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authorwm4 <wm4@nowhere>2015-12-18 00:51:57 +0100
committerwm4 <wm4@nowhere>2015-12-18 03:52:57 +0100
commit2c7db48195b03e93ee3cbf382ccabcedb96a6830 (patch)
tree165c6d52549991bf6c03cd47e495a558f14ac4ce /sub/sd_ass.c
parent7137afeb2c466135ab0e01ee0f9cbd2abd000563 (diff)
downloadmpv-2c7db48195b03e93ee3cbf382ccabcedb96a6830.tar.bz2
mpv-2c7db48195b03e93ee3cbf382ccabcedb96a6830.tar.xz
sub: do not clear subtitle list on seeking
This affects non-ASS text subtitles (those which go through libavcodec's subtitle converter), which are muxed with video/audio. (Typically srt subs in mkv.) The problem is that seeking in the file can send a subtitle packet to the decoder multiple times. These packets are interlaved with video, and thus can't be all read when opening the file. Rather, subtitle packets can essentially be randomly skipped or repeated (by seeking). Until recently, this was solved by scanning the libass event list for duplicates. Then our builtin srt-to-ass converter was removed, and the problem was handled by fully clearing the subtitle list on each seek. This resulted in sub-seek not working properly for this type of file. Since the subtitle list was cleared on seek, it was not possible to do e.g. sub-seeks to subtitles before the current playback position. Fix this by not clearing the list, and intead explicitly rejecting duplicate packets. We use the packet file position was unique ID for subtitles; this is confirmed working for most file formats (although it is slightly risky - new demuxers may not necessarily set the file position to something unique, or at all). The list of seen packets is sorted, and the lookup uses binary search. This is to avoid quadratic complexity when subtitles are added in bulks, such as when opening a text subtitle file. In some places, the code has to be adjusted to pass through the packet file position correctly.
Diffstat (limited to 'sub/sd_ass.c')
-rw-r--r--sub/sd_ass.c50
1 files changed, 33 insertions, 17 deletions
diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index 4c6296b2f4..dc045996cd 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -42,11 +42,12 @@ struct sd_ass_priv {
bool is_converted;
bool on_top;
struct sub_bitmap *parts;
- bool flush_on_seek;
char last_text[500];
struct mp_image_params video_params;
struct mp_image_params last_params;
double sub_speed;
+ int64_t *seen_packets;
+ int num_seen_packets;
};
static void mangle_colors(struct sd *sd, struct sub_bitmaps *parts);
@@ -130,19 +131,42 @@ static int init(struct sd *sd)
return 0;
}
+// Test if the packet with the given file position (used as unique ID) was
+// already consumed. Return false if the packet is new (and add it to the
+// internal list), and return true if it was already seen.
+static bool check_packet_seen(struct sd *sd, int64_t pos)
+{
+ struct sd_ass_priv *priv = sd->priv;
+ int a = 0;
+ int b = priv->num_seen_packets;
+ while (a < b) {
+ int mid = a + (b - a) / 2;
+ int64_t val = priv->seen_packets[mid];
+ if (pos == val)
+ return true;
+ if (pos > val) {
+ a = mid + 1;
+ } else {
+ b = mid;
+ }
+ }
+ MP_TARRAY_INSERT_AT(priv, priv->seen_packets, priv->num_seen_packets, a, pos);
+ return false;
+}
+
static void decode(struct sd *sd, struct demux_packet *packet)
{
struct sd_ass_priv *ctx = sd->priv;
ASS_Track *track = ctx->ass_track;
if (strcmp(sd->codec, "ass") == 0) {
- long long ipts = lrint(packet->pts * 1000);
- long long iduration = lrint(packet->duration * 1000);
- ass_process_chunk(track, packet->buffer, packet->len, ipts, iduration);
- return;
+ // Note that for this packet format, libass has an internal mechanism
+ // for discarding duplicate (already seen) packets.
+ ass_process_chunk(track, packet->buffer, packet->len,
+ lrint(packet->pts * 1000),
+ lrint(packet->duration * 1000));
} else {
- // "ssa" codec ID
- ctx->flush_on_seek = true;
- ass_process_data(track, packet->buffer, packet->len);
+ if (!check_packet_seen(sd, packet->pos))
+ ass_process_data(track, packet->buffer, packet->len);
}
}
@@ -476,18 +500,11 @@ static void fill_plaintext(struct sd *sd, double pts)
track->styles[track->default_style].Alignment = ctx->on_top ? 6 : 2;
}
-static void fix_events(struct sd *sd)
-{
- struct sd_ass_priv *ctx = sd->priv;
- ctx->flush_on_seek = false;
-}
-
static void reset(struct sd *sd)
{
struct sd_ass_priv *ctx = sd->priv;
- if (ctx->flush_on_seek || sd->opts->sub_clear_on_seek)
+ if (sd->opts->sub_clear_on_seek)
ass_flush_events(ctx->ass_track);
- ctx->flush_on_seek = false;
}
static void uninit(struct sd *sd)
@@ -530,7 +547,6 @@ const struct sd_functions sd_ass = {
.decode = decode,
.get_bitmaps = get_bitmaps,
.get_text = get_text,
- .fix_events = fix_events,
.control = control,
.reset = reset,
.uninit = uninit,