+optional<ContentVideo>
+VideoDecoder::decoded_video (VideoFrame frame)
+{
+ for (list<ContentVideo>::const_iterator i = _decoded_video.begin(); i != _decoded_video.end(); ++i) {
+ if (i->frame == frame) {
+ return *i;
+ }
+ }
+
+ return optional<ContentVideo> ();
+}
+
+optional<ContentVideo>
+VideoDecoder::get_video (VideoFrame frame, bool accurate)
+{
+ if (_decoded_video.empty() || (frame < _decoded_video.front().frame || frame > (_decoded_video.back().frame + 1))) {
+ /* Either we have no decoded data, or what we do have is a long way from what we want: seek */
+ seek (ContentTime::from_frames (frame, _video_content->video_frame_rate()), accurate);
+ }
+
+ optional<ContentVideo> dec;
+
+ /* Now enough pass() calls should either:
+ * (a) give us what we want, or
+ * (b) hit the end of the decoder.
+ */
+ if (accurate) {
+ /* We are being accurate, so we want the right frame.
+ * This could all be one statement but it's split up for clarity.
+ */
+ while (true) {
+ if (decoded_video (frame)) {
+ /* We got what we want */
+ break;
+ }
+
+ if (pass ()) {
+ /* The decoder has nothing more for us */
+ break;
+ }
+
+ if (!_decoded_video.empty() && _decoded_video.front().frame > frame) {
+ /* We're never going to get the frame we want. Perhaps the caller is asking
+ * for a video frame before the content's video starts (if its audio
+ * begins before its video, for example).
+ */
+ break;
+ }
+ }
+
+ dec = decoded_video (frame);
+ } else {
+ /* Any frame will do: use the first one that comes out of pass() */
+ while (_decoded_video.empty() && !pass ()) {}
+ if (!_decoded_video.empty ()) {
+ dec = _decoded_video.front ();
+ }
+ }
+
+ /* Clean up decoded_video */
+ while (!_decoded_video.empty() && _decoded_video.front().frame < (frame - 1)) {
+ _decoded_video.pop_front ();
+ }
+
+ return dec;
+}
+
+