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b74c09efbf
mpv/player/video.c
wm4 b74c09efbf audio: refactor how data is passed to AO 
This replaces the two buffers (ao_chain.ao_buffer in the core, and
buffer_state.buffers in the AO) with a single queue. Instead of having a
byte based buffer, the queue is simply a list of audio frames, as output
by the decoder. This should make dataflow simpler and reduce copying.

It also attempts to simplify fill_audio_out_buffers(), the function I
always hated most, because it's full of subtle and buggy logic.

Unfortunately, I got assaulted by corner cases, dumb features (attempt
at seamless looping, really?), and other crap, so it got pretty
complicated again. fill_audio_out_buffers() is still full of subtle and
buggy logic. Maybe it got worse. On the other hand, maybe there really
is some progress. Who knows.

Originally, the data flow parts was meant to be in f_output_chain, but
due to tricky interactions with the playloop code, it's now in the dummy
filter in audio.c.

At least this improves the way the audio PTS is passed to the encoder in
encoding mode. Now it attempts to pass frames directly, along with the
pts, which should minimize timestamp problems. But to be honest, encoder
mode is one big kludge that shouldn't exist in this way.

This commit should be considered pre-alpha code. There are lots of bugs
still hiding.
2020-08-29 13:12:32 +02:00

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/*
* 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/>.
*/
#include <stddef.h>
#include <stdbool.h>
#include <inttypes.h>
#include <math.h>
#include <assert.h>
#include "config.h"
#include "mpv_talloc.h"
#include "common/msg.h"
#include "options/options.h"
#include "options/m_config.h"
#include "options/m_option.h"
#include "common/common.h"
#include "common/encode.h"
#include "options/m_property.h"
#include "osdep/timer.h"
#include "audio/out/ao.h"
#include "audio/format.h"
#include "demux/demux.h"
#include "stream/stream.h"
#include "sub/osd.h"
#include "video/hwdec.h"
#include "filters/f_decoder_wrapper.h"
#include "video/out/vo.h"
#include "core.h"
#include "command.h"
#include "screenshot.h"
enum {
// update_video() - code also uses: <0 error, 0 eof, >0 progress
VD_ERROR = -1,
VD_EOF = 0, // end of file - no new output
VD_PROGRESS = 1, // progress, but no output; repeat call with no waiting
VD_NEW_FRAME = 2, // the call produced a new frame
VD_WAIT = 3, // no EOF, but no output; wait until wakeup
};
static const char av_desync_help_text[] =
"\n"
"Audio/Video desynchronisation detected! Possible reasons include too slow\n"
"hardware, temporary CPU spikes, broken drivers, and broken files. Audio\n"
"position will not match to the video (see A-V status field).\n"
"\n";
static bool recreate_video_filters(struct MPContext *mpctx)
{
struct MPOpts *opts = mpctx->opts;
struct vo_chain *vo_c = mpctx->vo_chain;
assert(vo_c);
return mp_output_chain_update_filters(vo_c->filter, opts->vf_settings);
}
int reinit_video_filters(struct MPContext *mpctx)
{
struct vo_chain *vo_c = mpctx->vo_chain;
if (!vo_c)
return 0;
if (!recreate_video_filters(mpctx))
return -1;
mp_force_video_refresh(mpctx);
mp_notify(mpctx, MPV_EVENT_VIDEO_RECONFIG, NULL);
return 0;
}
static void vo_chain_reset_state(struct vo_chain *vo_c)
{
vo_seek_reset(vo_c->vo);
vo_c->underrun = false;
vo_c->underrun_signaled = false;
}
void reset_video_state(struct MPContext *mpctx)
{
if (mpctx->vo_chain) {
vo_chain_reset_state(mpctx->vo_chain);
struct track *t = mpctx->vo_chain->track;
if (t && t->dec)
mp_decoder_wrapper_set_play_dir(t->dec, mpctx->play_dir);
}
for (int n = 0; n < mpctx->num_next_frames; n++)
mp_image_unrefp(&mpctx->next_frames[n]);
mpctx->num_next_frames = 0;
mp_image_unrefp(&mpctx->saved_frame);
mpctx->delay = 0;
mpctx->time_frame = 0;
mpctx->video_pts = MP_NOPTS_VALUE;
mpctx->last_frame_duration = 0;
mpctx->num_past_frames = 0;
mpctx->total_avsync_change = 0;
mpctx->last_av_difference = 0;
mpctx->mistimed_frames_total = 0;
mpctx->drop_message_shown = 0;
mpctx->display_sync_drift_dir = 0;
mpctx->video_status = mpctx->vo_chain ? STATUS_SYNCING : STATUS_EOF;
}
void uninit_video_out(struct MPContext *mpctx)
{
uninit_video_chain(mpctx);
if (mpctx->video_out) {
vo_destroy(mpctx->video_out);
mp_notify(mpctx, MPV_EVENT_VIDEO_RECONFIG, NULL);
}
mpctx->video_out = NULL;
}
static void vo_chain_uninit(struct vo_chain *vo_c)
{
struct track *track = vo_c->track;
if (track) {
assert(track->vo_c == vo_c);
track->vo_c = NULL;
if (vo_c->dec_src)
assert(track->dec->f->pins[0] == vo_c->dec_src);
talloc_free(track->dec->f);
track->dec = NULL;
}
if (vo_c->filter_src)
mp_pin_disconnect(vo_c->filter_src);
talloc_free(vo_c->filter->f);
talloc_free(vo_c);
// this does not free the VO
}
void uninit_video_chain(struct MPContext *mpctx)
{
if (mpctx->vo_chain) {
reset_video_state(mpctx);
vo_chain_uninit(mpctx->vo_chain);
mpctx->vo_chain = NULL;
mpctx->video_status = STATUS_EOF;
mp_notify(mpctx, MPV_EVENT_VIDEO_RECONFIG, NULL);
}
}
int init_video_decoder(struct MPContext *mpctx, struct track *track)
{
assert(!track->dec);
if (!track->stream)
goto err_out;
struct mp_filter *parent = mpctx->filter_root;
// If possible, set this as parent so the decoder gets the hwdec and DR
// interfaces.
// Note: at least mpv_opengl_cb_uninit_gl() relies on being able to get
// rid of all references to the VO by destroying the VO chain. Thus,
// decoders not linked to vo_chain must not use the hwdec context.
if (track->vo_c)
parent = track->vo_c->filter->f;
track->dec = mp_decoder_wrapper_create(parent, track->stream);
if (!track->dec)
goto err_out;
if (!mp_decoder_wrapper_reinit(track->dec))
goto err_out;
return 1;
err_out:
if (track->sink)
mp_pin_disconnect(track->sink);
track->sink = NULL;
error_on_track(mpctx, track);
return 0;
}
void reinit_video_chain(struct MPContext *mpctx)
{
struct track *track = mpctx->current_track[0][STREAM_VIDEO];
if (!track || !track->stream) {
error_on_track(mpctx, track);
return;
}
reinit_video_chain_src(mpctx, track);
}
static void filter_update_subtitles(void *ctx, double pts)
{
struct MPContext *mpctx = ctx;
if (osd_get_render_subs_in_filter(mpctx->osd))
update_subtitles(mpctx, pts);
}
// (track=NULL creates a blank chain, used for lavfi-complex)
void reinit_video_chain_src(struct MPContext *mpctx, struct track *track)
{
assert(!mpctx->vo_chain);
if (!mpctx->video_out) {
struct vo_extra ex = {
.input_ctx = mpctx->input,
.osd = mpctx->osd,
.encode_lavc_ctx = mpctx->encode_lavc_ctx,
.wakeup_cb = mp_wakeup_core_cb,
.wakeup_ctx = mpctx,
};
mpctx->video_out = init_best_video_out(mpctx->global, &ex);
if (!mpctx->video_out) {
MP_FATAL(mpctx, "Error opening/initializing "
"the selected video_out (--vo) device.\n");
mpctx->error_playing = MPV_ERROR_VO_INIT_FAILED;
goto err_out;
}
mpctx->mouse_cursor_visible = true;
}
update_window_title(mpctx, true);
struct vo_chain *vo_c = talloc_zero(NULL, struct vo_chain);
mpctx->vo_chain = vo_c;
vo_c->log = mpctx->log;
vo_c->vo = mpctx->video_out;
vo_c->filter =
mp_output_chain_create(mpctx->filter_root, MP_OUTPUT_CHAIN_VIDEO);
mp_output_chain_set_vo(vo_c->filter, vo_c->vo);
vo_c->filter->update_subtitles = filter_update_subtitles;
vo_c->filter->update_subtitles_ctx = mpctx;
if (track) {
vo_c->track = track;
track->vo_c = vo_c;
if (!init_video_decoder(mpctx, track))
goto err_out;
vo_c->dec_src = track->dec->f->pins[0];
vo_c->filter->container_fps =
mp_decoder_wrapper_get_container_fps(track->dec);
vo_c->is_coverart = !!track->stream->attached_picture;
vo_c->is_sparse = track->stream->still_image || vo_c->is_coverart;
track->vo_c = vo_c;
vo_c->track = track;
mp_pin_connect(vo_c->filter->f->pins[0], vo_c->dec_src);
}
if (!recreate_video_filters(mpctx))
goto err_out;
update_screensaver_state(mpctx);
vo_set_paused(vo_c->vo, get_internal_paused(mpctx));
// If we switch on video again, ensure audio position matches up.
if (mpctx->ao_chain && mpctx->ao_chain->ao) {
ao_reset(mpctx->ao_chain->ao);
mpctx->ao_chain->start_pts_known = false;
mpctx->audio_status = STATUS_SYNCING;
}
reset_video_state(mpctx);
reset_subtitle_state(mpctx);
return;
err_out:
uninit_video_chain(mpctx);
error_on_track(mpctx, track);
handle_force_window(mpctx, true);
}
// Try to refresh the video by doing a precise seek to the currently displayed
// frame. This can go wrong in all sorts of ways, so use sparingly.
void mp_force_video_refresh(struct MPContext *mpctx)
{
struct MPOpts *opts = mpctx->opts;
struct vo_chain *vo_c = mpctx->vo_chain;
if (!vo_c)
return;
// If not paused, the next frame should come soon enough.
if (opts->pause || mpctx->time_frame >= 0.5 ||
mpctx->video_status == STATUS_EOF)
{
issue_refresh_seek(mpctx, MPSEEK_VERY_EXACT);
}
}
static void check_framedrop(struct MPContext *mpctx, struct vo_chain *vo_c)
{
struct MPOpts *opts = mpctx->opts;
// check for frame-drop:
if (mpctx->video_status == STATUS_PLAYING && !mpctx->paused &&
mpctx->audio_status == STATUS_PLAYING && !ao_untimed(mpctx->ao) &&
vo_c->track && vo_c->track->dec && (opts->frame_dropping & 2))
{
float fps = vo_c->filter->container_fps;
// it's a crappy heuristic; avoid getting upset by incorrect fps
if (fps <= 20 || fps >= 500)
return;
double frame_time = 1.0 / fps;
// try to drop as many frames as we appear to be behind
mp_decoder_wrapper_set_frame_drops(vo_c->track->dec,
MPCLAMP((mpctx->last_av_difference - 0.010) / frame_time, 0, 100));
}
}
/* Modify video timing to match the audio timeline. There are two main
* reasons this is needed. First, video and audio can start from different
* positions at beginning of file or after a seek (MPlayer starts both
* immediately even if they have different pts). Second, the file can have
* audio timestamps that are inconsistent with the duration of the audio
* packets, for example two consecutive timestamp values differing by
* one second but only a packet with enough samples for half a second
* of playback between them.
*/
static void adjust_sync(struct MPContext *mpctx, double v_pts, double frame_time)
{
struct MPOpts *opts = mpctx->opts;
if (mpctx->audio_status != STATUS_PLAYING)
return;
double a_pts = written_audio_pts(mpctx) + opts->audio_delay - mpctx->delay;
double av_delay = a_pts - v_pts;
double change = av_delay * 0.1;
double factor = fabs(av_delay) < 0.3 ? 0.1 : 0.4;
double max_change = opts->default_max_pts_correction >= 0 ?
opts->default_max_pts_correction : frame_time * factor;
if (change < -max_change)
change = -max_change;
else if (change > max_change)
change = max_change;
mpctx->delay += change;
mpctx->total_avsync_change += change;
if (mpctx->display_sync_active)
mpctx->total_avsync_change = 0;
}
// Make the frame at position 0 "known" to the playback logic. This must happen
// only once for each frame, so this function has to be called carefully.
// Generally, if position 0 gets a new frame, this must be called.
static void handle_new_frame(struct MPContext *mpctx)
{
assert(mpctx->num_next_frames >= 1);
double frame_time = 0;
double pts = mpctx->next_frames[0]->pts;
bool is_sparse = mpctx->vo_chain && mpctx->vo_chain->is_sparse;
if (mpctx->video_pts != MP_NOPTS_VALUE) {
frame_time = pts - mpctx->video_pts;
double tolerance = mpctx->demuxer->ts_resets_possible &&
!is_sparse ? 5 : 1e4;
if (frame_time <= 0 || frame_time >= tolerance) {
// Assume a discontinuity.
MP_WARN(mpctx, "Invalid video timestamp: %f -> %f\n",
mpctx->video_pts, pts);
frame_time = 0;
}
}
mpctx->delay -= frame_time;
mpctx->time_frame += frame_time / mpctx->video_speed;
if (mpctx->video_status >= STATUS_PLAYING)
adjust_sync(mpctx, pts, frame_time);
MP_TRACE(mpctx, "frametime=%5.3f\n", frame_time);
}
// Remove the first frame in mpctx->next_frames
static void shift_frames(struct MPContext *mpctx)
{
if (mpctx->num_next_frames < 1)
return;
talloc_free(mpctx->next_frames[0]);
for (int n = 0; n < mpctx->num_next_frames - 1; n++)
mpctx->next_frames[n] = mpctx->next_frames[n + 1];
mpctx->num_next_frames -= 1;
}
static bool use_video_lookahead(struct MPContext *mpctx)
{
return mpctx->video_out &&
!(mpctx->video_out->driver->caps & VO_CAP_NORETAIN) &&
!(mpctx->opts->untimed || mpctx->video_out->driver->untimed) &&
!mpctx->opts->video_latency_hacks;
}
static int get_req_frames(struct MPContext *mpctx, bool eof)
{
// On EOF, drain all frames.
if (eof)
return 1;
if (!use_video_lookahead(mpctx))
return 1;
if (mpctx->vo_chain && mpctx->vo_chain->is_sparse)
return 1;
// Normally require at least 2 frames, so we can compute a frame duration.
int min = 2;
// On the first frame, output a new frame as quickly as possible.
if (mpctx->video_pts == MP_NOPTS_VALUE)
return min;
int req = vo_get_num_req_frames(mpctx->video_out);
return MPCLAMP(req, min, MP_ARRAY_SIZE(mpctx->next_frames) - 1);
}
// Whether it's fine to call add_new_frame() now.
static bool needs_new_frame(struct MPContext *mpctx)
{
return mpctx->num_next_frames < get_req_frames(mpctx, false);
}
// Queue a frame to mpctx->next_frames[]. Call only if needs_new_frame() signals ok.
static void add_new_frame(struct MPContext *mpctx, struct mp_image *frame)
{
assert(mpctx->num_next_frames < MP_ARRAY_SIZE(mpctx->next_frames));
assert(frame);
mpctx->next_frames[mpctx->num_next_frames++] = frame;
if (mpctx->num_next_frames == 1)
handle_new_frame(mpctx);
}
// Enough video filtered already to push one frame to the VO?
// Set eof to true if no new frames are to be expected.
static bool have_new_frame(struct MPContext *mpctx, bool eof)
{
return mpctx->num_next_frames >= get_req_frames(mpctx, eof);
}
// Fill mpctx->next_frames[] with a newly filtered or decoded image.
// logical_eof: is set to true if there is EOF after currently queued frames
// returns VD_* code
static int video_output_image(struct MPContext *mpctx, bool *logical_eof)
{
struct vo_chain *vo_c = mpctx->vo_chain;
bool hrseek = false;
double hrseek_pts = mpctx->hrseek_pts;
double tolerance = mpctx->hrseek_backstep ? 0 : .005;
if (mpctx->video_status == STATUS_SYNCING) {
hrseek = mpctx->hrseek_active;
// playback_pts is normally only set when audio and video have started
// playing normally. If video is in syncing mode, then this must mean
// video was just enabled via track switching - skip to current time.
if (!hrseek && mpctx->playback_pts != MP_NOPTS_VALUE) {
hrseek = true;
hrseek_pts = mpctx->playback_pts;
}
}
if (vo_c->is_coverart) {
*logical_eof = true;
if (vo_has_frame(mpctx->video_out))
return VD_EOF;
hrseek = false;
}
if (have_new_frame(mpctx, false))
return VD_NEW_FRAME;
// Get a new frame if we need one.
int r = VD_PROGRESS;
if (needs_new_frame(mpctx)) {
// Filter a new frame.
struct mp_image *img = NULL;
struct mp_frame frame = mp_pin_out_read(vo_c->filter->f->pins[1]);
if (frame.type == MP_FRAME_NONE) {
r = vo_c->filter->got_output_eof ? VD_EOF : VD_WAIT;
} else if (frame.type == MP_FRAME_EOF) {
r = VD_EOF;
} else if (frame.type == MP_FRAME_VIDEO) {
img = frame.data;
} else {
MP_ERR(mpctx, "unexpected frame type %s\n",
mp_frame_type_str(frame.type));
mp_frame_unref(&frame);
return VD_ERROR;
}
if (img) {
double endpts = get_play_end_pts(mpctx);
if (endpts != MP_NOPTS_VALUE)
endpts *= mpctx->play_dir;
if ((endpts != MP_NOPTS_VALUE && img->pts >= endpts) ||
mpctx->max_frames == 0)
{
mp_pin_out_unread(vo_c->filter->f->pins[1], frame);
img = NULL;
r = VD_EOF;
} else if (hrseek && (img->pts < hrseek_pts - tolerance ||
mpctx->hrseek_lastframe))
{
/* just skip - but save in case it was the last frame */
mp_image_setrefp(&mpctx->saved_frame, img);
} else {
if (hrseek && mpctx->hrseek_backstep) {
if (mpctx->saved_frame) {
add_new_frame(mpctx, mpctx->saved_frame);
mpctx->saved_frame = NULL;
} else {
MP_WARN(mpctx, "Backstep failed.\n");
}
mpctx->hrseek_backstep = false;
}
mp_image_unrefp(&mpctx->saved_frame);
add_new_frame(mpctx, img);
img = NULL;
}
talloc_free(img);
}
}
if (!hrseek)
mp_image_unrefp(&mpctx->saved_frame);
if (r == VD_EOF) {
// If hr-seek went past EOF, use the last frame.
if (mpctx->saved_frame)
add_new_frame(mpctx, mpctx->saved_frame);
mpctx->saved_frame = NULL;
*logical_eof = true;
}
return have_new_frame(mpctx, r <= 0) ? VD_NEW_FRAME : r;
}
static bool check_for_hwdec_fallback(struct MPContext *mpctx)
{
struct vo_chain *vo_c = mpctx->vo_chain;
if (!vo_c->filter->failed_output_conversion || !vo_c->track)
return false;
if (mp_decoder_wrapper_control(vo_c->track->dec,
VDCTRL_FORCE_HWDEC_FALLBACK, NULL) != CONTROL_OK)
return false;
mp_output_chain_reset_harder(vo_c->filter);
return true;
}
/* Update avsync before a new video frame is displayed. Actually, this can be
* called arbitrarily often before the actual display.
* This adjusts the time of the next video frame */
static void update_avsync_before_frame(struct MPContext *mpctx)
{
struct MPOpts *opts = mpctx->opts;
struct vo *vo = mpctx->video_out;
if (mpctx->video_status < STATUS_READY) {
mpctx->time_frame = 0;
} else if (mpctx->display_sync_active || opts->video_sync == VS_NONE) {
// don't touch the timing
} else if (mpctx->audio_status == STATUS_PLAYING &&
mpctx->video_status == STATUS_PLAYING &&
!ao_untimed(mpctx->ao))
{
double buffered_audio = ao_get_delay(mpctx->ao);
double predicted = mpctx->delay / mpctx->video_speed +
mpctx->time_frame;
double difference = buffered_audio - predicted;
MP_STATS(mpctx, "value %f audio-diff", difference);
if (opts->autosync) {
/* Smooth reported playback position from AO by averaging
* it with the value expected based on previus value and
* time elapsed since then. May help smooth video timing
* with audio output that have inaccurate position reporting.
* This is badly implemented; the behavior of the smoothing
* now undesirably depends on how often this code runs
* (mainly depends on video frame rate). */
buffered_audio = predicted + difference / opts->autosync;
}
mpctx->time_frame = buffered_audio - mpctx->delay / mpctx->video_speed;
} else {
/* If we're more than 200 ms behind the right playback
* position, don't try to speed up display of following
* frames to catch up; continue with default speed from
* the current frame instead.
* If untimed is set always output frames immediately
* without sleeping.
*/
if (mpctx->time_frame < -0.2 || opts->untimed || vo->driver->untimed)
mpctx->time_frame = 0;
}
}
// Update the A/V sync difference when a new video frame is being shown.
static void update_av_diff(struct MPContext *mpctx, double offset)
{
struct MPOpts *opts = mpctx->opts;
mpctx->last_av_difference = 0;
if (mpctx->audio_status != STATUS_PLAYING ||
mpctx->video_status != STATUS_PLAYING)
return;
if (mpctx->vo_chain && mpctx->vo_chain->is_sparse)
return;
double a_pos = playing_audio_pts(mpctx);
if (a_pos != MP_NOPTS_VALUE && mpctx->video_pts != MP_NOPTS_VALUE) {
mpctx->last_av_difference = a_pos - mpctx->video_pts
+ opts->audio_delay + offset;
}
if (fabs(mpctx->last_av_difference) > 0.5 && !mpctx->drop_message_shown) {
MP_WARN(mpctx, "%s", av_desync_help_text);
mpctx->drop_message_shown = true;
}
}
double calc_average_frame_duration(struct MPContext *mpctx)
{
double total = 0;
int num = 0;
for (int n = 0; n < mpctx->num_past_frames; n++) {
double dur = mpctx->past_frames[n].approx_duration;
if (dur <= 0)
continue;
total += dur;
num += 1;
}
return num > 0 ? total / num : 0;
}
// Find a speed factor such that the display FPS is an integer multiple of the
// effective video FPS. If this is not possible, try to do it for multiples,
// which still leads to an improved end result.
// Both parameters are durations in seconds.
static double calc_best_speed(double vsync, double frame, int max_factor)
{
double ratio = frame / vsync;
double best_scale = -1;
double best_dev = INFINITY;
for (int factor = 1; factor <= max_factor; factor++) {
double scale = ratio * factor / rint(ratio * factor);
double dev = fabs(scale - 1);
if (dev < best_dev) {
best_scale = scale;
best_dev = dev;
}
}
return best_scale;
}
static double find_best_speed(struct MPContext *mpctx, double vsync)
{
double total = 0;
int num = 0;
for (int n = 0; n < mpctx->num_past_frames; n++) {
double dur = mpctx->past_frames[n].approx_duration;
if (dur <= 0)
continue;
total += calc_best_speed(vsync, dur / mpctx->opts->playback_speed,
mpctx->opts->sync_max_factor);
num++;
}
return num > 0 ? total / num : 1;
}
static bool using_spdif_passthrough(struct MPContext *mpctx)
{
if (mpctx->ao_chain && mpctx->ao_chain->ao) {
int samplerate;
int format;
struct mp_chmap channels;
ao_get_format(mpctx->ao_chain->ao, &samplerate, &format, &channels);
return !af_fmt_is_pcm(format);
}
return false;
}
// Compute the relative audio speed difference by taking A/V dsync into account.
static double compute_audio_drift(struct MPContext *mpctx, double vsync)
{
// Least-squares linear regression, using relative real time for x, and
// audio desync for y. Assume speed didn't change for the frames we're
// looking at for simplicity. This also should actually use the realtime
// (minus paused time) for x, but use vsync scheduling points instead.
if (mpctx->num_past_frames <= 10)
return NAN;
int num = mpctx->num_past_frames - 1;
double sum_x = 0, sum_y = 0, sum_xy = 0, sum_xx = 0;
double x = 0;
for (int n = 0; n < num; n++) {
struct frame_info *frame = &mpctx->past_frames[n + 1];
if (frame->num_vsyncs < 0)
return NAN;
double y = frame->av_diff;
sum_x += x;
sum_y += y;
sum_xy += x * y;
sum_xx += x * x;
x -= frame->num_vsyncs * vsync;
}
return (sum_x * sum_y - num * sum_xy) / (sum_x * sum_x - num * sum_xx);
}
static void adjust_audio_resample_speed(struct MPContext *mpctx, double vsync)
{
struct MPOpts *opts = mpctx->opts;
int mode = opts->video_sync;
if (mode != VS_DISP_RESAMPLE || mpctx->audio_status != STATUS_PLAYING) {
mpctx->speed_factor_a = mpctx->speed_factor_v;
return;
}
// Try to smooth out audio timing drifts. This can happen if either
// video isn't playing at expected speed, or audio is not playing at
// the requested speed. Both are unavoidable.
// The audio desync is made up of 2 parts: 1. drift due to rounding
// errors and imperfect information, and 2. an offset, due to
// unaligned audio/video start, or disruptive events halting audio
// or video for a small time.
// Instead of trying to be clever, just apply an awfully dumb drift
// compensation with a constant factor, which does what we want. In
// theory we could calculate the exact drift compensation needed,
// but it likely would be wrong anyway, and we'd run into the same
// issues again, except with more complex code.
// 1 means drifts to positive, -1 means drifts to negative
double max_drift = vsync / 2;
double av_diff = mpctx->last_av_difference;
int new = mpctx->display_sync_drift_dir;
if (av_diff * -mpctx->display_sync_drift_dir >= 0)
new = 0;
if (fabs(av_diff) > max_drift)
new = av_diff >= 0 ? 1 : -1;
bool change = mpctx->display_sync_drift_dir != new;
if (new || change) {
if (change)
MP_VERBOSE(mpctx, "Change display sync audio drift: %d\n", new);
mpctx->display_sync_drift_dir = new;
double max_correct = opts->sync_max_audio_change / 100;
double audio_factor = 1 + max_correct * -mpctx->display_sync_drift_dir;
if (new == 0) {
// If we're resetting, actually try to be clever and pick a speed
// which compensates the general drift we're getting.
double drift = compute_audio_drift(mpctx, vsync);
if (isnormal(drift)) {
// other = will be multiplied with audio_factor for final speed
double other = mpctx->opts->playback_speed * mpctx->speed_factor_v;
audio_factor = (mpctx->audio_speed - drift) / other;
MP_VERBOSE(mpctx, "Compensation factor: %f\n", audio_factor);
}
}
audio_factor = MPCLAMP(audio_factor, 1 - max_correct, 1 + max_correct);
mpctx->speed_factor_a = audio_factor * mpctx->speed_factor_v;
}
}
// Manipulate frame timing for display sync, or do nothing for normal timing.
static void handle_display_sync_frame(struct MPContext *mpctx,
struct vo_frame *frame)
{
struct MPOpts *opts = mpctx->opts;
struct vo *vo = mpctx->video_out;
int mode = opts->video_sync;
if (!mpctx->display_sync_active) {
mpctx->display_sync_error = 0.0;
mpctx->display_sync_drift_dir = 0;
}
mpctx->display_sync_active = false;
if (!VS_IS_DISP(mode))
return;
bool resample = mode == VS_DISP_RESAMPLE || mode == VS_DISP_RESAMPLE_VDROP ||
mode == VS_DISP_RESAMPLE_NONE;
bool drop = mode == VS_DISP_VDROP || mode == VS_DISP_RESAMPLE ||
mode == VS_DISP_ADROP || mode == VS_DISP_RESAMPLE_VDROP;
drop &= frame->can_drop;
if (resample && using_spdif_passthrough(mpctx))
return;
double vsync = vo_get_vsync_interval(vo) / 1e6;
if (vsync <= 0)
return;
double adjusted_duration = MPMAX(0, mpctx->past_frames[0].approx_duration);
adjusted_duration /= opts->playback_speed;
if (adjusted_duration > 0.5)
return;
mpctx->speed_factor_v = 1.0;
if (mode != VS_DISP_VDROP) {
double best = find_best_speed(mpctx, vsync);
// If it doesn't work, play at normal speed.
if (fabs(best - 1.0) <= opts->sync_max_video_change / 100)
mpctx->speed_factor_v = best;
}
// Determine for how many vsyncs a frame should be displayed. This can be
// e.g. 2 for 30hz on a 60hz display. It can also be 0 if the video
// framerate is higher than the display framerate.
// We use the speed-adjusted (i.e. real) frame duration for this.
double frame_duration = adjusted_duration / mpctx->speed_factor_v;
double ratio = (frame_duration + mpctx->display_sync_error) / vsync;
int num_vsyncs = MPMAX(lrint(ratio), 0);
double prev_error = mpctx->display_sync_error;
mpctx->display_sync_error += frame_duration - num_vsyncs * vsync;
MP_TRACE(mpctx, "s=%f vsyncs=%d dur=%f ratio=%f err=%.20f (%f/%f)\n",
mpctx->speed_factor_v, num_vsyncs, adjusted_duration, ratio,
mpctx->display_sync_error, mpctx->display_sync_error / vsync,
mpctx->display_sync_error / frame_duration);
double av_diff = mpctx->last_av_difference;
MP_STATS(mpctx, "value %f avdiff", av_diff);
// Intended number of additional display frames to drop (<0) or repeat (>0)
int drop_repeat = 0;
// If we are too far ahead/behind, attempt to drop/repeat frames.
// Tolerate some desync to avoid frame dropping due to jitter.
if (drop && fabs(av_diff) >= 0.020 && fabs(av_diff) / vsync >= 1)
drop_repeat = -av_diff / vsync; // round towards 0
// We can only drop all frames at most. We can repeat much more frames,
// but we still limit it to 10 times the original frames to avoid that
// corner cases or exceptional situations cause too much havoc.
drop_repeat = MPCLAMP(drop_repeat, -num_vsyncs, num_vsyncs * 10);
num_vsyncs += drop_repeat;
// Always show the first frame.
if (mpctx->num_past_frames <= 1 && num_vsyncs < 1)
num_vsyncs = 1;
// Estimate the video position, so we can calculate a good A/V difference
// value below. This is used to estimate A/V drift.
double time_left = vo_get_delay(vo);
// We also know that the timing is (necessarily) off, because we have to
// align frame timings on the vsync boundaries. This is unavoidable, and
// for the sake of the A/V sync calculations we pretend it's perfect.
time_left += prev_error;
// Likewise, we know sync is off, but is going to be compensated.
time_left += drop_repeat * vsync;
// If syncing took too long, disregard timing of the first frame.
if (mpctx->num_past_frames == 2 && time_left < 0) {
vo_discard_timing_info(vo);
time_left = 0;
}
if (drop_repeat) {
mpctx->mistimed_frames_total += 1;
MP_STATS(mpctx, "mistimed");
}
mpctx->total_avsync_change = 0;
update_av_diff(mpctx, time_left * opts->playback_speed);
mpctx->past_frames[0].num_vsyncs = num_vsyncs;
mpctx->past_frames[0].av_diff = mpctx->last_av_difference;
if (resample || mode == VS_DISP_ADROP) {
adjust_audio_resample_speed(mpctx, vsync);
} else {
mpctx->speed_factor_a = 1.0;
}
// A bad guess, only needed when reverting to audio sync.
mpctx->time_frame = time_left;
frame->vsync_interval = vsync;
frame->vsync_offset = -prev_error;
frame->ideal_frame_duration = frame_duration;
frame->num_vsyncs = num_vsyncs;
frame->display_synced = true;
mpctx->display_sync_active = true;
update_playback_speed(mpctx);
MP_STATS(mpctx, "value %f aspeed", mpctx->speed_factor_a - 1);
MP_STATS(mpctx, "value %f vspeed", mpctx->speed_factor_v - 1);
}
static void schedule_frame(struct MPContext *mpctx, struct vo_frame *frame)
{
handle_display_sync_frame(mpctx, frame);
if (mpctx->num_past_frames > 1 &&
((mpctx->past_frames[1].num_vsyncs >= 0) != mpctx->display_sync_active))
{
MP_VERBOSE(mpctx, "Video sync mode %s.\n",
mpctx->display_sync_active ? "enabled" : "disabled");
}
if (!mpctx->display_sync_active) {
mpctx->speed_factor_a = 1.0;
mpctx->speed_factor_v = 1.0;
update_playback_speed(mpctx);
update_av_diff(mpctx, mpctx->time_frame > 0 ?
mpctx->time_frame * mpctx->video_speed : 0);
}
}
// Determine the mpctx->past_frames[0] frame duration.
static void calculate_frame_duration(struct MPContext *mpctx)
{
struct vo_chain *vo_c = mpctx->vo_chain;
assert(mpctx->num_past_frames >= 1 && mpctx->num_next_frames >= 1);
double demux_duration = vo_c->filter->container_fps > 0
? 1.0 / vo_c->filter->container_fps : -1;
double duration = demux_duration;
if (mpctx->num_next_frames >= 2) {
double pts0 = mpctx->next_frames[0]->pts;
double pts1 = mpctx->next_frames[1]->pts;
if (pts0 != MP_NOPTS_VALUE && pts1 != MP_NOPTS_VALUE && pts1 >= pts0)
duration = pts1 - pts0;
}
// The following code tries to compensate for rounded Matroska timestamps
// by "unrounding" frame durations, or if not possible, approximating them.
// These formats usually round on 1ms. Some muxers do this incorrectly,
// and might go off by 1ms more, and compensate for it later by an equal
// rounding error into the opposite direction.
double tolerance = 0.001 * 3 + 0.0001;
double total = 0;
int num_dur = 0;
for (int n = 1; n < mpctx->num_past_frames; n++) {
// Eliminate likely outliers using a really dumb heuristic.
double dur = mpctx->past_frames[n].duration;
if (dur <= 0 || fabs(dur - duration) >= tolerance)
break;
total += dur;
num_dur += 1;
}
double approx_duration = num_dur > 0 ? total / num_dur : duration;
// Try if the demuxer frame rate fits - if so, just take it.
if (demux_duration > 0) {
// Note that even if each timestamp is within rounding tolerance, it
// could literally not add up (e.g. if demuxer FPS is rounded itself).
if (fabs(duration - demux_duration) < tolerance &&
fabs(total - demux_duration * num_dur) < tolerance &&
(num_dur >= 16 || num_dur >= mpctx->num_past_frames - 4))
{
approx_duration = demux_duration;
}
}
mpctx->past_frames[0].duration = duration;
mpctx->past_frames[0].approx_duration = approx_duration;
MP_STATS(mpctx, "value %f frame-duration", MPMAX(0, duration));
MP_STATS(mpctx, "value %f frame-duration-approx", MPMAX(0, approx_duration));
}
void write_video(struct MPContext *mpctx)
{
struct MPOpts *opts = mpctx->opts;
if (!mpctx->vo_chain)
return;
struct track *track = mpctx->vo_chain->track;
struct vo_chain *vo_c = mpctx->vo_chain;
struct vo *vo = vo_c->vo;
if (vo_c->filter->reconfig_happened) {
mp_notify(mpctx, MPV_EVENT_VIDEO_RECONFIG, NULL);
vo_c->filter->reconfig_happened = false;
}
// Actual playback starts when both audio and video are ready.
if (mpctx->video_status == STATUS_READY)
return;
if (mpctx->paused && mpctx->video_status >= STATUS_READY)
return;
bool logical_eof = false;
int r = video_output_image(mpctx, &logical_eof);
MP_TRACE(mpctx, "video_output_image: r=%d/eof=%d/st=%s\n", r, logical_eof,
mp_status_str(mpctx->video_status));
if (r < 0)
goto error;
if (r == VD_WAIT) {
// Heuristic to detect underruns.
if (mpctx->video_status == STATUS_PLAYING && !vo_still_displaying(vo) &&
!vo_c->underrun_signaled)
{
vo_c->underrun = true;
vo_c->underrun_signaled = true;
}
// Demuxer will wake us up for more packets to decode.
return;
}
if (r == VD_EOF) {
if (check_for_hwdec_fallback(mpctx))
return;
if (vo_c->filter->failed_output_conversion)
goto error;
mpctx->delay = 0;
mpctx->last_av_difference = 0;
if (mpctx->video_status <= STATUS_PLAYING) {
mpctx->video_status = STATUS_DRAINING;
get_relative_time(mpctx);
if (vo_c->is_sparse && !mpctx->ao_chain) {
MP_VERBOSE(mpctx, "assuming this is an image\n");
mpctx->time_frame += opts->image_display_duration;
} else if (mpctx->last_frame_duration > 0) {
MP_VERBOSE(mpctx, "using demuxer frame duration for last frame\n");
mpctx->time_frame += mpctx->last_frame_duration;
} else {
mpctx->time_frame = 0;
}
// Encode mode can't honor this; it'll only delay finishing.
if (mpctx->encode_lavc_ctx)
mpctx->time_frame = 0;
}
// Wait for the VO to signal actual EOF, then exit if the frame timer
// has expired.
bool has_frame = vo_has_frame(vo); // maybe not configured
if (mpctx->video_status == STATUS_DRAINING &&
(vo_is_ready_for_frame(vo, -1) || !has_frame))
{
mpctx->time_frame -= get_relative_time(mpctx);
mp_set_timeout(mpctx, mpctx->time_frame);
if (mpctx->time_frame <= 0 || !has_frame) {
MP_VERBOSE(mpctx, "video EOF reached\n");
mpctx->video_status = STATUS_EOF;
encode_lavc_stream_eof(mpctx->encode_lavc_ctx, STREAM_VIDEO);
}
}
MP_DBG(mpctx, "video EOF (status=%d)\n", mpctx->video_status);
return;
}
if (mpctx->video_status > STATUS_PLAYING)
mpctx->video_status = STATUS_PLAYING;
if (r != VD_NEW_FRAME) {
mp_wakeup_core(mpctx); // Decode more in next iteration.
return;
}
if (logical_eof && !mpctx->num_past_frames && mpctx->num_next_frames == 1 &&
use_video_lookahead(mpctx) && !vo_c->is_sparse)
{
// Too much danger to accidentally mark video as sparse when e.g.
// seeking exactly to the last frame, so as a heuristic, do this only
// if it looks like the "first" video frame (unreliable, but often
// works out well). Helps with seeking with single-image video tracks,
// as well as detecting whether as video track is really an image.
if (mpctx->next_frames[0]->pts == 0) {
MP_VERBOSE(mpctx, "assuming single-image video stream\n");
vo_c->is_sparse = true;
}
}
// Filter output is different from VO input?
struct mp_image_params p = mpctx->next_frames[0]->params;
if (!vo->params || !mp_image_params_equal(&p, vo->params)) {
// Changing config deletes the current frame; wait until it's finished.
if (vo_still_displaying(vo)) {
vo_request_wakeup_on_done(vo);
return;
}
const struct vo_driver *info = mpctx->video_out->driver;
char extra[20] = {0};
if (p.p_w != p.p_h) {
int d_w, d_h;
mp_image_params_get_dsize(&p, &d_w, &d_h);
snprintf(extra, sizeof(extra), " => %dx%d", d_w, d_h);
}
char sfmt[20] = {0};
if (p.hw_subfmt)
snprintf(sfmt, sizeof(sfmt), "[%s]", mp_imgfmt_to_name(p.hw_subfmt));
MP_INFO(mpctx, "VO: [%s] %dx%d%s %s%s\n",
info->name, p.w, p.h, extra, mp_imgfmt_to_name(p.imgfmt), sfmt);
MP_VERBOSE(mpctx, "VO: Description: %s\n", info->description);
int vo_r = vo_reconfig2(vo, mpctx->next_frames[0]);
if (vo_r < 0) {
mpctx->error_playing = MPV_ERROR_VO_INIT_FAILED;
goto error;
}
mp_notify(mpctx, MPV_EVENT_VIDEO_RECONFIG, NULL);
}
mpctx->time_frame -= get_relative_time(mpctx);
update_avsync_before_frame(mpctx);
// Enforce timing subtitles to video frames.
osd_set_force_video_pts(mpctx->osd, MP_NOPTS_VALUE);
if (!update_subtitles(mpctx, mpctx->next_frames[0]->pts)) {
MP_VERBOSE(mpctx, "Video frame delayed due to waiting on subtitles.\n");
return;
}
double time_frame = MPMAX(mpctx->time_frame, -1);
int64_t pts = mp_time_us() + (int64_t)(time_frame * 1e6);
// wait until VO wakes us up to get more frames
// (NB: in theory, the 1st frame after display sync mode change uses the
// wrong waiting mode)
if (!vo_is_ready_for_frame(vo, mpctx->display_sync_active ? -1 : pts))
return;
assert(mpctx->num_next_frames >= 1);
if (mpctx->num_past_frames >= MAX_NUM_VO_PTS)
mpctx->num_past_frames--;
MP_TARRAY_INSERT_AT(mpctx, mpctx->past_frames, mpctx->num_past_frames, 0,
(struct frame_info){0});
mpctx->past_frames[0] = (struct frame_info){
.pts = mpctx->next_frames[0]->pts,
.num_vsyncs = -1,
};
calculate_frame_duration(mpctx);
int req = vo_get_num_req_frames(mpctx->video_out);
assert(req >= 1 && req <= VO_MAX_REQ_FRAMES);
struct vo_frame dummy = {
.pts = pts,
.duration = -1,
.still = mpctx->step_frames > 0,
.can_drop = opts->frame_dropping & 1,
.num_frames = MPMIN(mpctx->num_next_frames, req),
.num_vsyncs = 1,
};
for (int n = 0; n < dummy.num_frames; n++)
dummy.frames[n] = mpctx->next_frames[n];
struct vo_frame *frame = vo_frame_ref(&dummy);
double diff = mpctx->past_frames[0].approx_duration;
if (opts->untimed || vo->driver->untimed)
diff = -1; // disable frame dropping and aspects of frame timing
if (diff >= 0) {
// expected A/V sync correction is ignored
diff /= mpctx->video_speed;
if (mpctx->time_frame < 0)
diff += mpctx->time_frame;
frame->duration = MPCLAMP(diff, 0, 10) * 1e6;
}
mpctx->video_pts = mpctx->next_frames[0]->pts;
mpctx->last_frame_duration =
mpctx->next_frames[0]->pkt_duration / mpctx->video_speed;
shift_frames(mpctx);
schedule_frame(mpctx, frame);
mpctx->osd_force_update = true;
update_osd_msg(mpctx);
vo_queue_frame(vo, frame);
check_framedrop(mpctx, vo_c);
// The frames were shifted down; "initialize" the new first entry.
if (mpctx->num_next_frames >= 1)
handle_new_frame(mpctx);
mpctx->shown_vframes++;
if (mpctx->video_status < STATUS_PLAYING) {
mpctx->video_status = STATUS_READY;
// After a seek, make sure to wait until the first frame is visible.
if (!opts->video_latency_hacks) {
vo_wait_frame(vo);
MP_VERBOSE(mpctx, "first video frame after restart shown\n");
}
}
mp_notify(mpctx, MPV_EVENT_TICK, NULL);
// hr-seek past EOF -> returns last frame, but terminates playback. The
// early EOF is needed to trigger the exit before the next seek is executed.
// Always using early EOF breaks other cases, like images.
if (logical_eof && !mpctx->num_next_frames && mpctx->ao_chain)
mpctx->video_status = STATUS_EOF;
if (mpctx->video_status != STATUS_EOF) {
if (mpctx->step_frames > 0) {
mpctx->step_frames--;
if (!mpctx->step_frames)
set_pause_state(mpctx, true);
}
if (mpctx->max_frames == 0 && !mpctx->stop_play)
mpctx->stop_play = AT_END_OF_FILE;
if (mpctx->max_frames > 0)
mpctx->max_frames--;
}
vo_c->underrun_signaled = false;
if (mpctx->video_status == STATUS_EOF || mpctx->stop_play)
mp_wakeup_core(mpctx);
return;
error:
MP_FATAL(mpctx, "Could not initialize video chain.\n");
uninit_video_chain(mpctx);
error_on_track(mpctx, track);
handle_force_window(mpctx, true);
mp_wakeup_core(mpctx);
}
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