[FFmpeg-devel] [PATCH 1/7] avutil/channel_layout: add AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL

[Marton Balint]

On Sat, 9 Mar 2024, Marton Balint wrote:

> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/APIchanges             |  3 +++
> libavutil/channel_layout.c | 30 ++++++++++++++++++++++++++++++
> libavutil/channel_layout.h |  7 +++++++
> libavutil/version.h        |  2 +-
> 4 files changed, 41 insertions(+), 1 deletion(-)

Will apply the series.

Regards,
Marton

>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index cf58c8c5f0..a44c8e4f10 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -2,6 +2,9 @@ The last version increases of all libraries were on 2024-03-07
>
> API changes, most recent first:
>
> +2024-03-xx - xxxxxxxxxx - lavu 59.2.100 - channel_layout.h
> +  Add AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL.
> +
> 2024-03-08 - xxxxxxxxxx - lavc 61.1.100 - avcodec.h
>   Add AVCodecContext.[nb_]side_data_prefer_packet.
>
> diff --git a/libavutil/channel_layout.c b/libavutil/channel_layout.c
> index 8c1b3362f7..d3abb2dc42 100644
> --- a/libavutil/channel_layout.c
> +++ b/libavutil/channel_layout.c
> @@ -553,6 +553,33 @@ static int ambisonic_order(const AVChannelLayout *channel_layout)
>     return order;
> }
>
> +static enum AVChannelOrder canonical_order(AVChannelLayout *channel_layout)
> +{
> +    int has_known_channel = 0;
> +    int order;
> +
> +    if (channel_layout->order != AV_CHANNEL_ORDER_CUSTOM)
> +        return channel_layout->order;
> +
> +    if (has_channel_names(channel_layout))
> +        return AV_CHANNEL_ORDER_CUSTOM;
> +
> +    for (int i = 0; i < channel_layout->nb_channels && !has_known_channel; i++)
> +        if (channel_layout->u.map[i].id != AV_CHAN_UNKNOWN)
> +            has_known_channel = 1;
> +    if (!has_known_channel)
> +        return AV_CHANNEL_ORDER_UNSPEC;
> +
> +    if (masked_description(channel_layout, 0) > 0)
> +        return AV_CHANNEL_ORDER_NATIVE;
> +
> +    order = ambisonic_order(channel_layout);
> +    if (order >= 0 && masked_description(channel_layout, (order + 1) * (order + 1)) >= 0)
> +        return AV_CHANNEL_ORDER_AMBISONIC;
> +
> +    return AV_CHANNEL_ORDER_CUSTOM;
> +}
> +
> /**
>  * If the custom layout is n-th order standard-order ambisonic, with optional
>  * extra non-diegetic channels at the end, write its string description in bp.
> @@ -892,6 +919,9 @@ int av_channel_layout_retype(AVChannelLayout *channel_layout, enum AVChannelOrde
>     if (!av_channel_layout_check(channel_layout))
>         return AVERROR(EINVAL);
>
> +    if (flags & AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL)
> +        order = canonical_order(channel_layout);
> +
>     if (channel_layout->order == order)
>         return 0;
>
> diff --git a/libavutil/channel_layout.h b/libavutil/channel_layout.h
> index 10ffe74468..a1e9b08064 100644
> --- a/libavutil/channel_layout.h
> +++ b/libavutil/channel_layout.h
> @@ -680,6 +680,13 @@ int av_channel_layout_compare(const AVChannelLayout *chl, const AVChannelLayout
>  */
> #define AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS (1 << 0)
>
> +/**
> + * The specified retype target order is ignored and the simplest possible
> + * (canonical) order is used for which the input layout can be losslessy
> + * represented.
> + */
> +#define AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL (1 << 1)
> +
> /**
>  * Change the AVChannelOrder of a channel layout.
>  *
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 09f8cdc292..57cad02ec0 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>  */
>
> #define LIBAVUTIL_VERSION_MAJOR  59
> -#define LIBAVUTIL_VERSION_MINOR   1
> +#define LIBAVUTIL_VERSION_MINOR   2
> #define LIBAVUTIL_VERSION_MICRO 100
>
> #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
> -- 
> 2.35.3
>
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