Hi,

If we try to extract audio from an .mp3 file starting from a point that is
beyond its total duration with command:
*./ffmpeg -ss 600 -i eye.mp3 -c:a libopus output.opus*

We should hit this if statement in libavformat/seek.c:
if (min_ts > ts || max_ts < ts)
return -1;

But if the file's metadata are corrupted then min_ts and max_ts will not be
the correct ones. min_ts and max_ts take the values of the metadata
durations of the file.

By adding the following check, we make sure that we return an error even if
the metadata is corrupted:
if (ts > s->duration) {
av_log(NULL, AV_LOG_ERROR, "Seek position (%d) is larger than file duration
(%d). Exiting...\n", ts, s->duration);
return AVERROR_INVALIDDATA;
}

This is my first patch submission. Please let me know if any modifications
are needed.

Thanks,
bayesiandog