--- /dev/null
+/*
+ * 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"
+
+int gif_write(ByteIOContext *pb, AVImageInfo *info);
+
+//#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;
+ uint8_t *image_buf;
+ int image_linesize;
+ uint32_t *image_palette;
+ 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 */
+ 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
+};
+
+/* Probe gif video format or gif image format. The current heuristic
+ supposes the gif87a is always a single image. For gif89a, we
+ consider it as a video only if a GCE extension is present in the
+ first kilobyte. */
+static int gif_video_probe(AVProbeData * pd)
+{
+ const uint8_t *p, *p_end;
+ int bits_per_pixel, has_global_palette, ext_code, ext_len;
+ int gce_flags, gce_disposal;
+
+ if (pd->buf_size < 24 ||
+ memcmp(pd->buf, gif89a_sig, 6) != 0)
+ return 0;
+ p_end = pd->buf + pd->buf_size;
+ p = pd->buf + 6;
+ bits_per_pixel = (p[4] & 0x07) + 1;
+ has_global_palette = (p[4] & 0x80);
+ p += 7;
+ if (has_global_palette)
+ p += (1 << bits_per_pixel) * 3;
+ for(;;) {
+ if (p >= p_end)
+ return 0;
+ if (*p != '!')
+ break;
+ p++;
+ if (p >= p_end)
+ return 0;
+ ext_code = *p++;
+ if (p >= p_end)
+ return 0;
+ ext_len = *p++;
+ if (ext_code == 0xf9) {
+ if (p >= p_end)
+ return 0;
+ /* if GCE extension found with gce_disposal != 0: it is
+ likely to be an animation */
+ gce_flags = *p++;
+ gce_disposal = (gce_flags >> 2) & 0x7;
+ if (gce_disposal != 0)
+ return AVPROBE_SCORE_MAX;
+ else
+ return 0;
+ }
+ for(;;) {
+ if (ext_len == 0)
+ break;
+ p += ext_len;
+ if (p >= p_end)
+ return 0;
+ ext_len = *p++;
+ }
+ }
+ return 0;
+}
+
+static int gif_image_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 - 1;
+ 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(GifState *s)
+{
+ ByteIOContext *f = s->f;
+ 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 = 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;
+ 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 */
+ if (s->pix_fmt == PIX_FMT_RGB24) {
+ line = av_malloc(width);
+ if (!line)
+ return -ENOMEM;
+ } else {
+ 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 */
+ s->f = f;
+ code_size = get_byte(f);
+ 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++) {
+ if (s->pix_fmt == PIX_FMT_RGB24) {
+ /* transcode to RGB24 */
+ 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++;
+ }
+ } else {
+ 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)
+{
+ ByteIOContext *f = s->f;
+ 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_header1(GifState *s)
+{
+ ByteIOContext *f = s->f;
+ 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);
+ }
+ return 0;
+}
+
+static int gif_parse_next_image(GifState *s)
+{
+ ByteIOContext *f = s->f;
+ 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(s) < 0)
+ return -EIO;
+ ret = 0;
+ goto the_end;
+ case ';':
+ /* end of image */
+ ret = -EIO;
+ goto the_end;
+ case '!':
+ if (gif_read_extension(s) < 0)
+ return -EIO;
+ break;
+ case EOF:
+ default:
+ /* error or errneous EOF */
+ ret = -EIO;
+ goto the_end;
+ }
+ }
+ the_end:
+ return ret;
+}
+
+static int gif_read_header(AVFormatContext * s1,
+ AVFormatParameters * ap)
+{
+ GifState *s = s1->priv_data;
+ ByteIOContext *f = &s1->pb;
+ AVStream *st;
+
+ s->f = f;
+ 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_RGB24;
+ /* 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;
+ st->codec.frame_rate_base = 1;
+ /* 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)
+{
+ GifState *s = s1->priv_data;
+ int ret;
+
+ ret = gif_parse_next_image(s);
+ if (ret < 0)
+ return ret;
+
+ /* XXX: avoid copying */
+ if (av_new_packet(pkt, s->screen_width * s->screen_height * 3)) {
+ 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_close(AVFormatContext *s1)
+{
+ GifState *s = s1->priv_data;
+ av_free(s->image_buf);
+ return 0;
+}
+
+/* read gif as image */
+static int gif_read(ByteIOContext *f,
+ int (*alloc_cb)(void *opaque, AVImageInfo *info), void *opaque)
+{
+ GifState s1, *s = &s1;
+ AVImageInfo info1, *info = &info1;
+ int ret;
+
+ memset(s, 0, sizeof(GifState));
+ s->f = f;
+ if (gif_read_header1(s) < 0)
+ return -1;
+ info->width = s->screen_width;
+ info->height = s->screen_height;
+ info->pix_fmt = PIX_FMT_PAL8;
+ ret = alloc_cb(opaque, info);
+ if (ret)
+ return ret;
+ s->image_buf = info->pict.data[0];
+ s->image_linesize = info->pict.linesize[0];
+ s->image_palette = (uint32_t *)info->pict.data[1];
+
+ if (gif_parse_next_image(s) < 0)
+ return -1;
+ return 0;
+}
+
+AVInputFormat gif_iformat =
+{
+ "gif",
+ "gif format",
+ sizeof(GifState),
+ gif_video_probe,
+ gif_read_header,
+ gif_read_packet,
+ gif_read_close,
+};
+
+AVImageFormat gif_image_format = {
+ "gif",
+ "gif",
+ gif_image_probe,
+ gif_read,
+ (1 << PIX_FMT_PAL8),
+ gif_write,
+};
projects / synfig.git / blobdiff