[FFmpeg-devel] [PATCH] Add channel label and bitmap values to metadata

[Michael Niedermayer]

On Fri, Oct 10, 2014 at 11:21:23AM +0100, Billy Shambrook wrote:
> ---
>  libavformat/mov_chan.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 75 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/mov_chan.c b/libavformat/mov_chan.c
> index 3b91ed7..aa369f2 100644
> --- a/libavformat/mov_chan.c
> +++ b/libavformat/mov_chan.c
> @@ -133,6 +133,66 @@ enum MovChannelLayoutTag {
>      MOV_CH_LAYOUT_DTS_8_1_B             = (181 << 16) | 9,
>  };
>  
> +struct MovChannelLabel {
> +    uint32_t code;
> +    char name[128];
> +};
> +
> +static const struct MovChannelLabel mov_ch_labels[] = {
> +    { 0,            "Unused"              },
> +    { 1,            "Left"                },
> +    { 2,            "Right"               },
> +    { 3,            "Center"              },
> +    { 4,            "LFE Screen"          },
> +    { 5,            "Left Surround"       },
> +    { 6,            "Right Surround"      },
> +    { 7,            "Left Center"         },
> +    { 8,            "Right Center"        },
> +    { 9,            "Center Surround"     },
> +    { 33,           "Rear Surround Left"  },
> +    { 34,           "Rear Surround Right" },
> +    { 38,           "Left Total"          },
> +    { 39,           "Right Total"         },
> +    { 42,           "Mono"                },
> +    { 65536,        "Discrete 0"          },
> +    { (1<<16) | 1,  "Discrete 1"          },
> +    { (1<<16) | 2,  "Discrete 2"          },
> +    { (1<<16) | 3,  "Discrete 3"          },
> +    { (1<<16) | 4,  "Discrete 4"          },
> +    { (1<<16) | 5,  "Discrete 5"          },
> +    { (1<<16) | 6,  "Discrete 6"          },
> +    { (1<<16) | 7,  "Discrete 7"          },
> +    { (1<<16) | 8,  "Discrete 8"          },
> +    { (1<<16) | 9,  "Discrete 9"          },
> +    { (1<<16) | 10, "Discrete 10"         },
> +    { (1<<16) | 11, "Discrete 11"         },
> +    { (1<<16) | 12, "Discrete 12"         },
> +    { (1<<16) | 13, "Discrete 13"         },
> +    { (1<<16) | 14, "Discrete 14"         },
> +    { (1<<16) | 15, "Discrete 15"         },
> +    { 0xFFFFFFFF,   "Unknown"             }
> +};
> +
> +struct MovChannelBitmap {
> +    uint32_t code;
> +    char name[128];
> +};
> +
> +static const struct MovChannelBitmap mov_ch_bitmap[] = {
> +    { (1 << 0),   "Left"                 },
> +    { (1 << 1),   "Right"                },
> +    { (1 << 2),   "Center"               },
> +    { (1 << 3),   "LFE Screen"           },
> +    { (1 << 4),   "Left Surround"        },
> +    { (1 << 5),   "Right Surround"       },
> +    { (1 << 6),   "Left Center"          },
> +    { (1 << 7),   "Right Center"         },
> +    { (1 << 8),   "Center Surround"      },
> +    { (1 << 9),   "Left Surround Direct" },
> +    { (1 << 10),  "Rear Surround Direct" },
> +    { 0xFFFFFFFF, "Unknown"              }
> +};
> +
>  struct MovChannelLayoutMap {
>      uint32_t tag;
>      uint64_t layout;
> @@ -548,7 +608,8 @@ int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st,
>                       int64_t size)
>  {
>      uint32_t layout_tag, bitmap, num_descr, label_mask;
> -    int i;
> +    int i, j;
> +    char label_tag[16];
>  
>      if (size < 12)
>          return AVERROR_INVALIDDATA;
> @@ -572,6 +633,13 @@ int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st,
>          avio_rl32(pb);                      // mCoordinates[1]
>          avio_rl32(pb);                      // mCoordinates[2]
>          size -= 20;
> +        for (j = 0; mov_ch_labels[j].code != 0xFFFFFFFF; j++) {
> +            if (mov_ch_labels[j].code == label){
> +                snprintf(label_tag, sizeof(label_tag), "channel_label_%d", i);
> +                av_dict_set(&st->metadata, label_tag, mov_ch_labels[j].name, 0);
> +                break;
> +            }
> +        }
>          if (layout_tag == 0) {
>              uint32_t mask_incr = mov_get_channel_label(label);
>              if (mask_incr == 0) {

    > @@ -585,6 +653,12 @@ int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st,
>          if (label_mask)
>              st->codec->channel_layout = label_mask;
>      } else
> +        for (i = 0; mov_ch_bitmap[i].code != 0xFFFFFFFF; i++) {
> +            if (mov_ch_bitmap[i].code == bitmap){
> +                av_dict_set(&st->metadata, "channel_bitmap", mov_ch_bitmap[i].name, 0);
> +                break;
> +            }
> +        }
>          st->codec->channel_layout = ff_mov_get_channel_layout(layout_tag, bitmap);

missing {}

also the metadata has to be discarded if the channel layout is
changed in a filter as it would no longer match but 
would be stored in the destination file

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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