函数声明如下，int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)，

#define AVSEEK_FLAG_BACKWARD 1 ///< seek backward

#define AVSEEK_FLAG_BYTE     2 ///< seeking based on position in bytes

#define AVSEEK_FLAG_ANY      4 ///< seek to any frame, even non-keyframes

#define AVSEEK_FLAG_FRAME    8 ///< seeking based on frame number

代码

int f1 = 0;
const AVInputFormat* piFmt = NULL;
fmt_ctx = avformat_alloc_context();
ret = avformat_open_input(&fmt_ctx, "frag_bunny.mp4", piFmt, NULL);
while (true)
{
	Sleep(6);

	if (f1 == 0)
	{
		avformat_seek_file(fmt_ctx, 1, INT64_MIN, 40 * AV_TIME_BASE, INT64_MAX, AVSEEK_FLAG_FRAME);
		f1++;
	}

	ret = av_read_frame(fmt_ctx, &pkt);
	if (ret >= 0)
	{

		if (pkt.stream_index == video_stream_idx)
		{
			ret = decode_packet(video_dec_ctx, &pkt);
		}
		else if (pkt.stream_index == audio_stream_idx)
		{
			decodeAudio2Memory(audio_dec_ctx, &pkt, decoded_frame);
		}

		av_packet_unref(&pkt);
		if (ret < 0)
		{
			continue;
		}
	}
}

用frag_bunny.mp4文件测试seek， 40 * AV_TIME_BASE是定位到40s，但时间好像对应不上，确实跳转了，但并非在第40s，AVSEEK_FLAG_BACKWARD和AVSEEK_FLAG_FRAME可以解码显示，

另外两个不可以