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mpv/video/decode/dec_video.h
wm4 33e5755c23 video, audio: always read all frames before getting next packet
The old code tried to make sure at all times to try to read a new
packet. Only once that was read, it tried to retrieve new video or audio
frames the decoder might already have decoded.

Change this to strictly read frames from the decoder until it signals
that it wants a new packet, and only then read and feed a new packet.
This is in theory nicer, follows the libavcodec recommended data flow,
and and reduces the minimum latency by 1 frame.

This merely requires switching the order in which those calls are done.
Normally, the decoder will return only 1 frame until a new packet is
required. If we would just feed it 1 packet, return DATA_AGAIN, and wait
until the next frame is decoded, we would run the playloop 1 time too
often for no reason (which is fine but might have some overhead). To
avoid this, try to read a frame again after possibly feeding a packet.
For this reason, move the feed/read code to its own functions each,
instead of merely moving the code.

The audio and video code for this particular thing is basically
duplicated. The idea is to unify them one day, so make the change to
both. (Doing this for video is the real motivation for this change, see
below.)

The video code change is slightly more complicated, because we have to
care about the framedrop counting (which is just a heuristic, but for
now considered better than nothing, and possibly considered required to
warn the user of framedrops happening - maybe).

Apparently this change helps with stalling streams on Android with the
mediacodec wrapper and mpeg2 decoder implementations which deinterlace on
decoding (and return 2 frames per packet).

Based on an idea and observations by tmm1.
2018-01-01 23:17:56 -08:00

102 lines
3.0 KiB
C

/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef MPLAYER_DEC_VIDEO_H
#define MPLAYER_DEC_VIDEO_H
#include <stdbool.h>
#include "demux/stheader.h"
#include "video/hwdec.h"
#include "video/mp_image.h"
struct mp_decoder_list;
struct vo;
struct dec_video {
struct mp_log *log;
struct mpv_global *global;
struct MPOpts *opts;
const struct vd_functions *vd_driver;
struct mp_hwdec_devices *hwdec_devs; // video output hwdec handles
struct sh_stream *header;
struct mp_codec_params *codec;
struct vo *vo; // required for direct rendering into video memory
char *decoder_desc;
float fps; // FPS from demuxer or from user override
int dropped_frames;
struct mp_recorder_sink *recorder_sink;
// Internal (shared with vd_lavc.c).
void *priv; // for free use by vd_driver
// Strictly internal (dec_video.c).
// Last PTS from decoder (set with each vd_driver->decode() call)
double codec_pts;
int num_codec_pts_problems;
// Last packet DTS from decoder (passed through from source packets)
double codec_dts;
int num_codec_dts_problems;
// PTS or DTS of packet first read
double first_packet_pdts;
// There was at least one packet with non-sense timestamps.
int has_broken_packet_pts; // <0: uninitialized, 0: no problems, 1: broken
int has_broken_decoded_pts;
// Final PTS of previously decoded image
double decoded_pts;
struct mp_image_params dec_format, last_format, fixed_format;
double start_pts;
double start, end;
struct demux_packet *new_segment;
struct demux_packet *packet;
bool framedrop_enabled;
bool may_decoder_framedrop;
struct mp_image *current_mpi;
int current_state;
};
struct mp_decoder_list *video_decoder_list(void);
bool video_init_best_codec(struct dec_video *d_video);
void video_uninit(struct dec_video *d_video);
void video_work(struct dec_video *d_video);
int video_get_frame(struct dec_video *d_video, struct mp_image **out_mpi);
void video_set_framedrop(struct dec_video *d_video, bool enabled);
void video_set_start(struct dec_video *d_video, double start_pts);
int video_vd_control(struct dec_video *d_video, int cmd, void *arg);
void video_reset(struct dec_video *d_video);
void video_reset_params(struct dec_video *d_video);
void video_get_dec_params(struct dec_video *d_video, struct mp_image_params *p);
#endif /* MPLAYER_DEC_VIDEO_H */