[FFmpeg-devel] [PATCH v2] libavdevice: Improve example in deprecation message for opengl and sdl

[Alexander Strasser]

On 2024-04-29 23:53 +0200, Alexander Strasser via ffmpeg-devel wrote:
> When piping ffmpeg into ffplay both programs write a status line in
> the terminal. That causes flickering and invisibility of one or the
> other status line.
>
> As compromise set ffplay log level to warning, so it doesn't show
> the status line.
>
> The user is usually testing ffmpeg command lines and want's a
> preview of the result. This way the user can see the ffmpeg output
> and still see errors and warnings from ffplay, should they occur.
>
> Additionally set PTS to zero in ffplay to lessen the delay until
> the frames are displayed. Without it delay is quite observable
> when e.g. live capturing with low frame rates.
> ---
>
> Same as previous patch, but with setpts=0 in ffplay as suggested by
> Nicolas George.
>
>
>  libavdevice/opengl_enc.c | 2 +-
>  libavdevice/sdl2.c       | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavdevice/opengl_enc.c b/libavdevice/opengl_enc.c
> index 6f7a30ff9e..93d3959880 100644
> --- a/libavdevice/opengl_enc.c
> +++ b/libavdevice/opengl_enc.c
> @@ -1067,7 +1067,7 @@ static av_cold int opengl_write_header(AVFormatContext *h)
>          av_log(opengl, AV_LOG_WARNING,
>              "The opengl output device is deprecated due to being fundamentally incompatible with libavformat API. "
>              "For monitoring purposes in ffmpeg you can output to a file or use pipes and a video player.\n"
> -            "Example: ffmpeg -i INPUT -f nut -c:v rawvideo - | ffplay -\n"
> +            "Example: ffmpeg -i INPUT -f nut -c:v rawvideo - | ffplay -loglevel warning -vf setpts=0 -\n"
>          );
>          opengl->warned = 1;
>      }
> diff --git a/libavdevice/sdl2.c b/libavdevice/sdl2.c
> index 779c8e08b0..491c8dafe8 100644
> --- a/libavdevice/sdl2.c
> +++ b/libavdevice/sdl2.c
> @@ -167,7 +167,7 @@ static int sdl2_write_header(AVFormatContext *s)
>          av_log(sdl, AV_LOG_WARNING,
>              "The sdl output device is deprecated due to being fundamentally incompatible with libavformat API. "
>              "For monitoring purposes in ffmpeg you can output to a file or use pipes and a video player.\n"
> -            "Example: ffmpeg -i INPUT -f nut -c:v rawvideo - | ffplay -\n"
> +            "Example: ffmpeg -i INPUT -f nut -c:v rawvideo - | ffplay -loglevel warning -vf setpts=0 -\n"
>          );
>          sdl->warned = 1;
>      }
> --


Will try to push soon'ish if I don't hear any objections.


  Alexander