/* * Flash Screen Video decoder * Copyright (C) 2004 Alex Beregszaszi * Copyright (C) 2006 Benjamin Larsson * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * Flash Screen Video decoder * @author Alex Beregszaszi * @author Benjamin Larsson */ /* Bitstream description * The picture is divided into blocks that are zlib compressed. * * The decoder is fed complete frames, the frameheader contains: * 4bits of block width * 12bits of frame width * 4bits of block height * 12bits of frame height * * Directly after the header are the compressed blocks. The blocks * have their compressed size represented with 16bits in the beginnig. * If the size = 0 then the block is unchanged from the previous frame. * All blocks are decompressed until the buffer is consumed. * * Encoding ideas, a basic encoder would just use a fixed block size. * Block sizes can be multipels of 16, from 16 to 256. The blocks don't * have to be quadratic. A brute force search with a set of diffrent * block sizes should give a better result then to just use a fixed size. */ #include #include #include #include "avcodec.h" #include "get_bits.h" typedef struct FlashSVContext { AVCodecContext *avctx; AVFrame frame; int image_width, image_height; int block_width, block_height; uint8_t *tmpblock; int block_size; z_stream zstream; } FlashSVContext; static void copy_region(uint8_t *sptr, uint8_t *dptr, int dx, int dy, int h, int w, int stride) { int i; for (i = dx + h; i > dx; i--) { memcpy(dptr + i * stride + dy * 3, sptr, w * 3); sptr += w * 3; } } static av_cold int flashsv_decode_init(AVCodecContext *avctx) { FlashSVContext *s = avctx->priv_data; int zret; // Zlib return code s->avctx = avctx; s->zstream.zalloc = Z_NULL; s->zstream.zfree = Z_NULL; s->zstream.opaque = Z_NULL; zret = inflateInit(&s->zstream); if (zret != Z_OK) { av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret); return 1; } avctx->pix_fmt = PIX_FMT_BGR24; s->frame.data[0] = NULL; return 0; } static int flashsv_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) { const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; FlashSVContext *s = avctx->priv_data; int h_blocks, v_blocks, h_part, v_part, i, j; GetBitContext gb; /* no supplementary picture */ if (buf_size == 0) return 0; if (buf_size < 4) return -1; init_get_bits(&gb, buf, buf_size * 8); /* start to parse the bitstream */ s->block_width = 16 * (get_bits(&gb, 4) + 1); s->image_width = get_bits(&gb, 12); s->block_height = 16 * (get_bits(&gb, 4) + 1); s->image_height = get_bits(&gb, 12); /* calculate amount of blocks and the size of the border blocks */ h_blocks = s->image_width / s->block_width; h_part = s->image_width % s->block_width; v_blocks = s->image_height / s->block_height; v_part = s->image_height % s->block_height; /* the block size could change between frames, make sure the buffer * is large enough, if not, get a larger one */ if (s->block_size < s->block_width * s->block_height) { av_free(s->tmpblock); if ((s->tmpblock = av_malloc(3 * s->block_width * s->block_height)) == NULL) { av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n"); return AVERROR(ENOMEM); } } s->block_size = s->block_width * s->block_height; /* init the image size once */ if (avctx->width == 0 && avctx->height == 0) { avctx->width = s->image_width; avctx->height = s->image_height; } /* check for changes of image width and image height */ if (avctx->width != s->image_width || avctx->height != s->image_height) { av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n"); av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n", avctx->height, avctx->width, s->image_height, s->image_width); return AVERROR_INVALIDDATA; } av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n", s->image_width, s->image_height, s->block_width, s->block_height, h_blocks, v_blocks, h_part, v_part); s->frame.reference = 1; s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE; if (avctx->reget_buffer(avctx, &s->frame) < 0) { av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n"); return -1; } /* loop over all block columns */ for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) { int hp = j * s->block_height; // horiz position in frame int hs = (j < v_blocks) ? s->block_height : v_part; // size of block /* loop over all block rows */ for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) { int wp = i * s->block_width; // vert position in frame int ws = (i < h_blocks) ? s->block_width : h_part; // size of block /* get the size of the compressed zlib chunk */ int size = get_bits(&gb, 16); if (8 * size > get_bits_left(&gb)) { avctx->release_buffer(avctx, &s->frame); s->frame.data[0] = NULL; return AVERROR_INVALIDDATA; } if (size == 0) { /* no change, don't do anything */ } else { /* decompress block */ int ret = inflateReset(&s->zstream); if (ret != Z_OK) { av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j); /* return -1; */ } s->zstream.next_in = buf + get_bits_count(&gb) / 8; s->zstream.avail_in = size; s->zstream.next_out = s->tmpblock; s->zstream.avail_out = s->block_size * 3; ret = inflate(&s->zstream, Z_FINISH); if (ret == Z_DATA_ERROR) { av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n"); inflateSync(&s->zstream); ret = inflate(&s->zstream, Z_FINISH); } if (ret != Z_OK && ret != Z_STREAM_END) { av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret); /* return -1; */ } copy_region(s->tmpblock, s->frame.data[0], s->image_height - (hp + hs + 1), wp, hs, ws, s->frame.linesize[0]); skip_bits_long(&gb, 8 * size); /* skip the consumed bits */ } } } *data_size = sizeof(AVFrame); *(AVFrame*)data = s->frame; if ((get_bits_count(&gb) / 8) != buf_size) av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n", buf_size, (get_bits_count(&gb) / 8)); /* report that the buffer was completely consumed */ return buf_size; } static av_cold int flashsv_decode_end(AVCodecContext *avctx) { FlashSVContext *s = avctx->priv_data; inflateEnd(&s->zstream); /* release the frame if needed */ if (s->frame.data[0]) avctx->release_buffer(avctx, &s->frame); /* free the tmpblock */ av_free(s->tmpblock); return 0; } AVCodec ff_flashsv_decoder = { .name = "flashsv", .type = AVMEDIA_TYPE_VIDEO, .id = CODEC_ID_FLASHSV, .priv_data_size = sizeof(FlashSVContext), .init = flashsv_decode_init, .close = flashsv_decode_end, .decode = flashsv_decode_frame, .capabilities = CODEC_CAP_DR1, .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE}, .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"), };