[FFmpeg-devel] [PATCH 01/13] lavu/frame: extend AVFrame.repeat_pict documentation

[Kieran Kunhya]

On Sun, 7 May 2023, 14:34 Anton Khirnov, <anton at khirnov.net> wrote:

> ---
>  libavutil/frame.h | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index f2b56beebb..ed3f199ce1 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -491,8 +491,22 @@ typedef struct AVFrame {
>      void *opaque;
>
>      /**
> -     * When decoding, this signals how much the picture must be delayed.
> -     * extra_delay = repeat_pict / (2*fps)
> +     * Number of fields in this frame which should be repeated, i.e. the
> total
> +     * duration of this frame should be repeat_pict + 2 normal field
> durations.
> +     *
> +     * For interlaced frames this field may be set to 1, which signals
> that this
> +     * frame should be presented as 3 fields: beginning with the first
> field (as
> +     * determined by AV_FRAME_FLAG_TOP_FIELD_FIRST being set or not),
> followed
> +     * by the second field, and then the first field again.
> +     *
> +     * For progressive frames this field may be set to a multiple of 2,
> which
> +     * signals that this frame's duration should be (repeat_pict + 2) / 2
> +     * normal frame durations.


This isn't correct, a progressive [coded] frame is allowed to have its
first field repeated.

There is a difference between the coded type and the display method of a
frame. The documentation suggests otherwise.

Kieran