Function av_subtitle_to_owned_subtitle_frame 

pub unsafe fn av_subtitle_to_owned_subtitle_frame(
    av_subtitle: *const AVSubtitle,
) -> Result<SubtitleFrame<SubtitleFrameExtra, FfmpegBytes>, ConvertError>

av_subtitle_to_subtitle_frame on the owned lane, which copies every byte it reads and therefore has no aliasing obligation.

Safety

The source must be live for the duration of the call.