[FFmpeg-devel] [PATCH 7/7] avcodec/aacdec_template: add support for 22.2 / channel_config 13

[Michael Niedermayer]

On Sat, Aug 01, 2020 at 02:07:30PM +0300, Jan Ekström wrote:
> ---
>  libavcodec/aacdec_template.c | 89 +++++++++++++++++++++++++++++++-----
>  1 file changed, 78 insertions(+), 11 deletions(-)
> 
> diff --git a/libavcodec/aacdec_template.c b/libavcodec/aacdec_template.c
> index 21db12fdab..8c5048cc13 100644
> --- a/libavcodec/aacdec_template.c
> +++ b/libavcodec/aacdec_template.c
> @@ -387,17 +387,77 @@ static uint64_t sniff_channel_order(uint8_t (*layout_map)[3], int tags)
>          i++;
>      }
>  
> -    // Must choose a stable sort
> +    // The previous checks would end up at 8 at this point for 22.2
> +    if (tags == 16 && i == 8) {
> +        e2c_vec[i] = (struct elem_to_channel) {
> +            .av_position  = AV_CH_TOP_FRONT_CENTER,
> +            .syn_ele      = layout_map[i][0],
> +            .elem_id      = layout_map[i][1],
> +            .aac_position = layout_map[i][2]
> +        }; i++;
> +        i += assign_pair(e2c_vec, layout_map, i,
> +                         AV_CH_TOP_FRONT_LEFT,
> +                         AV_CH_TOP_FRONT_RIGHT,
> +                         AAC_CHANNEL_FRONT);
> +        i += assign_pair(e2c_vec, layout_map, i,
> +                         AV_CH_TOP_SIDE_LEFT,
> +                         AV_CH_TOP_SIDE_RIGHT,
> +                         AAC_CHANNEL_SIDE);
> +        e2c_vec[i] = (struct elem_to_channel) {
> +            .av_position  = AV_CH_TOP_CENTER,
> +            .syn_ele      = layout_map[i][0],
> +            .elem_id      = layout_map[i][1],
> +            .aac_position = layout_map[i][2]
> +        }; i++;
> +        i += assign_pair(e2c_vec, layout_map, i,
> +                         AV_CH_TOP_BACK_LEFT,
> +                         AV_CH_TOP_BACK_RIGHT,
> +                         AAC_CHANNEL_BACK);
> +        e2c_vec[i] = (struct elem_to_channel) {
> +            .av_position  = AV_CH_TOP_BACK_CENTER,
> +            .syn_ele      = layout_map[i][0],

Does this code assume all types are CPE ?
because if thats not true i can exceed the tags


> +            .elem_id      = layout_map[i][1],
> +            .aac_position = layout_map[i][2]
> +        }; i++;
> +        e2c_vec[i] = (struct elem_to_channel) {
> +            .av_position  = AV_CH_BOTTOM_FRONT_CENTER,
> +            .syn_ele      = layout_map[i][0],
> +            .elem_id      = layout_map[i][1],
> +            .aac_position = layout_map[i][2]
> +        }; i++;
> +        i += assign_pair(e2c_vec, layout_map, i,
> +                         AV_CH_BOTTOM_FRONT_LEFT,
> +                         AV_CH_BOTTOM_FRONT_RIGHT,
> +                         AAC_CHANNEL_FRONT);
> +    }
> +
>      total_non_cc_elements = n = i;
> -    do {
> -        int next_n = 0;
> -        for (i = 1; i < n; i++)
> -            if (e2c_vec[i - 1].av_position > e2c_vec[i].av_position) {
> -                FFSWAP(struct elem_to_channel, e2c_vec[i - 1], e2c_vec[i]);
> -                next_n = i;
> -            }
> -        n = next_n;
> -    } while (n > 0);
> +
> +    if (tags == 16 && total_non_cc_elements == 16) {
> +        // For 22.2 reorder the result as needed
> +        FFSWAP(struct elem_to_channel, e2c_vec[2], e2c_vec[0]);   // FL & FR first (final), FC third
> +        FFSWAP(struct elem_to_channel, e2c_vec[2], e2c_vec[1]);   // FC second (final), FLc & FRc third
> +        FFSWAP(struct elem_to_channel, e2c_vec[6], e2c_vec[2]);   // LFE1 third (final), FLc & FRc seventh
> +        FFSWAP(struct elem_to_channel, e2c_vec[4], e2c_vec[3]);   // BL & BR fourth (final), SiL & SiR fifth
> +        FFSWAP(struct elem_to_channel, e2c_vec[6], e2c_vec[4]);   // FLc & FRc fifth (final), SiL & SiR seventh
> +        FFSWAP(struct elem_to_channel, e2c_vec[7], e2c_vec[6]);   // LFE2 seventh (final), SiL & SiR eight (final)
> +        FFSWAP(struct elem_to_channel, e2c_vec[9], e2c_vec[8]);   // TpFL & TpFR ninth (final), TFC tenth (final)
> +        FFSWAP(struct elem_to_channel, e2c_vec[11], e2c_vec[10]); // TC eleventh (final), TpSiL & TpSiR twelth
> +        FFSWAP(struct elem_to_channel, e2c_vec[12], e2c_vec[11]); // TpBL & TpBR twelth (final), TpSiL & TpSiR thirteenth (final)

Does this not need to check the assumtations from the comments ?

thx

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

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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