diff options
author | Baptiste Coudurier <baptiste.coudurier@gmail.com> | 2006-10-22 19:05:03 +0400 |
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committer | Baptiste Coudurier <baptiste.coudurier@gmail.com> | 2006-10-22 19:05:03 +0400 |
commit | 06d392a7cc93dcab84c225d7e8cb7030d537581f (patch) | |
tree | cf0e34b35809d71976cd3036ffab3b8a3b233082 /libavcodec/gifdec.c | |
parent | b92f5a6b31c8c08b08f84dccd89c1cfa98695444 (diff) |
change gif demuxer to gif decoder
Originally committed as revision 6760 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/gifdec.c')
-rw-r--r-- | libavcodec/gifdec.c | 495 |
1 files changed, 495 insertions, 0 deletions
diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c new file mode 100644 index 0000000000..4b92447258 --- /dev/null +++ b/libavcodec/gifdec.c @@ -0,0 +1,495 @@ +/* + * GIF decoder + * Copyright (c) 2003 Fabrice Bellard. + * Copyright (c) 2006 Baptiste Coudurier. + * + * 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 DEBUG + +#include "avcodec.h" +#include "bytestream.h" + +#define MAXBITS 12 +#define SIZTABLE (1<<MAXBITS) + +#define GCE_DISPOSAL_NONE 0 +#define GCE_DISPOSAL_INPLACE 1 +#define GCE_DISPOSAL_BACKGROUND 2 +#define GCE_DISPOSAL_RESTORE 3 + +typedef struct GifState { + int screen_width; + int screen_height; + int bits_per_pixel; + int background_color_index; + int transparent_color_index; + int color_resolution; + uint8_t *image_buf; + int image_linesize; + uint32_t image_palette[256]; + int pix_fmt; + + /* after the frame is displayed, the disposal method is used */ + int gce_disposal; + /* delay during which the frame is shown */ + int gce_delay; + + /* LZW compatible decoder */ + uint8_t *bytestream; + int eob_reached; + uint8_t *pbuf, *ebuf; + int bbits; + unsigned int bbuf; + + int cursize; /* The current code size */ + int curmask; + int codesize; + int clear_code; + int end_code; + int newcodes; /* First available code */ + int top_slot; /* Highest code for current size */ + int slot; /* Last read code */ + int fc, oc; + uint8_t *sp; + uint8_t stack[SIZTABLE]; + uint8_t suffix[SIZTABLE]; + uint16_t prefix[SIZTABLE]; + + /* aux buffers */ + uint8_t global_palette[256 * 3]; + uint8_t local_palette[256 * 3]; + uint8_t buf[256]; +} GifState; + +static const uint8_t gif87a_sig[6] = "GIF87a"; +static const uint8_t gif89a_sig[6] = "GIF89a"; + +static const uint16_t mask[17] = +{ + 0x0000, 0x0001, 0x0003, 0x0007, + 0x000F, 0x001F, 0x003F, 0x007F, + 0x00FF, 0x01FF, 0x03FF, 0x07FF, + 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF +}; + +static void GLZWDecodeInit(GifState * s, int csize) +{ + /* read buffer */ + s->eob_reached = 0; + s->pbuf = s->buf; + s->ebuf = s->buf; + s->bbuf = 0; + s->bbits = 0; + + /* decoder */ + s->codesize = csize; + s->cursize = s->codesize + 1; + s->curmask = mask[s->cursize]; + s->top_slot = 1 << s->cursize; + s->clear_code = 1 << s->codesize; + s->end_code = s->clear_code + 1; + s->slot = s->newcodes = s->clear_code + 2; + s->oc = s->fc = 0; + s->sp = s->stack; +} + +/* XXX: optimize */ +static inline int GetCode(GifState * s) +{ + int c, sizbuf; + uint8_t *ptr; + + while (s->bbits < s->cursize) { + ptr = s->pbuf; + if (ptr >= s->ebuf) { + if (!s->eob_reached) { + sizbuf = bytestream_get_byte(&s->bytestream); + s->ebuf = s->buf + sizbuf; + s->pbuf = s->buf; + if (sizbuf > 0) { + bytestream_get_buffer(&s->bytestream, s->buf, sizbuf); + } else { + s->eob_reached = 1; + } + } + ptr = s->pbuf; + } + s->bbuf |= ptr[0] << s->bbits; + ptr++; + s->pbuf = ptr; + s->bbits += 8; + } + c = s->bbuf & s->curmask; + s->bbuf >>= s->cursize; + s->bbits -= s->cursize; + return c; +} + +/* NOTE: the algorithm here is inspired from the LZW GIF decoder + written by Steven A. Bennett in 1987. */ +/* return the number of byte decoded */ +static int GLZWDecode(GifState * s, uint8_t * buf, int len) +{ + int l, c, code, oc, fc; + uint8_t *sp; + + if (s->end_code < 0) + return 0; + + l = len; + sp = s->sp; + oc = s->oc; + fc = s->fc; + + while (sp > s->stack) { + *buf++ = *(--sp); + if ((--l) == 0) + goto the_end; + } + + for (;;) { + c = GetCode(s); + if (c == s->end_code) { + s->end_code = -1; + break; + } else if (c == s->clear_code) { + s->cursize = s->codesize + 1; + s->curmask = mask[s->cursize]; + s->slot = s->newcodes; + s->top_slot = 1 << s->cursize; + while ((c = GetCode(s)) == s->clear_code); + if (c == s->end_code) { + s->end_code = -1; + break; + } + /* test error */ + if (c >= s->slot) + c = 0; + fc = oc = c; + *buf++ = c; + if ((--l) == 0) + break; + } else { + code = c; + if (code >= s->slot) { + *sp++ = fc; + code = oc; + } + while (code >= s->newcodes) { + *sp++ = s->suffix[code]; + code = s->prefix[code]; + } + *sp++ = code; + if (s->slot < s->top_slot) { + s->suffix[s->slot] = fc = code; + s->prefix[s->slot++] = oc; + oc = c; + } + if (s->slot >= s->top_slot) { + if (s->cursize < MAXBITS) { + s->top_slot <<= 1; + s->curmask = mask[++s->cursize]; + } + } + while (sp > s->stack) { + *buf++ = *(--sp); + if ((--l) == 0) + goto the_end; + } + } + } + the_end: + s->sp = sp; + s->oc = oc; + s->fc = fc; + return len - l; +} + +static int gif_read_image(GifState *s) +{ + int left, top, width, height, bits_per_pixel, code_size, flags; + int is_interleaved, has_local_palette, y, x, pass, y1, linesize, n, i; + uint8_t *ptr, *line, *d, *spal, *palette, *sptr, *ptr1; + + left = bytestream_get_le16(&s->bytestream); + top = bytestream_get_le16(&s->bytestream); + width = bytestream_get_le16(&s->bytestream); + height = bytestream_get_le16(&s->bytestream); + flags = bytestream_get_byte(&s->bytestream); + is_interleaved = flags & 0x40; + has_local_palette = flags & 0x80; + bits_per_pixel = (flags & 0x07) + 1; +#ifdef DEBUG + printf("gif: image x=%d y=%d w=%d h=%d\n", left, top, width, height); +#endif + + if (has_local_palette) { + bytestream_get_buffer(&s->bytestream, s->local_palette, 3 * (1 << bits_per_pixel)); + palette = s->local_palette; + } else { + palette = s->global_palette; + bits_per_pixel = s->bits_per_pixel; + } + + /* verify that all the image is inside the screen dimensions */ + if (left + width > s->screen_width || + top + height > s->screen_height) + return -EINVAL; + + /* build the palette */ + n = (1 << bits_per_pixel); + spal = palette; + for(i = 0; i < n; i++) { + s->image_palette[i] = (0xff << 24) | + (spal[0] << 16) | (spal[1] << 8) | (spal[2]); + spal += 3; + } + for(; i < 256; i++) + s->image_palette[i] = (0xff << 24); + /* handle transparency */ + if (s->transparent_color_index >= 0) + s->image_palette[s->transparent_color_index] = 0; + line = NULL; + + /* now get the image data */ + code_size = bytestream_get_byte(&s->bytestream); + GLZWDecodeInit(s, code_size); + + /* read all the image */ + linesize = s->image_linesize; + ptr1 = s->image_buf + top * linesize + (left * 3); + ptr = ptr1; + pass = 0; + y1 = 0; + for (y = 0; y < height; y++) { + GLZWDecode(s, ptr, width); + if (is_interleaved) { + switch(pass) { + default: + case 0: + case 1: + y1 += 8; + ptr += linesize * 8; + if (y1 >= height) { + y1 = 4; + if (pass == 0) + ptr = ptr1 + linesize * 4; + else + ptr = ptr1 + linesize * 2; + pass++; + } + break; + case 2: + y1 += 4; + ptr += linesize * 4; + if (y1 >= height) { + y1 = 1; + ptr = ptr1 + linesize; + pass++; + } + break; + case 3: + y1 += 2; + ptr += linesize * 2; + break; + } + } else { + ptr += linesize; + } + } + av_free(line); + + /* read the garbage data until end marker is found */ + while (!s->eob_reached) + GetCode(s); + return 0; +} + +static int gif_read_extension(GifState *s) +{ + int ext_code, ext_len, i, gce_flags, gce_transparent_index; + + /* extension */ + ext_code = bytestream_get_byte(&s->bytestream); + ext_len = bytestream_get_byte(&s->bytestream); +#ifdef DEBUG + printf("gif: ext_code=0x%x len=%d\n", ext_code, ext_len); +#endif + switch(ext_code) { + case 0xf9: + if (ext_len != 4) + goto discard_ext; + s->transparent_color_index = -1; + gce_flags = bytestream_get_byte(&s->bytestream); + s->gce_delay = bytestream_get_le16(&s->bytestream); + gce_transparent_index = bytestream_get_byte(&s->bytestream); + if (gce_flags & 0x01) + s->transparent_color_index = gce_transparent_index; + else + s->transparent_color_index = -1; + s->gce_disposal = (gce_flags >> 2) & 0x7; +#ifdef DEBUG + printf("gif: gce_flags=%x delay=%d tcolor=%d disposal=%d\n", + gce_flags, s->gce_delay, + s->transparent_color_index, s->gce_disposal); +#endif + ext_len = bytestream_get_byte(&s->bytestream); + break; + } + + /* NOTE: many extension blocks can come after */ + discard_ext: + while (ext_len != 0) { + for (i = 0; i < ext_len; i++) + bytestream_get_byte(&s->bytestream); + ext_len = bytestream_get_byte(&s->bytestream); +#ifdef DEBUG + printf("gif: ext_len1=%d\n", ext_len); +#endif + } + return 0; +} + +static int gif_read_header1(GifState *s) +{ + uint8_t sig[6]; + int ret, v, n; + int has_global_palette; + + /* read gif signature */ + bytestream_get_buffer(&s->bytestream, sig, 6); + if (memcmp(sig, gif87a_sig, 6) != 0 && + memcmp(sig, gif89a_sig, 6) != 0) + return -1; + + /* read screen header */ + s->transparent_color_index = -1; + s->screen_width = bytestream_get_le16(&s->bytestream); + s->screen_height = bytestream_get_le16(&s->bytestream); + if( (unsigned)s->screen_width > 32767 + || (unsigned)s->screen_height > 32767){ + av_log(NULL, AV_LOG_ERROR, "picture size too large\n"); + return -1; + } + + v = bytestream_get_byte(&s->bytestream); + s->color_resolution = ((v & 0x70) >> 4) + 1; + has_global_palette = (v & 0x80); + s->bits_per_pixel = (v & 0x07) + 1; + s->background_color_index = bytestream_get_byte(&s->bytestream); + bytestream_get_byte(&s->bytestream); /* ignored */ +#ifdef DEBUG + printf("gif: screen_w=%d screen_h=%d bpp=%d global_palette=%d\n", + s->screen_width, s->screen_height, s->bits_per_pixel, + has_global_palette); +#endif + if (has_global_palette) { + n = 1 << s->bits_per_pixel; + bytestream_get_buffer(&s->bytestream, s->global_palette, n * 3); + } + return 0; +} + +static int gif_parse_next_image(GifState *s) +{ + int ret, code; + + for (;;) { + code = bytestream_get_byte(&s->bytestream); +#ifdef DEBUG + printf("gif: code=%02x '%c'\n", code, code); +#endif + switch (code) { + case ',': + if (gif_read_image(s) < 0) + return -1; + ret = 0; + goto the_end; + case ';': + /* end of image */ + ret = -1; + goto the_end; + case '!': + if (gif_read_extension(s) < 0) + return -1; + break; + case EOF: + default: + /* error or errneous EOF */ + ret = -1; + goto the_end; + } + } + the_end: + return ret; +} + +static int gif_decode_init(AVCodecContext *avctx) +{ + GifState *s = avctx->priv_data; + + return 0; +} + +static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size) +{ + GifState *s = avctx->priv_data; + AVFrame *picture = data; + int ret; + + s->bytestream = buf; + if (gif_read_header1(s) < 0) + return -1; + + /* allocate image buffer */ + s->image_linesize = s->screen_width * 3; + s->image_buf = av_malloc(s->screen_height * s->image_linesize); + if (!s->image_buf) + return -ENOMEM; + s->pix_fmt = PIX_FMT_PAL8; + /* now we are ready: build format streams */ + + /* XXX: check if screen size is always valid */ + avctx->width = s->screen_width; + avctx->height = s->screen_height; + avctx->pix_fmt = PIX_FMT_PAL8; + + ret = gif_parse_next_image(s); + if (ret < 0) + return ret; + + picture->data[0] = s->image_buf; + picture->linesize[0] = s->image_linesize; + picture->data[1] = s->image_palette; + picture->linesize[1] = 4; + + *data_size = sizeof(AVPicture); + return 0; +} + +AVCodec gif_decoder = { + "gif", + CODEC_TYPE_VIDEO, + CODEC_ID_GIF, + sizeof(GifState), + gif_decode_init, + NULL, + NULL, + gif_decode_frame, +}; |