added primitive image GIF encoder based on animated gif encoder

Originally committed as revision 1540 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/gif.c

@@ -166,45 +166,10 @@ static void gif_flush_put_bits_rev(PutBitContext *s)
 
 /* !RevPutBitContext */
 
-typedef struct {
-    UINT8 buffer[100]; /* data chunks */
-    INT64 time, file_time;
-} GIFContext;
-
-static int gif_write_header(AVFormatContext *s)
+/* GIF header */
+static int gif_image_write_header(ByteIOContext *pb, int width, int height)
 {
-    GIFContext *gif = s->priv_data;
-    ByteIOContext *pb = &s->pb;
-    AVCodecContext *enc, *video_enc;
-    int i, width, height, rate;
-
-/* XXX: do we reject audio streams or just ignore them ?
-    if(s->nb_streams > 1)
-        return -1;
-*/
-    gif->time = 0;
-    gif->file_time = 0;
-
-    video_enc = NULL;
-    for(i=0;i<s->nb_streams;i++) {
-        enc = &s->streams[i]->codec;
-        if (enc->codec_type != CODEC_TYPE_AUDIO)
-            video_enc = enc;
-    }
-
-    if (!video_enc) {
-        av_free(gif);
-        return -1;
-    } else {
-        width = video_enc->width;
-        height = video_enc->height;
-        rate = video_enc->frame_rate;
-    }
-
-    /* XXX: is it allowed ? seems to work so far... */
-    video_enc->pix_fmt = PIX_FMT_RGB24;
-
-    /* GIF header */
+    int i;
 
     put_tag(pb, "GIF");
     put_tag(pb, "89a");
@@ -233,8 +198,6 @@ static int gif_write_header(AVFormatContext *s)
     put_byte(pb, 0x00);
     put_byte(pb, 0x00);
 #endif
-
-    put_flush_packet(&s->pb);
     return 0;
 }
 
@@ -244,60 +207,28 @@ static inline unsigned char gif_clut_index(rgb_triplet *clut, UINT8 r, UINT8 g,
     return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
 }
 
-/* chunk writer callback */
-/* !!! XXX:deprecated
-static void gif_put_chunk(void *pbctx, UINT8 *buffer, int count)
-{
-    ByteIOContext *pb = (ByteIOContext *)pbctx;
-    put_byte(pb, (UINT8)count);
-    put_buffer(pb, buffer, count);
-}
-*/
 
-static int gif_write_video(AVFormatContext *s, 
-                           AVCodecContext *enc, UINT8 *buf, int size)
+static int gif_image_write_image(ByteIOContext *pb, 
+                                 int x1, int y1, int width, int height,
+                                 uint8_t *buf, int linesize)
 {
-    ByteIOContext *pb = &s->pb;
-    GIFContext *gif = s->priv_data;
-    int i, left, jiffies;
-    INT64 delay;
     PutBitContext p;
     UINT8 buffer[200]; /* 100 * 9 / 8 = 113 */
-
-
-    /* graphic control extension block */
-    put_byte(pb, 0x21);
-    put_byte(pb, 0xf9);
-    put_byte(pb, 0x04); /* block size */
-    put_byte(pb, 0x04); /* flags */
-    
-    /* 1 jiffy is 1/70 s */
-    /* the delay_time field indicates the number of jiffies - 1 */
-    delay = gif->file_time - gif->time;
-
-    /* XXX: should use delay, in order to be more accurate */
-    /* instead of using the same rounded value each time */
-    /* XXX: don't even remember if I really use it for now */
-    jiffies = (70*FRAME_RATE_BASE/enc->frame_rate) - 1;
-
-    put_le16(pb, jiffies);
-
-    put_byte(pb, 0x1f); /* transparent color index */
-    put_byte(pb, 0x00);
-
+    int i, left, w;
+    uint8_t *ptr;
     /* image block */
 
     put_byte(pb, 0x2c);
-    put_le16(pb, 0);
-    put_le16(pb, 0);
-    put_le16(pb, enc->width);
-    put_le16(pb, enc->height);
+    put_le16(pb, x1);
+    put_le16(pb, y1);
+    put_le16(pb, width);
+    put_le16(pb, height);
     put_byte(pb, 0x00); /* flags */
     /* no local clut */
 
     put_byte(pb, 0x08);
 
-    left=size/3;
+    left= width * height;
 
     init_put_bits(&p, buffer, 130, NULL, NULL);
 
@@ -305,14 +236,20 @@ static int gif_write_video(AVFormatContext *s,
  * the thing here is the bitstream is written as little packets, with a size byte before
  * but it's still the same bitstream between packets (no flush !)
  */
-
+    ptr = buf;
+    w = width;
     while(left>0) {
 
         gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
 
         for(i=0;i<GIF_CHUNKS;i++) {
-	    gif_put_bits_rev(&p, 9, gif_clut_index(NULL, *buf, buf[1], buf[2]));
-            buf+=3;
+	    gif_put_bits_rev(&p, 9, gif_clut_index(NULL, ptr[0], ptr[1], ptr[2]));
+            ptr+=3;
+            if (--w == 0) {
+                w = width;
+                buf += linesize;
+                ptr = buf;
+            }
         }
 
         if(left<=GIF_CHUNKS) {
@@ -331,6 +268,93 @@ static int gif_write_video(AVFormatContext *s,
 
         left-=GIF_CHUNKS;
     }
+    return 0;
+}
+
+typedef struct {
+    INT64 time, file_time;
+    UINT8 buffer[100]; /* data chunks */
+} GIFContext;
+
+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;
+
+/* XXX: do we reject audio streams or just ignore them ?
+    if(s->nb_streams > 1)
+        return -1;
+*/
+    gif->time = 0;
+    gif->file_time = 0;
+
+    video_enc = NULL;
+    for(i=0;i<s->nb_streams;i++) {
+        enc = &s->streams[i]->codec;
+        if (enc->codec_type != CODEC_TYPE_AUDIO)
+            video_enc = enc;
+    }
+
+    if (!video_enc) {
+        av_free(gif);
+        return -1;
+    } else {
+        width = video_enc->width;
+        height = video_enc->height;
+        rate = video_enc->frame_rate;
+    }
+
+    /* XXX: is it allowed ? seems to work so far... */
+    video_enc->pix_fmt = PIX_FMT_RGB24;
+
+    gif_image_write_header(pb, width, height);
+
+    put_flush_packet(&s->pb);
+    return 0;
+}
+
+/* chunk writer callback */
+/* !!! XXX:deprecated
+static void gif_put_chunk(void *pbctx, UINT8 *buffer, int count)
+{
+    ByteIOContext *pb = (ByteIOContext *)pbctx;
+    put_byte(pb, (UINT8)count);
+    put_buffer(pb, buffer, count);
+}
+*/
+
+static int gif_write_video(AVFormatContext *s, 
+                           AVCodecContext *enc, UINT8 *buf, int size)
+{
+    ByteIOContext *pb = &s->pb;
+    GIFContext *gif = s->priv_data;
+    int jiffies;
+    INT64 delay;
+
+    /* graphic control extension block */
+    put_byte(pb, 0x21);
+    put_byte(pb, 0xf9);
+    put_byte(pb, 0x04); /* block size */
+    put_byte(pb, 0x04); /* flags */
+    
+    /* 1 jiffy is 1/70 s */
+    /* the delay_time field indicates the number of jiffies - 1 */
+    delay = gif->file_time - gif->time;
+
+    /* XXX: should use delay, in order to be more accurate */
+    /* instead of using the same rounded value each time */
+    /* XXX: don't even remember if I really use it for now */
+    jiffies = (70*FRAME_RATE_BASE/enc->frame_rate) - 1;
+
+    put_le16(pb, jiffies);
+
+    put_byte(pb, 0x1f); /* transparent color index */
+    put_byte(pb, 0x00);
+
+    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
+                          buf, enc->width * 3);
 
     put_flush_packet(&s->pb);
     return 0;
@@ -355,6 +379,17 @@ static int gif_write_trailer(AVFormatContext *s)
     return 0;
 }
 
+/* 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_image(pb, 0, 0, info->width, info->height, 
+                          info->pict.data[0], info->pict.linesize[0]);
+    put_byte(pb, 0x3b);
+    put_flush_packet(pb);
+    return 0;
+}
+
 static AVOutputFormat gif_oformat = {
     "gif",
     "GIF Animation",
@@ -367,6 +402,7 @@ static AVOutputFormat gif_oformat = {
     gif_write_packet,
     gif_write_trailer,
 };
+
 extern AVInputFormat gif_iformat;
 
 int gif_init(void)