[FFmpeg-devel] [PATCH] avcodec/tiff: Add support for recognizing DNG files

[velocityra at gmail.com]

From: Nick Renieris <velocityra at gmail.com>

Prints "DNG images are not supported" if it finds a TIFF image with
the 'DNGVersion' tag.  In DNG images with the .tiff extension, it
solves the issue where the TIFF thumbnail in IFD 0 was incorrectly
parsed (related confusion: [1]).  The user can still decode those
with the -subimage option.  Also prints the DNG version of the file
on the debug channel.

Additionally:
 - Renamed TIFF_WHITE_LEVEL to DNG_WHITE_LEVEL since it is specified
   in the DNG spec.
 - Added/changed some comments to be more precise in differentiating
   between TIFF, TIFF/EP and DNG values.

Related to ticket: https://trac.ffmpeg.org/ticket/4364

---

[1]: https://superuser.com/questions/546879/creating-video-from-dng-images-with-ffmpeg

Signed-off-by: Nick Renieris <velocityra at gmail.com>
---
 libavcodec/tiff.c  | 29 ++++++++++++++++++++++++++++-
 libavcodec/tiff.h  | 18 +++++++++++++-----
 libavformat/img2.c |  1 +
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/libavcodec/tiff.c b/libavcodec/tiff.c
index 112f5b52f4..41c63900fd 100644
--- a/libavcodec/tiff.c
+++ b/libavcodec/tiff.c
@@ -70,6 +70,7 @@ typedef struct TiffContext {
     int fill_order;
     uint32_t res[4];
 
+    int dng_mode; /** denotes that this is a DNG image */
     int is_bayer;
     uint8_t pattern[4];
     unsigned white_level;
@@ -1077,7 +1078,7 @@ static int tiff_decode_tag(TiffContext *s, AVFrame *frame)
     case TIFF_SUB_IFDS:
         s->sub_ifd = value;
         break;
-    case TIFF_WHITE_LEVEL:
+    case DNG_WHITE_LEVEL:
         s->white_level = value;
         break;
     case TIFF_CFA_PATTERN_DIM:
@@ -1322,6 +1323,20 @@ static int tiff_decode_tag(TiffContext *s, AVFrame *frame)
     case TIFF_SOFTWARE_NAME:
         ADD_METADATA(count, "software", NULL);
         break;
+    case DNG_VERSION:
+        if (count == 4) {
+            unsigned int ver[4];
+            ver[0] = ff_tget(&s->gb, type, s->le);
+            ver[1] = ff_tget(&s->gb, type, s->le);
+            ver[2] = ff_tget(&s->gb, type, s->le);
+            ver[3] = ff_tget(&s->gb, type, s->le);
+
+            av_log(s->avctx, AV_LOG_DEBUG, "DNG file, version %u.%u.%u.%u\n",
+                ver[0], ver[1], ver[2], ver[3]);
+
+            s->dng_mode = 1;
+        }
+        break;
     default:
         if (s->avctx->err_recognition & AV_EF_EXPLODE) {
             av_log(s->avctx, AV_LOG_ERROR,
@@ -1375,6 +1390,7 @@ again:
     s->fill_order  = 0;
     s->white_level = 0;
     s->is_bayer    = 0;
+    s->dng_mode    = 0;
     free_geotags(s);
 
     // Reset these offsets so we can tell if they were set this frame
@@ -1389,6 +1405,17 @@ again:
             return ret;
     }
 
+    if (s->dng_mode) {
+        av_log(avctx, AV_LOG_ERROR, "DNG images are not supported\n");
+
+        if (s->get_subimage) {
+            av_log(avctx, AV_LOG_INFO, "Decoding embedded TIFF thumbnail in DNG image\n");
+        } else {
+            av_log(avctx, AV_LOG_INFO, "Consider using -subimage for decoding the embedded thumbail instead\n");
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
     if (s->sub_ifd && s->get_subimage) {
         off = s->sub_ifd;
         if (off >= UINT_MAX - 14 || avpkt->size < off + 14) {
diff --git a/libavcodec/tiff.h b/libavcodec/tiff.h
index 4b08650108..3cede299f6 100644
--- a/libavcodec/tiff.h
+++ b/libavcodec/tiff.h
@@ -20,7 +20,7 @@
 
 /**
  * @file
- * TIFF tables
+ * TIFF constants & data structures
  *
  * For more information about the TIFF format, check the official docs at:
  * http://partners.adobe.com/public/developer/tiff/index.html
@@ -33,7 +33,7 @@
 #include <stdint.h>
 #include "tiff_common.h"
 
-/** abridged list of TIFF tags */
+/** abridged list of TIFF and TIFF/EP tags */
 enum TiffTags {
     TIFF_SUBFILE            = 0xfe,
     TIFF_WIDTH              = 0x100,
@@ -85,10 +85,17 @@ enum TiffTags {
     TIFF_GEO_KEY_DIRECTORY  = 0x87AF,
     TIFF_GEO_DOUBLE_PARAMS  = 0x87B0,
     TIFF_GEO_ASCII_PARAMS   = 0x87B1,
-    TIFF_WHITE_LEVEL        = 0xC61D,
 };
 
-/** list of TIFF compression types */
+/** abridged list of DNG tags */
+enum DngTags
+{
+    DNG_VERSION             = 0xC612,
+    DNG_BACKWARD_VERSION    = 0xC613,
+    DNG_WHITE_LEVEL         = 0xC61D,
+};
+
+/** list of TIFF, TIFF/EP and DNG compression types */
 enum TiffCompr {
     TIFF_RAW = 1,
     TIFF_CCITT_RLE,
@@ -151,6 +158,7 @@ enum TiffGeoTagKey {
     TIFF_VERTICAL_UNITS_GEOKEY               = 4099
 };
 
+/** list of TIFF, TIFF/AP and DNG PhotometricInterpretation (TIFF_PHOTOMETRIC) values */
 enum TiffPhotometric {
     TIFF_PHOTOMETRIC_NONE       = -1,
     TIFF_PHOTOMETRIC_WHITE_IS_ZERO,      /* mono or grayscale, 0 is white */
@@ -163,7 +171,7 @@ enum TiffPhotometric {
     TIFF_PHOTOMETRIC_CIE_LAB    = 8,     /* 1976 CIE L*a*b* */
     TIFF_PHOTOMETRIC_ICC_LAB,            /* ICC L*a*b* */
     TIFF_PHOTOMETRIC_ITU_LAB,            /* ITU L*a*b* */
-    TIFF_PHOTOMETRIC_CFA        = 32803, /* Color Filter Array (DNG) */
+    TIFF_PHOTOMETRIC_CFA        = 32803, /* Color Filter Array (TIFF/AP and DNG) */
     TIFF_PHOTOMETRIC_LOG_L      = 32844, /* CIE Log2(L) */
     TIFF_PHOTOMETRIC_LOG_LUV,            /* CIE Log L*u*v* */
     TIFF_PHOTOMETRIC_LINEAR_RAW = 34892, /* Linear Raw (DNG) */
diff --git a/libavformat/img2.c b/libavformat/img2.c
index 8432cc0955..16bc9d2abd 100644
--- a/libavformat/img2.c
+++ b/libavformat/img2.c
@@ -51,6 +51,7 @@ const IdStrMap ff_img_tags[] = {
     { AV_CODEC_ID_TARGA,      "tga"      },
     { AV_CODEC_ID_TIFF,       "tiff"     },
     { AV_CODEC_ID_TIFF,       "tif"      },
+    { AV_CODEC_ID_TIFF,       "dng"      },
     { AV_CODEC_ID_SGI,        "sgi"      },
     { AV_CODEC_ID_PTX,        "ptx"      },
     { AV_CODEC_ID_PCX,        "pcx"      },
-- 
2.17.1.windows.2