get_bits(gb, 4); | |
| unsigned color[2]; | |
| color[0] = get_bits(gb, 15); | |
| color[1] = get_bits(gb, 15); | |
| for (j = 0; j < 4; j++) | |
| cb.blocks[i].pixels[j] = color[(mask_bits>>j) & 1]; | |
| } | |
| return cb; | |
| } | |
| static unsigned decode_skip_count(GetBitContext* gb) | |
| { | |
| unsigned value; | |
| // This function reads a maximum of 23 bits, | |
| // which is within the padding space | |
| if (get_bits_left(gb) < 1) | |
| return -1; | |
| value = get_bits1(gb); | |
| if (!value) | |
| return value; | |
| value += get_bits(gb, 3); | |
| if (value != (1 + ((1 << 3) - 1))) | |
| return value; | |
| value += get_bits(gb, 7); | |
| if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1)) | |
| return value; | |
| return value + get_bits(gb, 12); | |
| } | |
| static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb, | |
| 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); | |
| if (value) { | |
| static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} }; | |
| value = get_bits1(gb); | |
| *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); | |
| if (*codebook_index == 1) { | |
| block_index += superblock_index << s->codebooks[1].depth; | |
| } | |
| // This condition can occur with invalid bitstreams and | |
| // *codebook_index == 2 | |
| if (block_index >= s->codebooks[*codebook_index].size || !s->codebooks[*codebook_index].blocks) | |
| return (MacroBlock) { { 0 } }; | |
| return s->codebooks[*codebook_index].blocks[block_index]; | |
| } | |
| static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) { | |
| // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2 | |
| uint32_t *dst = sb->pixels32 + index + (index & -4); | |
| // This technically violates C99 aliasing rules, but it should be safe. | |
| dst[0] = mb.pixels32[0]; | |
| dst[4] = mb.pixels32[1]; | |
| } | |
| static void copy_superblock(uint16_t* dest, ptrdiff_t dest_stride, | |
| uint16_t* src, ptrdiff_t src_stride) | |
| { | |
| unsigned y; | |
| if (src) | |
| for (y = 0; y < 8; y++) | |
| memcpy(dest + y * dest_stride, src + y * src_stride, | |
| sizeof(uint16_t) * 8); | |
| else | |
| for (y = 0; y < 8; y++) | |
| memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8); | |
| } | |
| static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20, | |
| 0x4, 0x8, 0x40, 0x80, | |
| 0x100, 0x200, 0x1000, 0x2000, | |
| 0x400, 0x800, 0x4000, 0x8000}; | |
| static int escape124_decode_frame(AVCodecContext *avctx, AVFrame *frame, | |
| int *got_frame, AVPacket *avpkt) | |
| { | |
| int buf_size = avpkt->size; | |
| Escape124Context *s = avctx->priv_data; | |
| GetBitContext gb; | |
| unsigned frame_flags, frame_size; | |
| unsigned i; | |
| unsigned superblock_index, cb_index = 1, | |
| superblock_col_index = 0, | |
| superblocks_per_row = avctx->width / 8, skip = -1; | |
| uint16_t* old_frame_data, *new_frame_data; | |
| ptrdiff_t old_stride, new_stride; | |
| int ret; | |
| if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0) | |
| return ret; | |
| // This call also guards the potential depth reads for the | |
| // codebook unpacking. | |
| // Check if the amount we will read minimally is available on input. | |
| // The 64 represent the immediately next 2 frame_* elements read, the 23/4320 | |
| // represent a lower bound of the space needed for skipped superblocks. Non | |
| // skipped SBs need more space. | |
| if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320) | |
| return AVERROR_INVALIDDATA; | |
| frame_flags = get_bits_long(&gb, 32); | |
| frame_size = get_bits_long(&gb, 32); | |
| // Leave last frame unchanged | |
| // FIXME: Is this necessary? I haven't seen it in any real samples | |
| if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) { | |
| if (!s->frame->data[0]) | |
| return AVERROR_INVALIDDATA; | |
| av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n"); | |
| *got_frame = 1; | |
| if ((ret = av_frame_ref(frame, s->frame)) < 0) | |
| return ret; | |
| return 0; | |
| } | |
| for (i = 0; i < 3; i++) { | |
| if (frame_flags & (1 << (17 + i))) { | |
| unsigned cb_depth, cb_size; | |
| 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(&gb, 20); | |
| if (!cb_size) { | |
| av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n"); | |
| return AVERROR_INVALIDDATA; | |
| } | |
| cb_depth = av_log2(cb_size - 1) + 1; | |
| } else { | |
| cb_depth = get_bits(&gb, 4); | |
| if (i == 0) { | |
| // This is the most basic codebook: pow(2,depth) entries | |
| // for a depth-length key | |
| cb_size = 1 << cb_depth; | |
| } else { | |
| // This codebook varies per superblock | |
| // FIXME: I don't think this handles integer overflow | |
| // properly | |
| cb_size = s->num_superblocks << cb_depth; | |
| } | |
| } | |
| if (s->num_superblocks >= INT_MAX >> cb_depth) { | |
| av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n"); | |
| return AVERROR_INVALIDDATA; | |
| } | |
| av_freep(&s->codebooks[i].blocks); | |
| if (cb_size >= INT_MAX / 34 || get_bits_left(&gb) < (int)cb_size * 34) | |
| return AVERROR_INVALIDDATA; | |
| if (cb_size >= INT_MAX / sizeof(MacroBlock)) | |
| return AVERROR_INVALIDDATA; | |
| s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size); | |
| if (!s->codebooks[i].blocks) | |
| return AVERROR(ENOMEM); | |
| } | |
| } | |
| if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0) | |
| return ret; | |
| new_frame_data = (uint16_t*)frame->data[0]; | |
| new_stride = frame->linesize[0] / 2; | |
| old_frame_data = (uint16_t*)s->frame->data[0]; | |
| old_stride = s->frame->linesize[0] / 2; | |
| for (superblock_index = 0; superblock_index < s->num_superblocks; | |
| superblock_index++) { | |
| MacroBlock mb; | |
| SuperBlock sb; | |
| unsigned multi_mask = 0; | |
| 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); | |
| } | |
| if (skip) { | |
| copy_superblock(new_frame_data, new_stride, | |
| old_frame_data, old_stride); | |
| } else { | |
| copy_superblock(sb.pixels, 8, | |
| old_frame_data, old_stride); | |
| while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) { | |
| unsigned mask; | |
| mb = decode_macroblock(s, &gb, &cb_index, superblock_index); | |
| mask = get_bits(&gb, 16); | |
| multi_mask |= mask; | |
| for (i = 0; i < 16; i++) { | |
| if (mask & mask_matrix[i]) { | |
| insert_mb_into_sb(&sb, mb, i); | |
| } | |
| } | |
| } | |
| if (!get_bits1(&gb)) { | |
| unsigned inv_mask = get_bits(&gb, 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; | |
| } | |
| } | |
| for (i = 0; i < 16; i++) { | |
| if (multi_mask & mask_matrix[i]) { | |
| mb = decode_macroblock(s, &gb, &cb_index, | |
| superblock_index); | |
| insert_mb_into_sb(&sb, mb, i); | |
| } | |
| } | |
| } else if (frame_flags & (1 << 16)) { | |
| while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) { | |
| mb = decode_macroblock(s, &gb, &cb_index, superblock_index); | |
| insert_mb_into_sb(&sb, mb, get_bits(&gb, 4)); | |
| } | |
| } | |
| copy_superblock(new_frame_data, new_stride, sb.pixels, 8); | |
| } | |
| superblock_col_index++; | |
| new_frame_data += 8; | |
| if (old_frame_data) | |
| old_frame_data += 8; | |
| if (superblock_col_index == superblocks_per_row) { | |
| new_frame_data += new_stride * 8 - superblocks_per_row * 8; | |
| if (old_frame_data) | |
| old_frame_data += old_stride * 8 - superblocks_per_row * 8; | |
| superblock_col_index = 0; | |
| } | |
| skip--; | |
| } | |
| av_log(avctx, AV_LOG_DEBUG, | |
| "Escape sizes: %i, %i, %i\n", | |
| frame_size, buf_size, get_bits_count(&gb) / 8); | |
| if ((ret = av_frame_replace(s->frame, frame)) < 0) | |
| return ret; | |
| *got_frame = 1; | |
| return 0; | |
| } | |
| const FFCodec ff_escape124_decoder = { | |
| .p.name = "escape124", | |
| CODEC_LONG_NAME("Escape 124"), | |
| .p.type = AVMEDIA_TYPE_VIDEO, | |
| .p.id = AV_CODEC_ID_ESCAPE124, | |
| .priv_data_size = sizeof(Escape124Context), | |
| .init = escape124_decode_init, | |
| .close = escape124_decode_close, | |
| FF_CODEC_DECODE_CB(escape124_decode_frame), | |
| .p.capabilities = AV_CODEC_CAP_DR1, | |
| }; |