cbs_mpeg2: Improve checks for invalid values

MPEG-2 contains several elements that mustn't be zero according to the
specifications: horizontal/vertical_size_value, aspect_ratio_information,
frame_rate_code, the quantiser matrices, the colour_description
elements, picture_coding_type, the f_code[r][s] values and
quantiser_scale_code. It is now checked that the invalid values don't
occur.

The colour_description elements are treated specially in this regard:
Given that there are files in the wild which use illegal values for the
colour_description elements (some of them created by mpeg2_metadata),
they will be corrected to the value meaning "unknown" (namely 2) during
reading. This has been done in such a way that trace_headers will
nevertheless report the original value, together with a message about
the fixup.

Furthermore, the trace_headers output of user_data has been beautified.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

2 files changed, 50 insertions, 30 deletions

diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index f9f1d86b49..4605b2056e 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -41,20 +41,24 @@
 #define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
 
 #define ui(width, name) \
-        xui(width, name, current->name, 0)
+        xui(width, name, current->name, 0, MAX_UINT_BITS(width), 0)
+#define uir(width, name) \
+        xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0)
 #define uis(width, name, subs, ...) \
-        xui(width, name, current->name, subs, __VA_ARGS__)
+        xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
+#define uirs(width, name, subs, ...) \
+        xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
 
 
 #define READ
 #define READWRITE read
 #define RWContext GetBitContext
 
-#define xui(width, name, var, subs, ...) do { \
+#define xui(width, name, var, range_min, range_max, subs, ...) do { \
         uint32_t value = 0; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
-                                   &value, 0, (1 << width) - 1)); \
+                                   &value, range_min, range_max)); \
         var = value; \
     } while (0)
 
@@ -81,10 +85,10 @@
 #define READWRITE write
 #define RWContext PutBitContext
 
-#define xui(width, name, var, subs, ...) do { \
+#define xui(width, name, var, range_min, range_max, subs, ...) do { \
         CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
                                     SUBSCRIPTS(subs, __VA_ARGS__), \
-                                    var, 0, (1 << width) - 1)); \
+                                    var, range_min, range_max)); \
     } while (0)
 
 #define marker_bit() do { \
diff --git a/libavcodec/cbs_mpeg2_syntax_template.c b/libavcodec/cbs_mpeg2_syntax_template.c
index 10aaea7734..b9d53682fe 100644
--- a/libavcodec/cbs_mpeg2_syntax_template.c
+++ b/libavcodec/cbs_mpeg2_syntax_template.c
@@ -26,14 +26,14 @@ static int FUNC(sequence_header)(CodedBitstreamContext *ctx, RWContext *rw,
 
     ui(8,  sequence_header_code);
 
-    ui(12, horizontal_size_value);
-    ui(12, vertical_size_value);
+    uir(12, horizontal_size_value);
+    uir(12, vertical_size_value);
 
     mpeg2->horizontal_size = current->horizontal_size_value;
     mpeg2->vertical_size   = current->vertical_size_value;
 
-    ui(4,  aspect_ratio_information);
-    ui(4,  frame_rate_code);
+    uir(4, aspect_ratio_information);
+    uir(4, frame_rate_code);
     ui(18, bit_rate_value);
 
     marker_bit();
@@ -44,13 +44,13 @@ static int FUNC(sequence_header)(CodedBitstreamContext *ctx, RWContext *rw,
     ui(1, load_intra_quantiser_matrix);
     if (current->load_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, intra_quantiser_matrix[i], 1, i);
+            uirs(8, intra_quantiser_matrix[i], 1, i);
     }
 
     ui(1, load_non_intra_quantiser_matrix);
     if (current->load_non_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, non_intra_quantiser_matrix[i], 1, i);
+            uirs(8, non_intra_quantiser_matrix[i], 1, i);
     }
 
     return 0;
@@ -79,7 +79,7 @@ static int FUNC(user_data)(CodedBitstreamContext *ctx, RWContext *rw,
 #endif
 
     for (k = 0; k < current->user_data_length; k++)
-        xui(8, user_data, current->user_data[k], 0);
+        uis(8, user_data[k], 1, k);
 
     return 0;
 }
@@ -125,9 +125,25 @@ static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContex
 
     ui(1, colour_description);
     if (current->colour_description) {
-        ui(8, colour_primaries);
-        ui(8, transfer_characteristics);
-        ui(8, matrix_coefficients);
+#ifdef READ
+#define READ_AND_PATCH(name) do { \
+        ui(8, name); \
+        if (current->name == 0) { \
+            current->name = 2; \
+            av_log(ctx->log_ctx, AV_LOG_WARNING, "%s in a sequence display " \
+                   "extension had the invalid value 0. Setting it to 2 " \
+                   "(meaning unknown) instead.\n", #name); \
+        } \
+    } while (0)
+        READ_AND_PATCH(colour_primaries);
+        READ_AND_PATCH(transfer_characteristics);
+        READ_AND_PATCH(matrix_coefficients);
+#undef READ_AND_PATCH
+#else
+        uir(8, colour_primaries);
+        uir(8, transfer_characteristics);
+        uir(8, matrix_coefficients);
+#endif
     }
 
     ui(14, display_horizontal_size);
@@ -163,7 +179,7 @@ static int FUNC(picture_header)(CodedBitstreamContext *ctx, RWContext *rw,
     ui(8,  picture_start_code);
 
     ui(10, temporal_reference);
-    ui(3,  picture_coding_type);
+    uir(3, picture_coding_type);
     ui(16, vbv_delay);
 
     if (current->picture_coding_type == 2 ||
@@ -190,10 +206,10 @@ static int FUNC(picture_coding_extension)(CodedBitstreamContext *ctx, RWContext
 
     HEADER("Picture Coding Extension");
 
-    ui(4, f_code[0][0]);
-    ui(4, f_code[0][1]);
-    ui(4, f_code[1][0]);
-    ui(4, f_code[1][1]);
+    uir(4, f_code[0][0]);
+    uir(4, f_code[0][1]);
+    uir(4, f_code[1][0]);
+    uir(4, f_code[1][1]);
 
     ui(2, intra_dc_precision);
     ui(2, picture_structure);
@@ -250,25 +266,25 @@ static int FUNC(quant_matrix_extension)(CodedBitstreamContext *ctx, RWContext *r
     ui(1, load_intra_quantiser_matrix);
     if (current->load_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, intra_quantiser_matrix[i], 1, i);
+            uirs(8, intra_quantiser_matrix[i], 1, i);
     }
 
     ui(1, load_non_intra_quantiser_matrix);
     if (current->load_non_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, non_intra_quantiser_matrix[i], 1, i);
+            uirs(8, non_intra_quantiser_matrix[i], 1, i);
     }
 
     ui(1, load_chroma_intra_quantiser_matrix);
     if (current->load_chroma_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, intra_quantiser_matrix[i], 1, i);
+            uirs(8, intra_quantiser_matrix[i], 1, i);
     }
 
     ui(1, load_chroma_non_intra_quantiser_matrix);
     if (current->load_chroma_non_intra_quantiser_matrix) {
         for (i = 0; i < 64; i++)
-            uis(8, chroma_non_intra_quantiser_matrix[i], 1, i);
+            uirs(8, chroma_non_intra_quantiser_matrix[i], 1, i);
     }
 
     return 0;
@@ -342,7 +358,7 @@ static int FUNC(slice_header)(CodedBitstreamContext *ctx, RWContext *rw,
             ui(7, priority_breakpoint);
     }
 
-    ui(5, quantiser_scale_code);
+    uir(5, quantiser_scale_code);
 
     if (nextbits(1, 1, current->slice_extension_flag)) {
         ui(1, slice_extension_flag);
@@ -366,16 +382,16 @@ static int FUNC(slice_header)(CodedBitstreamContext *ctx, RWContext *rw,
                 if (!current->extra_information)
                     return AVERROR(ENOMEM);
                 for (k = 0; k < current->extra_information_length; k++) {
-                    xui(1, extra_bit_slice, bit, 0);
+                    xui(1, extra_bit_slice, bit, 1, 1, 0);
                     xui(8, extra_information_slice[k],
-                        current->extra_information[k], 1, k);
+                        current->extra_information[k], 0, 255, 1, k);
                 }
             }
 #else
             for (k = 0; k < current->extra_information_length; k++) {
-                xui(1, extra_bit_slice, 1, 0);
+                xui(1, extra_bit_slice, 1, 1, 1, 0);
                 xui(8, extra_information_slice[k],
-                    current->extra_information[k], 1, k);
+                    current->extra_information[k], 0, 255, 1, k);
             }
 #endif
         }