aboutsummaryrefslogtreecommitdiffstats
path: root/libavformat/gif.c
diff options
context:
space:
mode:
authorTodd Kirby <doubleshot@pacbell.net>2005-06-18 01:52:24 +0000
committerMichael Niedermayer <michaelni@gmx.at>2005-06-18 01:52:24 +0000
commit8108551a5c4c4c9696582c73d000f94b12cd95a5 (patch)
tree2ec75876931d8d935492d183fbcac69db2fbe64d /libavformat/gif.c
parentbb628dae442f85fc8814d7c60c744a409fa001ab (diff)
downloadffmpeg-8108551a5c4c4c9696582c73d000f94b12cd95a5.tar.gz
Animated GIF looping patch by (Todd Kirby // ffmpeg.php gmail com)
Originally committed as revision 4383 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavformat/gif.c')
-rw-r--r--libavformat/gif.c47
1 files changed, 35 insertions, 12 deletions
diff --git a/libavformat/gif.c b/libavformat/gif.c
index 0cb9b9a1ee..1248139d79 100644
--- a/libavformat/gif.c
+++ b/libavformat/gif.c
@@ -43,8 +43,9 @@
/* bitstream minipacket size */
#define GIF_CHUNKS 100
-/* slows down the decoding (and some browsers doesn't like it) */
-/* #define GIF_ADD_APP_HEADER */
+/* slows down the decoding (and some browsers don't like it) */
+/* update on the 'some browsers don't like it issue from above: this was probably due to missing 'Data Sub-block Terminator' (byte 19) in the app_header */
+#define GIF_ADD_APP_HEADER // required to enable looping of animated gif
typedef struct {
unsigned char r;
@@ -169,7 +170,8 @@ static void gif_flush_put_bits_rev(PutBitContext *s)
/* GIF header */
static int gif_image_write_header(ByteIOContext *pb,
- int width, int height, uint32_t *palette)
+ int width, int height, int loop_count,
+ uint32_t *palette)
{
int i;
unsigned int v;
@@ -197,17 +199,37 @@ static int gif_image_write_header(ByteIOContext *pb,
}
}
+ /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
+ see http://members.aol.com/royalef/gifabout.htm#net-extension
+
+ byte 1 : 33 (hex 0x21) GIF Extension code
+ byte 2 : 255 (hex 0xFF) Application Extension Label
+ byte 3 : 11 (hex (0x0B) Length of Application Block
+ (eleven bytes of data to follow)
+ bytes 4 to 11 : "NETSCAPE"
+ bytes 12 to 14 : "2.0"
+ byte 15 : 3 (hex 0x03) Length of Data Sub-Block
+ (three bytes of data to follow)
+ byte 16 : 1 (hex 0x01)
+ bytes 17 to 18 : 0 to 65535, an unsigned integer in
+ lo-hi byte format. This indicate the
+ number of iterations the loop should
+ be executed.
+ bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator
+ */
+
/* application extension header */
- /* XXX: not really sure what to put in here... */
#ifdef GIF_ADD_APP_HEADER
+ if (loop_count >= 0 && loop_count <= 65535) {
put_byte(pb, 0x21);
put_byte(pb, 0xff);
put_byte(pb, 0x0b);
- put_tag(pb, "NETSCAPE2.0");
- put_byte(pb, 0x03);
- put_byte(pb, 0x01);
- put_byte(pb, 0x00);
- put_byte(pb, 0x00);
+ put_tag(pb, "NETSCAPE2.0"); // bytes 4 to 14
+ put_byte(pb, 0x03); // byte 15
+ put_byte(pb, 0x01); // byte 16
+ put_le16(pb, (uint16_t)loop_count);
+ put_byte(pb, 0x00); // byte 19
+ }
#endif
return 0;
}
@@ -294,7 +316,7 @@ static int gif_write_header(AVFormatContext *s)
GIFContext *gif = s->priv_data;
ByteIOContext *pb = &s->pb;
AVCodecContext *enc, *video_enc;
- int i, width, height/*, rate*/;
+ int i, width, height, loop_count /*, rate*/;
/* XXX: do we reject audio streams or just ignore them ?
if(s->nb_streams > 1)
@@ -316,13 +338,14 @@ static int gif_write_header(AVFormatContext *s)
} else {
width = video_enc->width;
height = video_enc->height;
+ loop_count = s->loop_output;
// rate = video_enc->time_base.den;
}
/* XXX: is it allowed ? seems to work so far... */
video_enc->pix_fmt = PIX_FMT_RGB24;
- gif_image_write_header(pb, width, height, NULL);
+ gif_image_write_header(pb, width, height, loop_count, NULL);
put_flush_packet(&s->pb);
return 0;
@@ -384,7 +407,7 @@ static int gif_write_trailer(AVFormatContext *s)
/* better than nothing gif image writer */
int gif_write(ByteIOContext *pb, AVImageInfo *info)
{
- gif_image_write_header(pb, info->width, info->height,
+ gif_image_write_header(pb, info->width, info->height, AVFMT_NOOUTPUTLOOP,
(uint32_t *)info->pict.data[1]);
gif_image_write_image(pb, 0, 0, info->width, info->height,
info->pict.data[0], info->pict.linesize[0],