[FFmpeg-devel] [PATCH 1/3] avformat: add AV_DISPOSITION_FRAME_BASED flag

[Clément Bœsch]

On Mon, Feb 17, 2014 at 09:49:34PM +0100, wm4 wrote:
> This is needed to distinguish subtitles with real timestamps, and
> subtitles which use frame numbers. Formats like MicroDVD can have both,
> depending on the file header.
> ---
>  doc/APIchanges         | 3 +++
>  libavformat/avformat.h | 7 +++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 047b9bd..32532ca 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil:     2012-10-22
>  
>  API changes, most recent first:
>  
> +2014-02-xx - xxxxxxx - lavf 55.33.xxx - avformat.h
> +  Add AV_DISPOSITION_FRAME_BASED flag to indicate subtitle timestamp type.
> +
>  2014-02-xx - xxxxxxx - lavd 55.10.100 - avdevice.h
>    Add avdevice_list_devices() and avdevice_free_list_devices()
>  
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index c990ad6..9491c82 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -725,6 +725,13 @@ typedef struct AVIndexEntry {
>  #define AV_DISPOSITION_METADATA     0x40000
>  
>  /**
> + * This is a frame-based subtitle format. It does not contain any real
> + * timestamps, just frame numbers. Returned AVPackets will have the pts field
> + * set to the frame number, and the stream time_base is a made-up fallback.
> + */
> +#define AV_DISPOSITION_FRAME_BASED  0x80000
> +
> +/**
>   * Options for behavior on timestamp wrap detection.
>   */
>  #define AV_PTS_WRAP_IGNORE      0   ///< ignore the wrap

OK so you prefer introducing a new symbol instead of adding a private
option the microdvd demuxer? (to read the FPS and check if it was set or
not).

I'm a bit uncomfortable adding a generic flag for just a single format;
can you find another format in the same situation? (AQTitle?)

If you can't, I'd really like to have the private option way...

(If you insist on that solution, can you update the stack of
PRINT_DISPOSITION() in ffprobe.c?)

-- 
Clément B.
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