added animated GIF decoder (pts and various disposal handling are missing)

Originally committed as revision 1533 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/gif.c

@@ -367,9 +367,11 @@ static AVOutputFormat gif_oformat = {
     gif_write_packet,
     gif_write_trailer,
 };
+extern AVInputFormat gif_iformat;
 
 int gif_init(void)
 {
     av_register_output_format(&gif_oformat);
+    av_register_input_format(&gif_iformat);
     return 0;
 }

libavformat/gifdec.c

+/*
+ * 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,
+};