[FFmpeg-devel,03/11] mpeg2_metadata, cbs_mpeg2: Fix handling of colour_description

Submitted by Andreas Rheinhardt on May 22, 2019, 1:04 a.m.

Details

Message ID 20190522010441.44257-4-andreas.rheinhardt@gmail.com
State New
Headers show

Commit Message

Andreas Rheinhardt May 22, 2019, 1:04 a.m.
If a sequence display extension is read with colour_description equal to
zero, but a user wants to add one or more of the colour_description
elements, then the colour_description elements the user did not explicitly
request to be set are set to zero and not to the value equal to
unknown/unspecified (namely 2). A value of zero is not only inappropriate,
but explicitly forbidden. This is fixed by inferring the right default
values during the reading process if the elements are absent; moreover,
changing any of the colour_description elements to zero is now no longer
permitted.

Furthermore, if a sequence display extension has to be added, the
earlier code set some fields to their default value twice. This has been
changed, too.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
---
 libavcodec/cbs_mpeg2.c                 | 15 +++++++++++++++
 libavcodec/cbs_mpeg2_syntax_template.c |  4 ++++
 libavcodec/mpeg2_metadata_bsf.c        | 18 ++++++++++++------
 3 files changed, 31 insertions(+), 6 deletions(-)

Comments

Mark Thompson May 28, 2019, 11:05 p.m.
On 22/05/2019 02:04, Andreas Rheinhardt wrote:
> If a sequence display extension is read with colour_description equal to
> zero, but a user wants to add one or more of the colour_description
> elements, then the colour_description elements the user did not explicitly
> request to be set are set to zero and not to the value equal to
> unknown/unspecified (namely 2). A value of zero is not only inappropriate,
> but explicitly forbidden. This is fixed by inferring the right default
> values during the reading process if the elements are absent; moreover,
> changing any of the colour_description elements to zero is now no longer
> permitted.
> 
> Furthermore, if a sequence display extension has to be added, the
> earlier code set some fields to their default value twice. This has been
> changed, too.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
> ---
>  libavcodec/cbs_mpeg2.c                 | 15 +++++++++++++++
>  libavcodec/cbs_mpeg2_syntax_template.c |  4 ++++
>  libavcodec/mpeg2_metadata_bsf.c        | 18 ++++++++++++------
>  3 files changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
> index 1d319e0947..437eac88a3 100644
> --- a/libavcodec/cbs_mpeg2.c
> +++ b/libavcodec/cbs_mpeg2.c
> @@ -71,6 +71,10 @@
>      (get_bits_left(rw) >= width && \
>       (var = show_bits(rw, width)) == (compare))
>  
> +#define infer(name, value) do { \
> +        current->name = value; \
> +    } while (0)
> +
>  #include "cbs_mpeg2_syntax_template.c"
>  
>  #undef READ
> @@ -79,6 +83,7 @@
>  #undef xui
>  #undef marker_bit
>  #undef nextbits
> +#undef infer
>  
>  
>  #define WRITE
> @@ -97,6 +102,15 @@
>  
>  #define nextbits(width, compare, var) (var)
>  
> +#define infer(name, value) do { \
> +        if (current->name != (value)) { \
> +            av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
> +                   "%s does not match inferred value: " \
> +                   "%"PRId64", but should be %"PRId64".\n", \
> +                   #name, (int64_t)current->name, (int64_t)(value)); \
> +        } \
> +    } while (0)
> +
>  #include "cbs_mpeg2_syntax_template.c"
>  
>  #undef READ
> @@ -105,6 +119,7 @@
>  #undef xui
>  #undef marker_bit
>  #undef nextbits
> +#undef infer
>  
>  
>  static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
> diff --git a/libavcodec/cbs_mpeg2_syntax_template.c b/libavcodec/cbs_mpeg2_syntax_template.c
> index b9d53682fe..87db0ad039 100644
> --- a/libavcodec/cbs_mpeg2_syntax_template.c
> +++ b/libavcodec/cbs_mpeg2_syntax_template.c
> @@ -144,6 +144,10 @@ static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContex
>          uir(8, transfer_characteristics);
>          uir(8, matrix_coefficients);
>  #endif
> +    } else {
> +        infer(colour_primaries,         2);
> +        infer(transfer_characteristics, 2);
> +        infer(matrix_coefficients,      2);
>      }
>  
>      ui(14, display_horizontal_size);
> diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
> index ba3a74afda..5aed41a008 100644
> --- a/libavcodec/mpeg2_metadata_bsf.c
> +++ b/libavcodec/mpeg2_metadata_bsf.c
> @@ -147,18 +147,12 @@ static int mpeg2_metadata_update_fragment(AVBSFContext *bsf,
>  
>              if (ctx->colour_primaries >= 0)
>                  sde->colour_primaries = ctx->colour_primaries;
> -            else if (add_sde)
> -                sde->colour_primaries = 2;
>  
>              if (ctx->transfer_characteristics >= 0)
>                  sde->transfer_characteristics = ctx->transfer_characteristics;
> -            else if (add_sde)
> -                sde->transfer_characteristics = 2;
>  
>              if (ctx->matrix_coefficients >= 0)
>                  sde->matrix_coefficients = ctx->matrix_coefficients;
> -            else if (add_sde)
> -                sde->matrix_coefficients = 2;
>          }
>      }
>  
> @@ -229,6 +223,18 @@ static int mpeg2_metadata_init(AVBSFContext *bsf)
>      CodedBitstreamFragment *frag = &ctx->fragment;
>      int err;
>  
> +#define VALIDITY_CHECK(name) do { \
> +        if (!ctx->name) { \
> +            av_log(bsf, AV_LOG_ERROR, "The value 0 for %s is " \
> +                                      "forbidden.\n", #name); \
> +            return AVERROR(EINVAL); \
> +        } \
> +    } while (0)
> +    VALIDITY_CHECK(colour_primaries);
> +    VALIDITY_CHECK(transfer_characteristics);
> +    VALIDITY_CHECK(matrix_coefficients);
> +#undef VALIDITY_CHECK

Perhaps we could use the normal option checking to enforce this?  Suppose we change the range from [-1, 255] to [0, 255] and make the do-nothing default value 0.  Then the checks above become ctx->colour_primaries > 0 and this separate test is not needed.

> +
>      err = ff_cbs_init(&ctx->cbc, AV_CODEC_ID_MPEG2VIDEO, bsf);
>      if (err < 0)
>          return err;
> 

- Mark
Andreas Rheinhardt May 29, 2019, 4:12 a.m.
Mark Thompson:
> On 22/05/2019 02:04, Andreas Rheinhardt wrote:
>> If a sequence display extension is read with colour_description equal to
>> zero, but a user wants to add one or more of the colour_description
>> elements, then the colour_description elements the user did not explicitly
>> request to be set are set to zero and not to the value equal to
>> unknown/unspecified (namely 2). A value of zero is not only inappropriate,
>> but explicitly forbidden. This is fixed by inferring the right default
>> values during the reading process if the elements are absent; moreover,
>> changing any of the colour_description elements to zero is now no longer
>> permitted.
>>
>> Furthermore, if a sequence display extension has to be added, the
>> earlier code set some fields to their default value twice. This has been
>> changed, too.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
>> ---
>>  libavcodec/cbs_mpeg2.c                 | 15 +++++++++++++++
>>  libavcodec/cbs_mpeg2_syntax_template.c |  4 ++++
>>  libavcodec/mpeg2_metadata_bsf.c        | 18 ++++++++++++------
>>  3 files changed, 31 insertions(+), 6 deletions(-)
>>
>> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
>> index 1d319e0947..437eac88a3 100644
>> --- a/libavcodec/cbs_mpeg2.c
>> +++ b/libavcodec/cbs_mpeg2.c
>> @@ -71,6 +71,10 @@
>>      (get_bits_left(rw) >= width && \
>>       (var = show_bits(rw, width)) == (compare))
>>  
>> +#define infer(name, value) do { \
>> +        current->name = value; \
>> +    } while (0)
>> +
>>  #include "cbs_mpeg2_syntax_template.c"
>>  
>>  #undef READ
>> @@ -79,6 +83,7 @@
>>  #undef xui
>>  #undef marker_bit
>>  #undef nextbits
>> +#undef infer
>>  
>>  
>>  #define WRITE
>> @@ -97,6 +102,15 @@
>>  
>>  #define nextbits(width, compare, var) (var)
>>  
>> +#define infer(name, value) do { \
>> +        if (current->name != (value)) { \
>> +            av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
>> +                   "%s does not match inferred value: " \
>> +                   "%"PRId64", but should be %"PRId64".\n", \
>> +                   #name, (int64_t)current->name, (int64_t)(value)); \
>> +        } \
>> +    } while (0)
>> +
>>  #include "cbs_mpeg2_syntax_template.c"
>>  
>>  #undef READ
>> @@ -105,6 +119,7 @@
>>  #undef xui
>>  #undef marker_bit
>>  #undef nextbits
>> +#undef infer
>>  
>>  
>>  static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
>> diff --git a/libavcodec/cbs_mpeg2_syntax_template.c b/libavcodec/cbs_mpeg2_syntax_template.c
>> index b9d53682fe..87db0ad039 100644
>> --- a/libavcodec/cbs_mpeg2_syntax_template.c
>> +++ b/libavcodec/cbs_mpeg2_syntax_template.c
>> @@ -144,6 +144,10 @@ static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContex
>>          uir(8, transfer_characteristics);
>>          uir(8, matrix_coefficients);
>>  #endif
>> +    } else {
>> +        infer(colour_primaries,         2);
>> +        infer(transfer_characteristics, 2);
>> +        infer(matrix_coefficients,      2);
>>      }
>>  
>>      ui(14, display_horizontal_size);
>> diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
>> index ba3a74afda..5aed41a008 100644
>> --- a/libavcodec/mpeg2_metadata_bsf.c
>> +++ b/libavcodec/mpeg2_metadata_bsf.c
>> @@ -147,18 +147,12 @@ static int mpeg2_metadata_update_fragment(AVBSFContext *bsf,
>>  
>>              if (ctx->colour_primaries >= 0)
>>                  sde->colour_primaries = ctx->colour_primaries;
>> -            else if (add_sde)
>> -                sde->colour_primaries = 2;
>>  
>>              if (ctx->transfer_characteristics >= 0)
>>                  sde->transfer_characteristics = ctx->transfer_characteristics;
>> -            else if (add_sde)
>> -                sde->transfer_characteristics = 2;
>>  
>>              if (ctx->matrix_coefficients >= 0)
>>                  sde->matrix_coefficients = ctx->matrix_coefficients;
>> -            else if (add_sde)
>> -                sde->matrix_coefficients = 2;
>>          }
>>      }
>>  
>> @@ -229,6 +223,18 @@ static int mpeg2_metadata_init(AVBSFContext *bsf)
>>      CodedBitstreamFragment *frag = &ctx->fragment;
>>      int err;
>>  
>> +#define VALIDITY_CHECK(name) do { \
>> +        if (!ctx->name) { \
>> +            av_log(bsf, AV_LOG_ERROR, "The value 0 for %s is " \
>> +                                      "forbidden.\n", #name); \
>> +            return AVERROR(EINVAL); \
>> +        } \
>> +    } while (0)
>> +    VALIDITY_CHECK(colour_primaries);
>> +    VALIDITY_CHECK(transfer_characteristics);
>> +    VALIDITY_CHECK(matrix_coefficients);
>> +#undef VALIDITY_CHECK
> 
> Perhaps we could use the normal option checking to enforce this?  Suppose we change the range from [-1, 255] to [0, 255] and make the do-nothing default value 0.  Then the checks above become ctx->colour_primaries > 0 and this separate test is not needed.
> 
There are two reasons why I didn't do this:
1. A user with only a background in (say) H.264 or H.265 might want to
put a value of 0 in there, thinking it is a legel value. Said user is
going to be surprised.
2. I have not given up hope on updating the AVCodecParameters (do you
remember
https://ffmpeg.org/pipermail/ffmpeg-devel/2018-December/236990.html ?)
and if 0 means do nothing, then it is not in line with the rest of cbs
and needs special handling there.
But both reasons are very weak and so I will consider your suggestion.
>> +
>>      err = ff_cbs_init(&ctx->cbc, AV_CODEC_ID_MPEG2VIDEO, bsf);
>>      if (err < 0)
>>          return err;
>>
> 
> - Mark
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
Mark Thompson June 2, 2019, 4:52 p.m.
On 29/05/2019 05:12, Andreas Rheinhardt wrote:
> Mark Thompson:
>> On 22/05/2019 02:04, Andreas Rheinhardt wrote:
>>> If a sequence display extension is read with colour_description equal to
>>> zero, but a user wants to add one or more of the colour_description
>>> elements, then the colour_description elements the user did not explicitly
>>> request to be set are set to zero and not to the value equal to
>>> unknown/unspecified (namely 2). A value of zero is not only inappropriate,
>>> but explicitly forbidden. This is fixed by inferring the right default
>>> values during the reading process if the elements are absent; moreover,
>>> changing any of the colour_description elements to zero is now no longer
>>> permitted.
>>>
>>> Furthermore, if a sequence display extension has to be added, the
>>> earlier code set some fields to their default value twice. This has been
>>> changed, too.
>>>
>>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
>>> ---
>>>  libavcodec/cbs_mpeg2.c                 | 15 +++++++++++++++
>>>  libavcodec/cbs_mpeg2_syntax_template.c |  4 ++++
>>>  libavcodec/mpeg2_metadata_bsf.c        | 18 ++++++++++++------
>>>  3 files changed, 31 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
>>> index 1d319e0947..437eac88a3 100644
>>> --- a/libavcodec/cbs_mpeg2.c
>>> +++ b/libavcodec/cbs_mpeg2.c
>>> @@ -71,6 +71,10 @@
>>>      (get_bits_left(rw) >= width && \
>>>       (var = show_bits(rw, width)) == (compare))
>>>  
>>> +#define infer(name, value) do { \
>>> +        current->name = value; \
>>> +    } while (0)
>>> +
>>>  #include "cbs_mpeg2_syntax_template.c"
>>>  
>>>  #undef READ
>>> @@ -79,6 +83,7 @@
>>>  #undef xui
>>>  #undef marker_bit
>>>  #undef nextbits
>>> +#undef infer
>>>  
>>>  
>>>  #define WRITE
>>> @@ -97,6 +102,15 @@
>>>  
>>>  #define nextbits(width, compare, var) (var)
>>>  
>>> +#define infer(name, value) do { \
>>> +        if (current->name != (value)) { \
>>> +            av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
>>> +                   "%s does not match inferred value: " \
>>> +                   "%"PRId64", but should be %"PRId64".\n", \
>>> +                   #name, (int64_t)current->name, (int64_t)(value)); \
>>> +        } \
>>> +    } while (0)
>>> +
>>>  #include "cbs_mpeg2_syntax_template.c"
>>>  
>>>  #undef READ
>>> @@ -105,6 +119,7 @@
>>>  #undef xui
>>>  #undef marker_bit
>>>  #undef nextbits
>>> +#undef infer
>>>  
>>>  
>>>  static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
>>> diff --git a/libavcodec/cbs_mpeg2_syntax_template.c b/libavcodec/cbs_mpeg2_syntax_template.c
>>> index b9d53682fe..87db0ad039 100644
>>> --- a/libavcodec/cbs_mpeg2_syntax_template.c
>>> +++ b/libavcodec/cbs_mpeg2_syntax_template.c
>>> @@ -144,6 +144,10 @@ static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContex
>>>          uir(8, transfer_characteristics);
>>>          uir(8, matrix_coefficients);
>>>  #endif
>>> +    } else {
>>> +        infer(colour_primaries,         2);
>>> +        infer(transfer_characteristics, 2);
>>> +        infer(matrix_coefficients,      2);
>>>      }
>>>  
>>>      ui(14, display_horizontal_size);
>>> diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
>>> index ba3a74afda..5aed41a008 100644
>>> --- a/libavcodec/mpeg2_metadata_bsf.c
>>> +++ b/libavcodec/mpeg2_metadata_bsf.c
>>> @@ -147,18 +147,12 @@ static int mpeg2_metadata_update_fragment(AVBSFContext *bsf,
>>>  
>>>              if (ctx->colour_primaries >= 0)
>>>                  sde->colour_primaries = ctx->colour_primaries;
>>> -            else if (add_sde)
>>> -                sde->colour_primaries = 2;
>>>  
>>>              if (ctx->transfer_characteristics >= 0)
>>>                  sde->transfer_characteristics = ctx->transfer_characteristics;
>>> -            else if (add_sde)
>>> -                sde->transfer_characteristics = 2;
>>>  
>>>              if (ctx->matrix_coefficients >= 0)
>>>                  sde->matrix_coefficients = ctx->matrix_coefficients;
>>> -            else if (add_sde)
>>> -                sde->matrix_coefficients = 2;
>>>          }
>>>      }
>>>  
>>> @@ -229,6 +223,18 @@ static int mpeg2_metadata_init(AVBSFContext *bsf)
>>>      CodedBitstreamFragment *frag = &ctx->fragment;
>>>      int err;
>>>  
>>> +#define VALIDITY_CHECK(name) do { \
>>> +        if (!ctx->name) { \
>>> +            av_log(bsf, AV_LOG_ERROR, "The value 0 for %s is " \
>>> +                                      "forbidden.\n", #name); \
>>> +            return AVERROR(EINVAL); \
>>> +        } \
>>> +    } while (0)
>>> +    VALIDITY_CHECK(colour_primaries);
>>> +    VALIDITY_CHECK(transfer_characteristics);
>>> +    VALIDITY_CHECK(matrix_coefficients);
>>> +#undef VALIDITY_CHECK
>>
>> Perhaps we could use the normal option checking to enforce this?  Suppose we change the range from [-1, 255] to [0, 255] and make the do-nothing default value 0.  Then the checks above become ctx->colour_primaries > 0 and this separate test is not needed.
>>
> There are two reasons why I didn't do this:
> 1. A user with only a background in (say) H.264 or H.265 might want to
> put a value of 0 in there, thinking it is a legel value. Said user is
> going to be surprised.
> 2. I have not given up hope on updating the AVCodecParameters (do you
> remember
> https://ffmpeg.org/pipermail/ffmpeg-devel/2018-December/236990.html ?)
> and if 0 means do nothing, then it is not in line with the rest of cbs
> and needs special handling there.
> But both reasons are very weak and so I will consider your suggestion.

Fair enough.  I have no actual objection to your approach; it was mostly a thought that the code could be slightly simpler.

Thanks,

- Mark

Patch hide | download patch | download mbox

diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index 1d319e0947..437eac88a3 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -71,6 +71,10 @@ 
     (get_bits_left(rw) >= width && \
      (var = show_bits(rw, width)) == (compare))
 
+#define infer(name, value) do { \
+        current->name = value; \
+    } while (0)
+
 #include "cbs_mpeg2_syntax_template.c"
 
 #undef READ
@@ -79,6 +83,7 @@ 
 #undef xui
 #undef marker_bit
 #undef nextbits
+#undef infer
 
 
 #define WRITE
@@ -97,6 +102,15 @@ 
 
 #define nextbits(width, compare, var) (var)
 
+#define infer(name, value) do { \
+        if (current->name != (value)) { \
+            av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
+                   "%s does not match inferred value: " \
+                   "%"PRId64", but should be %"PRId64".\n", \
+                   #name, (int64_t)current->name, (int64_t)(value)); \
+        } \
+    } while (0)
+
 #include "cbs_mpeg2_syntax_template.c"
 
 #undef READ
@@ -105,6 +119,7 @@ 
 #undef xui
 #undef marker_bit
 #undef nextbits
+#undef infer
 
 
 static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
diff --git a/libavcodec/cbs_mpeg2_syntax_template.c b/libavcodec/cbs_mpeg2_syntax_template.c
index b9d53682fe..87db0ad039 100644
--- a/libavcodec/cbs_mpeg2_syntax_template.c
+++ b/libavcodec/cbs_mpeg2_syntax_template.c
@@ -144,6 +144,10 @@  static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContex
         uir(8, transfer_characteristics);
         uir(8, matrix_coefficients);
 #endif
+    } else {
+        infer(colour_primaries,         2);
+        infer(transfer_characteristics, 2);
+        infer(matrix_coefficients,      2);
     }
 
     ui(14, display_horizontal_size);
diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
index ba3a74afda..5aed41a008 100644
--- a/libavcodec/mpeg2_metadata_bsf.c
+++ b/libavcodec/mpeg2_metadata_bsf.c
@@ -147,18 +147,12 @@  static int mpeg2_metadata_update_fragment(AVBSFContext *bsf,
 
             if (ctx->colour_primaries >= 0)
                 sde->colour_primaries = ctx->colour_primaries;
-            else if (add_sde)
-                sde->colour_primaries = 2;
 
             if (ctx->transfer_characteristics >= 0)
                 sde->transfer_characteristics = ctx->transfer_characteristics;
-            else if (add_sde)
-                sde->transfer_characteristics = 2;
 
             if (ctx->matrix_coefficients >= 0)
                 sde->matrix_coefficients = ctx->matrix_coefficients;
-            else if (add_sde)
-                sde->matrix_coefficients = 2;
         }
     }
 
@@ -229,6 +223,18 @@  static int mpeg2_metadata_init(AVBSFContext *bsf)
     CodedBitstreamFragment *frag = &ctx->fragment;
     int err;
 
+#define VALIDITY_CHECK(name) do { \
+        if (!ctx->name) { \
+            av_log(bsf, AV_LOG_ERROR, "The value 0 for %s is " \
+                                      "forbidden.\n", #name); \
+            return AVERROR(EINVAL); \
+        } \
+    } while (0)
+    VALIDITY_CHECK(colour_primaries);
+    VALIDITY_CHECK(transfer_characteristics);
+    VALIDITY_CHECK(matrix_coefficients);
+#undef VALIDITY_CHECK
+
     err = ff_cbs_init(&ctx->cbc, AV_CODEC_ID_MPEG2VIDEO, bsf);
     if (err < 0)
         return err;