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

[walter harms]

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, ...).

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");