[FFmpeg-devel] [PATCH] avformat/options_table, doc/formats: clarify meaning of igndts as per definition in avformat.h

[Stefano Sabatini]

On date Saturday 2023-12-09 21:05:13 -0600, Marth64 wrote:
> This confused me for a long time, hopefully this is helpful to others.
> The definition in avformat.h says "Ignore DTS on frames that contain both DTS & PTS"
> 
> Signed-off-by: Marth64 <marth64 at proxyid.net>
> ---
>  doc/formats.texi            | 2 +-
>  libavformat/options_table.h | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/formats.texi b/doc/formats.texi
> index 640b23b790..2ebcef50c0 100644
> --- a/doc/formats.texi
> +++ b/doc/formats.texi
> @@ -46,7 +46,7 @@ Enable fast, but inaccurate seeks for some formats.
>  @item genpts
>  Generate missing PTS if DTS is present.
>  @item igndts
> -Ignore DTS if PTS is set. Inert when nofillin is set.
> +Ignore DTS if PTS is also set. Inert when nofillin is set.

This can be expanded a bit, my take:

Ignore DTS if PTS is also set. In case the PTS is set, the DTS value
is set to NOPTS. This is ignored when the @code{nofillin} flag is set.

>  @item ignidx
>  Ignore index.
>  @item nobuffer
> diff --git a/libavformat/options_table.h b/libavformat/options_table.h
> index 91708de453..4ee3fc1d81 100644
> --- a/libavformat/options_table.h
> +++ b/libavformat/options_table.h
> @@ -45,7 +45,7 @@ static const AVOption avformat_options[] = {
>  {"genpts", "generate pts", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_GENPTS }, INT_MIN, INT_MAX, D, "fflags"},
>  {"nofillin", "do not fill in missing values that can be exactly calculated", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOFILLIN }, INT_MIN, INT_MAX, D, "fflags"},
>  {"noparse", "disable AVParsers, this needs nofillin too", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOPARSE }, INT_MIN, INT_MAX, D, "fflags"},
> -{"igndts", "ignore dts", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_IGNDTS }, INT_MIN, INT_MAX, D, "fflags"},

> +{"igndts", "ignore dts (if pts is also set)", 0, AV_OPT_TYPE_CONST,
>  {.i64 = AVFMT_FLAG_IGNDTS }, INT_MIN, INT_MAX, D, "fflags"},

set DTS to NOPTS value in case PTS is set
?