[PATCH 6/8] edid-decode: support HLG, decode luminance values

[Hans Verkuil]

On 09/08/17 10:28, walter harms wrote:
> 
> 
> Am 07.09.2017 20:03, schrieb Hans Verkuil:
>> From: Hans Verkuil <hans.verkuil at cisco.com>
>>
>> Add support for the new CTA-861-G Hybrid Log-Gamma transfer
>> function.
>>
>> Also decode the luminance values in the static metadata block to
>> cd/m^2 values.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
>> ---
>>  Makefile      |  2 +-
>>  edid-decode.c | 15 ++++++++++-----
>>  2 files changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 21b811ed..b698c579 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -2,7 +2,7 @@ bindir ?= /usr/bin
>>  mandir ?= /usr/share/man
>>  
>>  edid-decode: edid-decode.c
>> -	$(CC) $(CFLAGS) -g -Wall -o $@ $<
>> +	$(CC) $(CFLAGS) -g -Wall -lm -o $@ $<
>>  
>>  clean:
>>  	rm -f edid-decode
>> diff --git a/edid-decode.c b/edid-decode.c
>> index d0da48e2..effcf777 100644
>> --- a/edid-decode.c
>> +++ b/edid-decode.c
>> @@ -31,6 +31,7 @@
>>  #include <stdlib.h>
>>  #include <time.h>
>>  #include <ctype.h>
>> +#include <math.h>
>>  
>>  #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
>>  #define min(a, b) ((a) < (b) ? (a) : (b))
>> @@ -1827,10 +1828,11 @@ static const char *eotf_map[] = {
>>      "Traditional gamma - SDR luminance range",
>>      "Traditional gamma - HDR luminance range",
>>      "SMPTE ST2084",
>> +    "Hybrid Log-Gamma",
>>  };
>>  
>>  static void
>> -cea_hdr_metadata_block(unsigned char *x)
>> +cea_hdr_static_metadata_block(unsigned char *x)
>>  {
>>      int length = x[0] & 0x1f;
>>      int i;
>> @@ -1851,13 +1853,16 @@ cea_hdr_metadata_block(unsigned char *x)
>>      }
>>  
>>      if (length >= 4)
>> -	printf("    Desired content max luminance: %d\n", x[4]);
>> +	printf("    Desired content max luminance: %d (%.3f cd/m^2)\n",
>> +	       x[4], 50.0 * pow(2, x[4] / 32.0));
>>  
>>      if (length >= 5)
>> -	printf("    Desired content max frame-average luminance: %d\n", x[5]);
>> +	printf("    Desired content max frame-average luminance: %d (%.3f cd/m^2)\n",
>> +	       x[5], 50.0 * pow(2, x[5] / 32.0));
>>  
>>      if (length >= 6)
>> -	printf("    Desired content min luminance: %d\n", x[6]);
>> +	printf("    Desired content min luminance: %d (%.3f cd/m^2)\n",
>> +	       x[6], (50.0 * pow(2, x[4] / 32.0)) * pow(x[6] / 255.0, 2) / 100.0);
> 
> are you sure that pow(x[6] / 255.0, 2) is correct ? other terms are pow( 2, ...).

Yes, it's correct. I double checked this.

Regards,

	Hans

> 
> re,
>  wh
> 
>>  }
>>  
>>  static void
>> @@ -1924,7 +1929,7 @@ cea_block(unsigned char *x)
>>  		    break;
>>  		case 0x06:
>>  		    printf("HDR static metadata data block\n");
>> -		    cea_hdr_metadata_block(x);
>> +		    cea_hdr_static_metadata_block(x);
>>  		    break;
>>  		case 0x0d:
>>  		    printf("Video format preference data block\n");
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