When BitsPerSample tag is not present in TIFF, that means file is

monochrome, so initialize picture before decoding.
This fixes decoding monochrome files produced by lavc TIFF encoder.

Originally committed as revision 20091 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/tiff.c

@@ -498,9 +498,20 @@ static int decode_frame(AVCodecContext *avctx,
     }
     /* now we have the data and may start decoding */
     if(!p->data[0]){
-        av_log(s->avctx, AV_LOG_ERROR, "Picture initialization missing\n");
+        s->bpp = 1;
+        avctx->pix_fmt = PIX_FMT_MONOBLACK;
+        if(s->width != s->avctx->width || s->height != s->avctx->height){
+            if(avcodec_check_dimensions(s->avctx, s->width, s->height))
+                return -1;
+            avcodec_set_dimensions(s->avctx, s->width, s->height);
+        }
+        if(s->picture.data[0])
+            s->avctx->release_buffer(s->avctx, &s->picture);
+        if(s->avctx->get_buffer(s->avctx, &s->picture) < 0){
+            av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }
+    }
     if(s->strips == 1 && !s->stripsize){
         av_log(avctx, AV_LOG_WARNING, "Image data size missing\n");
         s->stripsize = buf_size - s->stripoff;