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author | Fabrice Bellard <fabrice@bellard.org> | 2003-02-02 19:16:51 +0000 |
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committer | Fabrice Bellard <fabrice@bellard.org> | 2003-02-02 19:16:51 +0000 |
commit | 12b64a225296e1c356a2bd69909abc541deb714c (patch) | |
tree | 093f44ca5217bc497505a13847ec6e4769dd7bdd /libavformat/gifdec.c | |
parent | a26058a50d3f9501701c4492dd78516509bc537d (diff) | |
download | ffmpeg-12b64a225296e1c356a2bd69909abc541deb714c.tar.gz |
added animated GIF decoder (pts and various disposal handling are missing)
Originally committed as revision 1533 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavformat/gifdec.c')
-rw-r--r-- | libavformat/gifdec.c | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/libavformat/gifdec.c b/libavformat/gifdec.c new file mode 100644 index 0000000000..63eb3408c6 --- /dev/null +++ b/libavformat/gifdec.c @@ -0,0 +1,466 @@ +/* + * GIF decoder + * Copyright (c) 2003 Fabrice Bellard. + * + * This library 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 of the License, or (at your option) any later version. + * + * This library 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 this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include "avformat.h" + +//#define DEBUG + +#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; + int image_count; + uint8_t *image_buf; + /* 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 */ + ByteIOContext *f; + 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 int gif_probe(AVProbeData * pd) +{ + if (pd->buf_size >= 24 && + (memcmp(pd->buf, gif87a_sig, 6) == 0 || + memcmp(pd->buf, gif89a_sig, 6) == 0)) + return AVPROBE_SCORE_MAX; + else + return 0; +} + +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 = get_byte(s->f); + s->ebuf = s->buf + sizbuf; + s->pbuf = s->buf; + if (sizbuf > 0) { + get_buffer(s->f, 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(AVFormatContext * s1, AVPacket * pkt) +{ + GifState *s = s1->priv_data; + int left, top, width, height, bits_per_pixel, code_size, flags; + int is_interleaved, has_local_palette, y, x, linesize; + ByteIOContext *f = &s1->pb; + uint8_t *ptr, *line, *d, *spal, *palette, *sptr; + + left = get_le16(f); + top = get_le16(f); + width = get_le16(f); + height = get_le16(f); + flags = get_byte(f); + 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) { + get_buffer(f, s->local_palette, 3 * (1 << bits_per_pixel)); + palette = s->local_palette; + } else { + palette = s->global_palette; + } + + /* allocate local image (XXX: horrible, needs API change) */ + if (s->image_count == 0) { + /* modify screen width/height if invalid */ + if (left + width > s->screen_width) + s->screen_width = left + width; + if (top + height > s->screen_height) + s->screen_width = top + height; + s->image_buf = av_malloc(s->screen_width * s->screen_height * 3); + if (!s->image_buf) + return -ENOMEM; + } else { + /* verify that all the image is inside the screen dimensions */ + if (left + width > s->screen_width || + top + height > s->screen_height) + return -EINVAL; + } + s->image_count++; + + line = av_malloc(width); + if (!line) + return -ENOMEM; + + /* now get the image data */ + s->f = f; + code_size = get_byte(f); + GLZWDecodeInit(s, code_size); + + /* read all the image and transcode it to RGB24 (horrible) */ + linesize = s->screen_width * 3; + ptr = s->image_buf + top * linesize + (left * 3); + for (y = 0; y < height; y++) { + GLZWDecode(s, line, width); + d = ptr; + sptr = line; + for(x = 0; x < width; x++) { + spal = palette + sptr[0] * 3; + d[0] = spal[0]; + d[1] = spal[1]; + d[2] = spal[2]; + d += 3; + sptr++; + } + ptr += linesize; + } + av_free(line); + + /* read the garbage data until end marker is found */ + while (!s->eob_reached) + GetCode(s); + + /* output image */ + /* XXX: avoid copying */ + if (av_new_packet(pkt, s->screen_width * s->screen_height * 3)) { + av_free(line); + return -EIO; + } + pkt->stream_index = 0; + memcpy(pkt->data, s->image_buf, s->screen_width * s->screen_height * 3); + return 0; +} + +static int gif_read_extension(AVFormatContext * s1) +{ + GifState *s = s1->priv_data; + ByteIOContext *f = &s1->pb; + int ext_code, ext_len, i, gce_flags, gce_transparent_index; + + /* extension */ + ext_code = get_byte(f); + ext_len = get_byte(f); +#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 = get_byte(f); + s->gce_delay = get_le16(f); + gce_transparent_index = get_byte(f); + 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 = get_byte(f); + break; + } + + /* NOTE: many extension blocks can come after */ + discard_ext: + while (ext_len != 0) { + for (i = 0; i < ext_len; i++) + get_byte(f); + ext_len = get_byte(f); +#ifdef DEBUG + printf("gif: ext_len1=%d\n", ext_len); +#endif + } + return 0; +} + +static int gif_read_header(AVFormatContext * s1, + AVFormatParameters * ap) +{ + GifState *s = s1->priv_data; + ByteIOContext *f = &s1->pb; + AVStream *st; + uint8_t sig[6]; + int ret, v, n; + int has_global_palette; + + /* read gif signature */ + ret = get_buffer(f, sig, 6); + if (ret != 6) + return -1; + 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 = get_le16(f); + s->screen_height = get_le16(f); + v = get_byte(f); + s->color_resolution = ((v & 0x70) >> 4) + 1; + has_global_palette = (v & 0x80); + s->bits_per_pixel = (v & 0x07) + 1; + s->background_color_index = get_byte(f); + get_byte(f); /* 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; + get_buffer(f, s->global_palette, n * 3); + } + /* now we are ready: build format streams */ + st = av_new_stream(s1, 0); + if (!st) + return -1; + + st->codec.codec_type = CODEC_TYPE_VIDEO; + st->codec.codec_id = CODEC_ID_RAWVIDEO; + st->codec.frame_rate = 5 * FRAME_RATE_BASE; + /* XXX: check if screen size is always valid */ + st->codec.width = s->screen_width; + st->codec.height = s->screen_height; + st->codec.pix_fmt = PIX_FMT_RGB24; + return 0; +} + +static int gif_read_packet(AVFormatContext * s1, + AVPacket * pkt) +{ + ByteIOContext *f = &s1->pb; + int ret, code; + + for (;;) { + code = url_fgetc(f); +#ifdef DEBUG + printf("gif: code=%02x '%c'\n", code, code); +#endif + switch (code) { + case ',': + if (gif_read_image(s1, pkt) < 0) + return -EIO; + ret = 0; + goto the_end; + case ';': + /* end of image */ + ret = -EIO; + goto the_end; + case '!': + if (gif_read_extension(s1) < 0) + return -EIO; + break; + case EOF: + default: + /* error or errneous EOF */ + ret = -EIO; + goto the_end; + } + } + the_end: + return ret; +} + +static int gif_read_close(AVFormatContext *s1) +{ + GifState *s = s1->priv_data; + av_free(s->image_buf); + return 0; +} + +AVInputFormat gif_iformat = +{ + "gif", + "gif format", + sizeof(GifState), + gif_probe, + gif_read_header, + gif_read_packet, + gif_read_close, +}; |