ffmpeg中怎么编程实现获取视频中某指定的一帧？

ffmpeg中怎么编程实现获取视频中某指定的一帧？不是通过遍历，而是直接跳到指定帧，ffmpeg中有没有有相关的函数？

/**

• Seek to the keyframe at timestamp.
• 'timestamp' in 'stream_index'. *
• @param s media file handle
• @param stream_index If stream_index is (-1), a default
• stream is selected, and timestamp is automatically converted
• from AV_TIME_BASE units to the stream specific time_base.
• @param timestamp Timestamp in AVStream.time_base units
• or, if no stream is specified, in AV_TIME_BASE units.
• @param flags flags which select direction and seeking mode
• @return >= 0 on success */ int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp, int flags);