avcodec/mjpegdec: Do not try to detect last scan but apply idct after all scans for progressive jpeg

Fixes: IMG-20160418-WA0002.jpg

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/mjpegdec.c

@@ -1375,11 +1375,7 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
     int mb_x, mb_y;
     int EOBRUN = 0;
     int c = s->comp_index[0];
-    uint8_t *data = s->picture_ptr->data[c];
-    int linesize  = s->linesize[c];
-    int last_scan = 0;
     int16_t *quant_matrix = s->quant_matrixes[s->quant_sindex[0]];
-    int bytes_per_pixel = 1 + (s->bits > 8);
 
     av_assert0(ss>=0 && Ah>=0 && Al>=0);
     if (se < ss || se > 63) {
@@ -1390,15 +1386,10 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
     // s->coefs_finished is a bitmask for coefficients coded
     // ss and se are parameters telling start and end coefficients
     s->coefs_finished[c] |= (2ULL << se) - (1ULL << ss);
-    last_scan = !Al && !~s->coefs_finished[c];
-
-    if (s->interlaced && s->bottom_field)
-        data += linesize >> 1;
 
     s->restart_count = 0;
 
     for (mb_y = 0; mb_y < s->mb_height; mb_y++) {
-        uint8_t *ptr     = data + (mb_y * linesize * 8 >> s->avctx->lowres);
         int block_idx    = mb_y * s->block_stride[c];
         int16_t (*block)[64] = &s->blocks[c][block_idx];
         uint8_t *last_nnz    = &s->last_nnz[c][block_idx];
@@ -1419,12 +1410,6 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
                     return AVERROR_INVALIDDATA;
                 }
 
-            if (last_scan) {
-                    s->idsp.idct_put(ptr, linesize, *block);
-                    if (s->bits & 7)
-                        shift_output(s, ptr, linesize);
-                    ptr += bytes_per_pixel*8 >> s->avctx->lowres;
-            }
             if (handle_rstn(s, 0))
                 EOBRUN = 0;
         }
@@ -1432,6 +1417,41 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
     return 0;
 }
 
+static void mjpeg_idct_scan_progressive_ac(MJpegDecodeContext *s)
+{
+    int mb_x, mb_y;
+    int c;
+    const int bytes_per_pixel = 1 + (s->bits > 8);
+    const int block_size = s->lossless ? 1 : 8;
+
+    for (c = 0; c < s->nb_components; c++) {
+        uint8_t *data = s->picture_ptr->data[c];
+        int linesize  = s->linesize[c];
+        int h = s->h_max / s->h_count[c];
+        int v = s->v_max / s->v_count[c];
+        int mb_width     = (s->width  + h * block_size - 1) / (h * block_size);
+        int mb_height    = (s->height + v * block_size - 1) / (v * block_size);
+
+        if (~s->coefs_finished[c])
+            av_log(s->avctx, AV_LOG_WARNING, "component %d is incomplete\n", c);
+
+        if (s->interlaced && s->bottom_field)
+            data += linesize >> 1;
+
+        for (mb_y = 0; mb_y < mb_height; mb_y++) {
+            uint8_t *ptr     = data + (mb_y * linesize * 8 >> s->avctx->lowres);
+            int block_idx    = mb_y * s->block_stride[c];
+            int16_t (*block)[64] = &s->blocks[c][block_idx];
+            for (mb_x = 0; mb_x < mb_width; mb_x++, block++) {
+                s->idsp.idct_put(ptr, linesize, *block);
+                if (s->bits & 7)
+                    shift_output(s, ptr, linesize);
+                ptr += bytes_per_pixel*8 >> s->avctx->lowres;
+            }
+        }
+    }
+}
+
 int ff_mjpeg_decode_sos(MJpegDecodeContext *s, const uint8_t *mb_bitmask,
                         int mb_bitmask_size, const AVFrame *reference)
 {
@@ -2174,6 +2194,8 @@ int ff_mjpeg_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
             break;
         case EOI:
 eoi_parser:
+            if (avctx->skip_frame != AVDISCARD_ALL && s->progressive && s->cur_scan && s->got_picture)
+                mjpeg_idct_scan_progressive_ac(s);
             s->cur_scan = 0;
             if (!s->got_picture) {
                 av_log(avctx, AV_LOG_WARNING,