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mpv/sub/sd.h
wm4 4a8647b6b8 sub: don't potentially discard too many subtitles on seek
The accepts_packet packet callback is supposed to deal with subtitle
decoders which have only a small queue of current subtitle events (i.e.
sd_lavc.c), in case feeding it too many packets would discard events
that are still needed.

Normally, the number of subtitles that need to be preserved is estimated
by the rendering pts (get_bitmaps() argument). Rendering lags behind
decoding, so normally the rendering pts is smaller than the next video
frame pts, and we simply discard all subtitle events until the rendering
pts.

This breaks down in some annoying corner cases. One of them is seeking
backwards: the VO will still try to render the old PTS during seeks,
which passes a high PTS to the subtitle renderer, which in turn would
discard more subtitles than it should. There is a similar issue with
forward seeks. Add hacks to deal with those issues.

There should be a better way to deal with the essentially unknown
"rendering position", which is made worse by screenshots or rendering
with vf_sub. At the very least, we could handle seeks better, and e.g.
either force the VO not to re-render subs after seeks (ugly), or
introduce seek sequence numbers to distinguish attempts to render
earlier subtitles when a seek is done.
2016-08-14 20:27:37 +02:00

54 lines
1.6 KiB
C

#ifndef MPLAYER_SD_H
#define MPLAYER_SD_H
#include "dec_sub.h"
#include "demux/packet.h"
// up to 210 ms overlaps or gaps are removed
#define SUB_GAP_THRESHOLD 0.210
// don't change timings if durations are smaller
#define SUB_GAP_KEEP 0.4
struct sd {
struct mpv_global *global;
struct mp_log *log;
struct MPOpts *opts;
const struct sd_functions *driver;
void *priv;
struct attachment_list *attachments;
struct mp_codec_params *codec;
// Set to false as soon as the decoder discards old subtitle events.
// (only needed if sd_functions.accept_packets_in_advance == false)
bool preload_ok;
};
struct sd_functions {
const char *name;
bool accept_packets_in_advance;
int (*init)(struct sd *sd);
void (*decode)(struct sd *sd, struct demux_packet *packet);
void (*reset)(struct sd *sd);
void (*select)(struct sd *sd, bool selected);
void (*uninit)(struct sd *sd);
bool (*accepts_packet)(struct sd *sd, double pts); // implicit default if NULL: true
int (*control)(struct sd *sd, enum sd_ctrl cmd, void *arg);
void (*get_bitmaps)(struct sd *sd, struct mp_osd_res dim, int format,
double pts, struct sub_bitmaps *res);
char *(*get_text)(struct sd *sd, double pts);
};
struct lavc_conv;
struct lavc_conv *lavc_conv_create(struct mp_log *log, const char *codec_name,
char *extradata, int extradata_len);
char *lavc_conv_get_extradata(struct lavc_conv *priv);
char **lavc_conv_decode(struct lavc_conv *priv, struct demux_packet *packet);
void lavc_conv_reset(struct lavc_conv *priv);
void lavc_conv_uninit(struct lavc_conv *priv);
#endif