[FFmpeg-devel] [PATCH v2 3/5] avfilter/vf_showinfo: display user data unregistered message

[James Almer]

On 12/18/2019 8:06 AM, lance.lmwang at gmail.com wrote:
> From: Limin Wang <lance.lmwang at gmail.com>
> 
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  libavfilter/vf_showinfo.c | 40 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/libavfilter/vf_showinfo.c b/libavfilter/vf_showinfo.c
> index 31f6b32aa4..77ee7f312c 100644
> --- a/libavfilter/vf_showinfo.c
> +++ b/libavfilter/vf_showinfo.c
> @@ -169,6 +169,43 @@ static void dump_content_light_metadata(AVFilterContext *ctx, AVFrameSideData *s
>             metadata->MaxCLL, metadata->MaxFALL);
>  }
>  
> +static int is_ascii(uint8_t ch)
> +{
> +    if (ch >= 32 && ch <= 127)

Should be < 127, i think.

> +        return 1;
> +    else
> +        return 0;
> +}
> +
> +static void dump_user_data_unregistered_metadata(AVFilterContext *ctx, AVFrameSideData *sd)
> +{
> +    const int uuid_size = 16;
> +    uint8_t *user_data = sd->data;
> +
> +    if (sd->size < uuid_size) {
> +        av_log(ctx, AV_LOG_ERROR, "invalid data(%d < UUID(%d-bytes))", sd->size, uuid_size);
> +        return;
> +    }
> +
> +    av_log(ctx, AV_LOG_INFO, "User Data Unregistered:\n");
> +    av_log(ctx, AV_LOG_INFO, "UUID=");
> +    for (int i = 0; i < uuid_size; i++)
> +        av_log(ctx, AV_LOG_INFO, "%x", user_data[i]);
> +    av_log(ctx, AV_LOG_INFO, "\n");
> +    av_log(ctx, AV_LOG_INFO, "User Data=");
> +    for (int i = uuid_size; i < sd->size; i++) {
> +        /* printable ascii */
> +        if (is_ascii(*(user_data + i))) {

user_data[i]
> +            av_log(ctx, AV_LOG_INFO, "%c", *(user_data + i));

Ditto.

> +        } else {
> +            /* don't print the last byte `\0` character for ascii */
> +            if ((i == sd->size - 1) && *(user_data + i) == 0)

Ditto.

> +                continue;
> +            av_log(ctx, AV_LOG_INFO, "%x", *(user_data + i));

Ditto.

Also, maybe print 0x%02x instead.

> +        }
> +    }

What if it's binary data where a few of the bytes are in the printable
range? It might be worth checking if the entire buffer is printable and
then choosing between using %s or %x for the whole thing.

Or maybe just not print anything at all. We're not doing it for closed
captions frame side data after all.

> +}
> +
>  static void dump_color_property(AVFilterContext *ctx, AVFrame *frame)
>  {
>      const char *color_range_str     = av_color_range_name(frame->color_range);
> @@ -319,6 +356,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
>              av_log(ctx, AV_LOG_INFO, "GOP timecode - %s", tcbuf);
>              break;
>          }
> +        case AV_FRAME_DATA_USER_DATA_UNREGISTERED:
> +            dump_user_data_unregistered_metadata(ctx, sd);
> +            break;
>          default:
>              av_log(ctx, AV_LOG_WARNING, "unknown side data type %d (%d bytes)",
>                     sd->type, sd->size);
>