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

[Limin Wang]

On Wed, Dec 18, 2019 at 12:47:49PM -0300, James Almer wrote:
> 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.
> 

yes, 127 is DEL control character

> > +        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]

yes, it's more simple

> > +            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.

sure.

> 
> > +        }
> > +    }
> 
> 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.

I prefer to print the data, for most of user data is string, so it'll
helpful for user to dump the info. I'll add a function a check the entire buffer
first like below function:

 static int string_is_ascii(const uint8_t *str)
 {
     while (*str && *str < 128) str++;
     return !*str;
 }


> 
> 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);
> > 
> 
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