X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavformat%2Fgifdec.c;h=c20bde178191067f574144377a07af751a429bac;hb=bc70684e74a185d7b80c8b80bdedda659cb581b8;hp=8993ca615c054b1e1973055b5743f9bde5b2af11;hpb=b14761d1f8372dfe558193b8b754b9f1a858077d;p=ffmpeg

diff --git a/libavformat/gifdec.c b/libavformat/gifdec.c
index 8993ca615c0..c20bde17819 100644
--- a/libavformat/gifdec.c
+++ b/libavformat/gifdec.c
@@ -25,6 +25,7 @@
  */
 
 #include "avformat.h"
+#include "libavutil/bprint.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"
 #include "internal.h"
@@ -68,7 +69,7 @@ typedef struct GIFDemuxContext {
  */
 #define GIF_MIN_DELAY       2
 
-static int gif_probe(AVProbeData *p)
+static int gif_probe(const AVProbeData *p)
 {
     /* check magick */
     if (memcmp(p->buf, gif87a_sig, 6) && memcmp(p->buf, gif89a_sig, 6))
@@ -94,12 +95,25 @@ static int resync(AVIOContext *pb)
     return 0;
 }
 
+static int gif_skip_subblocks(AVIOContext *pb)
+{
+    int sb_size, ret = 0;
+
+    while (0x00 != (sb_size = avio_r8(pb))) {
+        if ((ret = avio_skip(pb, sb_size)) < 0)
+            return ret;
+    }
+
+    return ret;
+}
+
 static int gif_read_header(AVFormatContext *s)
 {
     GIFDemuxContext *gdc = s->priv_data;
     AVIOContext     *pb  = s->pb;
     AVStream        *st;
-    int width, height, ret;
+    int type, width, height, ret, n, flags;
+    int64_t nb_frames = 0, duration = 0;
 
     if ((ret = resync(pb)) < 0)
         return ret;
@@ -107,6 +121,9 @@ static int gif_read_header(AVFormatContext *s)
     gdc->delay  = gdc->default_delay;
     width  = avio_rl16(pb);
     height = avio_rl16(pb);
+    flags = avio_r8(pb);
+    avio_skip(pb, 1);
+    n      = avio_r8(pb);
 
     if (width == 0 || height == 0)
         return AVERROR_INVALIDDATA;
@@ -115,6 +132,57 @@ static int gif_read_header(AVFormatContext *s)
     if (!st)
         return AVERROR(ENOMEM);
 
+    if (flags & 0x80)
+        avio_skip(pb, 3 * (1 << ((flags & 0x07) + 1)));
+
+    while ((type = avio_r8(pb)) != GIF_TRAILER) {
+        if (avio_feof(pb))
+            break;
+        if (type == GIF_EXTENSION_INTRODUCER) {
+            int subtype = avio_r8(pb);
+            if (subtype == GIF_COM_EXT_LABEL) {
+                AVBPrint bp;
+                int block_size;
+
+                av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
+                while ((block_size = avio_r8(pb)) != 0) {
+                    avio_read_to_bprint(pb, &bp, block_size);
+                }
+                av_dict_set(&s->metadata, "comment", bp.str, 0);
+                av_bprint_finalize(&bp, NULL);
+            } else if (subtype == GIF_GCE_EXT_LABEL) {
+                int block_size = avio_r8(pb);
+
+                if (block_size == 4) {
+                    int delay;
+
+                    avio_skip(pb, 1);
+                    delay = avio_rl16(pb);
+                    if (delay < gdc->min_delay)
+                        delay = gdc->default_delay;
+                    delay = FFMIN(delay, gdc->max_delay);
+                    duration += delay;
+                    avio_skip(pb, 1);
+                } else {
+                    avio_skip(pb, block_size);
+                }
+                gif_skip_subblocks(pb);
+            } else {
+                gif_skip_subblocks(pb);
+            }
+        } else if (type == GIF_IMAGE_SEPARATOR) {
+            avio_skip(pb, 8);
+            flags = avio_r8(pb);
+            if (flags & 0x80)
+                avio_skip(pb, 3 * (1 << ((flags & 0x07) + 1)));
+            avio_skip(pb, 1);
+            gif_skip_subblocks(pb);
+            nb_frames++;
+        } else {
+            break;
+        }
+    }
+
     /* GIF format operates with time in "hundredths of second",
      * therefore timebase is 1/100 */
     avpriv_set_pts_info(st, 64, 1, 100);
@@ -122,6 +190,13 @@ static int gif_read_header(AVFormatContext *s)
     st->codecpar->codec_id   = AV_CODEC_ID_GIF;
     st->codecpar->width      = width;
     st->codecpar->height     = height;
+    st->start_time           = 0;
+    st->duration             = duration;
+    st->nb_frames            = nb_frames;
+    if (n) {
+        st->codecpar->sample_aspect_ratio.num = n + 15;
+        st->codecpar->sample_aspect_ratio.den = 64;
+    }
 
     /* jump to start because gif decoder needs header data too */
     if (avio_seek(pb, 0, SEEK_SET) != 0)
@@ -130,18 +205,6 @@ static int gif_read_header(AVFormatContext *s)
     return 0;
 }
 
-static int gif_skip_subblocks(AVIOContext *pb)
-{
-    int sb_size, ret = 0;
-
-    while (0x00 != (sb_size = avio_r8(pb))) {
-        if ((ret = avio_skip(pb, sb_size)) < 0)
-            return ret;
-    }
-
-    return ret;
-}
-
 static int gif_read_ext(AVFormatContext *s)
 {
     GIFDemuxContext *gdc = s->priv_data;
@@ -334,7 +397,7 @@ static const AVClass demuxer_class = {
     .category   = AV_CLASS_CATEGORY_DEMUXER,
 };
 
-AVInputFormat ff_gif_demuxer = {
+const AVInputFormat ff_gif_demuxer = {
     .name           = "gif",
     .long_name      = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
     .priv_data_size = sizeof(GIFDemuxContext),