A possibly-better approach to seeking.

[dcpomatic.git] / src / lib / audio_decoder_stream.cc

diff --git a/src/lib/audio_decoder_stream.cc b/src/lib/audio_decoder_stream.cc
index b7b96ddd4ad88e17b2b03057559f283a04e617da..c14dc654e904cd611d961e4941f1356a1f8cdc17 100644 (file)
--- a/src/lib/audio_decoder_stream.cc
+++ b/src/lib/audio_decoder_stream.cc
@@ -70,17 +70,23 @@ AudioDecoderStream::get (Frame frame, Frame length, bool accurate)
 
        _log->log (String::compose ("-> ADS has request for %1 %2", frame, length), LogEntry::TYPE_DEBUG_DECODE);
 
-       Frame const end = frame + length - 1;
-
-       /* If we are less than (about) 5 seconds behind the data that we want we'll
-          run through it rather than seeking.
-       */
-       Frame const slack = 5 * 48000;
+       Frame const from = frame;
+       Frame const to = from + length;
+       Frame const have_from = _decoded.frame;
+       Frame const have_to = _decoded.frame + _decoded.audio->frames();
+
+       optional<Frame> missing;
+       if (have_from > from || have_to < to) {
+               /* We need something */
+               if (have_from < from && from < have_to) {
+                       missing = have_to;
+               } else {
+                       missing = from;
+               }
+       }
 
-       if (frame < _decoded.frame || end > (_decoded.frame + _decoded.audio->frames() + slack)) {
-               /* Either we have no decoded data, all our data is after the time that we
-                  want, or what we do have is a long way from what we want: seek */
-               _decoder->seek (ContentTime::from_frames (frame, _content->resampled_frame_rate()), accurate);
+       if (missing) {
+               _decoder->maybe_seek (ContentTime::from_frames (*missing, _content->resampled_frame_rate()), accurate);
        }
 
        /* Offset of the data that we want from the start of _decoded.audio
@@ -98,7 +104,7 @@ AudioDecoderStream::get (Frame frame, Frame length, bool accurate)
        if (accurate) {
                /* Keep stuffing data into _decoded until we have enough data, or the subclass does not want to give us any more */
                while (
-                       (_decoded.frame > frame || (_decoded.frame + _decoded.audio->frames()) < end) &&
+                       (_decoded.frame > frame || (_decoded.frame + _decoded.audio->frames()) <= to) &&
                        !_decoder->pass (Decoder::PASS_REASON_AUDIO, accurate)
                        )
                {}
@@ -106,7 +112,7 @@ AudioDecoderStream::get (Frame frame, Frame length, bool accurate)
                decoded_offset = frame - _decoded.frame;
 
                _log->log (
-                       String::compose ("Accurate ADS::get has offset %1 from request %2 and available %3", decoded_offset, frame, _decoded.frame),
+                       String::compose ("Accurate ADS::get has offset %1 from request %2 and available %3", decoded_offset, frame, have_from),
                        LogEntry::TYPE_DEBUG_DECODE
                        );
        } else {