mpv/demux/demux.c

/*
 * This file is part of MPlayer.
 *
 * MPlayer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * MPlayer 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <pthread.h>

#include <math.h>

#include <sys/types.h>
#include <sys/stat.h>

#include "config.h"
#include "options/options.h"
#include "talloc.h"
#include "common/msg.h"
#include "common/global.h"

#include "stream/stream.h"
#include "demux.h"
#include "stheader.h"
#include "mf.h"

#include "audio/format.h"

// Demuxer list
extern const struct demuxer_desc demuxer_desc_edl;
extern const struct demuxer_desc demuxer_desc_cue;
extern const demuxer_desc_t demuxer_desc_rawaudio;
extern const demuxer_desc_t demuxer_desc_rawvideo;
extern const demuxer_desc_t demuxer_desc_tv;
extern const demuxer_desc_t demuxer_desc_mf;
extern const demuxer_desc_t demuxer_desc_matroska;
extern const demuxer_desc_t demuxer_desc_lavf;
extern const demuxer_desc_t demuxer_desc_libass;
extern const demuxer_desc_t demuxer_desc_subreader;
extern const demuxer_desc_t demuxer_desc_playlist;
extern const demuxer_desc_t demuxer_desc_disc;

/* Please do not add any new demuxers here. If you want to implement a new
 * demuxer, add it to libavformat, except for wrappers around external
 * libraries and demuxers requiring binary support. */

const demuxer_desc_t *const demuxer_list[] = {
    &demuxer_desc_disc,
    &demuxer_desc_edl,
    &demuxer_desc_cue,
    &demuxer_desc_rawaudio,
    &demuxer_desc_rawvideo,
#if HAVE_TV
    &demuxer_desc_tv,
#endif
#if HAVE_LIBASS
    &demuxer_desc_libass,
#endif
    &demuxer_desc_matroska,
    &demuxer_desc_lavf,
    &demuxer_desc_mf,
    &demuxer_desc_playlist,
    // Pretty aggressive, so should be last.
    &demuxer_desc_subreader,
    NULL
};

struct demux_internal {
    struct mp_log *log;

    // The demuxer runs potentially in another thread, so we keep two demuxer
    // structs; the real demuxer can access the shadow struct only.
    // Since demuxer and user threads both don't use locks, a third demuxer
    // struct d_buffer is used to copy data between them in a synchronized way.
    struct demuxer *d_thread;   // accessed by demuxer impl. (producer)
    struct demuxer *d_user;     // accessed by player (consumer)
    struct demuxer *d_buffer;   // protected by lock; used to sync d_user/thread

    // The lock protects the packet queues (struct demux_stream), d_buffer,
    // and some minor fields like thread_paused.
    pthread_mutex_t lock;
    pthread_cond_t wakeup;
    pthread_t thread;

    // -- All the following fields are protected by lock.

    bool thread_paused;
    int thread_request_pause;   // counter, if >0, make demuxer thread pause
    bool thread_terminate;
    bool threading;
    void (*wakeup_cb)(void *ctx);
    void *wakeup_cb_ctx;

    bool warned_queue_overflow;
    bool last_eof;              // last actual global EOF status
    bool eof;                   // whether we're in EOF state (reset for retry)
    bool autoselect;
    int min_packs;
    int min_bytes;

    // Cached state.
    double time_length;
    struct mp_tags *stream_metadata;
    int64_t stream_size;
    int64_t stream_cache_size;
    int64_t stream_cache_fill;
    int stream_cache_idle;
};

struct demux_stream {
    struct demux_internal *in;
    enum stream_type type;
    // all fields are protected by in->lock
    bool selected;          // user wants packets from this stream
    bool active;            // try to keep at least 1 packet queued
    bool eof;               // end of demuxed stream? (true if all buffer empty)
    size_t packs;           // number of packets in buffer
    size_t bytes;           // total bytes of packets in buffer
    struct demux_packet *head;
    struct demux_packet *tail;
};

static void demuxer_sort_chapters(demuxer_t *demuxer);
static void *demux_thread(void *pctx);
static void update_cache(struct demux_internal *in);

// called locked
static void ds_flush(struct demux_stream *ds)
{
    demux_packet_t *dp = ds->head;
    while (dp) {
        demux_packet_t *dn = dp->next;
        free_demux_packet(dp);
        dp = dn;
    }
    ds->head = ds->tail = NULL;
    ds->packs = 0;
    ds->bytes = 0;
    ds->eof = false;
    ds->active = false;
}

struct sh_stream *new_sh_stream(demuxer_t *demuxer, enum stream_type type)
{
    assert(demuxer == demuxer->in->d_thread);

    if (demuxer->num_streams > MAX_SH_STREAMS) {
        MP_WARN(demuxer, "Too many streams.\n");
        return NULL;
    }

    int demuxer_id = 0;
    for (int n = 0; n < demuxer->num_streams; n++) {
        if (demuxer->streams[n]->type == type)
            demuxer_id++;
    }

    struct sh_stream *sh = talloc_ptrtype(demuxer, sh);
    *sh = (struct sh_stream) {
        .type = type,
        .index = demuxer->num_streams,
        .demuxer_id = demuxer_id, // may be overwritten by demuxer
        .ds = talloc(sh, struct demux_stream),
    };
    *sh->ds = (struct demux_stream) {
        .in = demuxer->in,
        .type = sh->type,
        .selected = demuxer->in->autoselect,
    };
    MP_TARRAY_APPEND(demuxer, demuxer->streams, demuxer->num_streams, sh);
    switch (sh->type) {
    case STREAM_VIDEO: sh->video = talloc_zero(demuxer, struct sh_video); break;
    case STREAM_AUDIO: sh->audio = talloc_zero(demuxer, struct sh_audio); break;
    case STREAM_SUB:   sh->sub = talloc_zero(demuxer, struct sh_sub); break;
    }

    return sh;
}

void free_demuxer(demuxer_t *demuxer)
{
    if (!demuxer)
        return;
    struct demux_internal *in = demuxer->in;
    assert(demuxer == in->d_user);

    demux_stop_thread(demuxer);

    if (demuxer->desc->close)
        demuxer->desc->close(in->d_thread);
    for (int n = 0; n < demuxer->num_streams; n++)
        ds_flush(demuxer->streams[n]->ds);
    pthread_mutex_destroy(&in->lock);
    pthread_cond_destroy(&in->wakeup);
    talloc_free(demuxer);
}

// Start the demuxer thread, which reads ahead packets on its own.
void demux_start_thread(struct demuxer *demuxer)
{
    struct demux_internal *in = demuxer->in;
    assert(demuxer == in->d_user);

    if (!in->threading) {
        in->threading = true;
        if (pthread_create(&in->thread, NULL, demux_thread, in))
            in->threading = false;
    }
}

void demux_stop_thread(struct demuxer *demuxer)
{
    struct demux_internal *in = demuxer->in;
    assert(demuxer == in->d_user);

    if (in->threading) {
        pthread_mutex_lock(&in->lock);
        in->thread_terminate = true;
        pthread_cond_signal(&in->wakeup);
        pthread_mutex_unlock(&in->lock);
        pthread_join(in->thread, NULL);
        in->threading = false;
        in->thread_terminate = false;
    }
}

// The demuxer thread will call cb(ctx) if there's a new packet, or EOF is reached.
void demux_set_wakeup_cb(struct demuxer *demuxer, void (*cb)(void *ctx), void *ctx)
{
    struct demux_internal *in = demuxer->in;
    pthread_mutex_lock(&in->lock);
    in->wakeup_cb = cb;
    in->wakeup_cb_ctx = ctx;
    pthread_mutex_unlock(&in->lock);
}

const char *stream_type_name(enum stream_type type)
{
    switch (type) {
    case STREAM_VIDEO:  return "video";
    case STREAM_AUDIO:  return "audio";
    case STREAM_SUB:    return "sub";
    default:            return "unknown";
    }
}

// Returns the same value as demuxer->fill_buffer: 1 ok, 0 EOF/not selected.
int demux_add_packet(struct sh_stream *stream, demux_packet_t *dp)
{
    struct demux_stream *ds = stream ? stream->ds : NULL;
    if (!dp || !ds) {
        talloc_free(dp);
        return 0;
    }
    struct demux_internal *in = ds->in;
    pthread_mutex_lock(&in->lock);
    if (!ds->selected) {
        pthread_mutex_unlock(&in->lock);
        talloc_free(dp);
        return 0;
    }

    dp->stream = stream->index;
    dp->next = NULL;

    ds->packs++;
    ds->bytes += dp->len;
    if (ds->tail) {
        // next packet in stream
        ds->tail->next = dp;
        ds->tail = dp;
    } else {
        // first packet in stream
        ds->head = ds->tail = dp;
    }
    // obviously not true anymore
    ds->eof = false;
    in->last_eof = in->eof = false;

    // For video, PTS determination is not trivial, but for other media types
    // distinguishing PTS and DTS is not useful.
    if (stream->type != STREAM_VIDEO && dp->pts == MP_NOPTS_VALUE)
        dp->pts = dp->dts;

    MP_DBG(in, "append packet to %s: size=%d pts=%f dts=%f pos=%"PRIi64" "
           "[num=%zd size=%zd]\n", stream_type_name(stream->type),
           dp->len, dp->pts, dp->dts, dp->pos, ds->packs, ds->bytes);

    if (ds->in->wakeup_cb)
        ds->in->wakeup_cb(ds->in->wakeup_cb_ctx);
    pthread_cond_signal(&in->wakeup);
    pthread_mutex_unlock(&in->lock);
    return 1;
}

// Returns true if there was "progress" (lock was released temporarily).
static bool read_packet(struct demux_internal *in)
{
    in->eof = false;

    // Check if we need to read a new packet. We do this if all queues are below
    // the minimum, or if a stream explicitly needs new packets. Also includes
    // safe-guards against packet queue overflow.
    bool active = false, read_more = false;
    size_t packs = 0, bytes = 0;
    for (int n = 0; n < in->d_buffer->num_streams; n++) {
        struct demux_stream *ds = in->d_buffer->streams[n]->ds;
        active |= ds->selected;
        read_more |= ds->active && !ds->head;
        packs += ds->packs;
        bytes += ds->bytes;
    }
    MP_DBG(in, "packets=%zd, bytes=%zd, active=%d, more=%d\n",
           packs, bytes, active, read_more);
    if (packs >= MAX_PACKS || bytes >= MAX_PACK_BYTES) {
        if (!in->warned_queue_overflow) {
            in->warned_queue_overflow = true;
            MP_ERR(in, "Too many packets in the demuxer packet queues:\n");
            for (int n = 0; n < in->d_buffer->num_streams; n++) {
                struct demux_stream *ds = in->d_buffer->streams[n]->ds;
                if (ds->selected) {
                    MP_ERR(in, "  %s/%d: %zd packets, %zd bytes\n",
                           stream_type_name(ds->type), n, ds->packs, ds->bytes);
                }
            }
        }
        for (int n = 0; n < in->d_buffer->num_streams; n++) {
            struct demux_stream *ds = in->d_buffer->streams[n]->ds;
            ds->eof |= !ds->head;
        }
        pthread_cond_signal(&in->wakeup);
        return false;
    }
    if (packs < in->min_packs && bytes < in->min_bytes)
        read_more |= active;

    if (!read_more)
        return false;

    // Actually read a packet. Drop the lock while doing so, because waiting
    // for disk or network I/O can take time.
    pthread_mutex_unlock(&in->lock);
    struct demuxer *demux = in->d_thread;
    bool eof = !demux->desc->fill_buffer || demux->desc->fill_buffer(demux) <= 0;
    pthread_mutex_lock(&in->lock);

    update_cache(in);

    if (eof) {
        for (int n = 0; n < in->d_buffer->num_streams; n++) {
            struct demux_stream *ds = in->d_buffer->streams[n]->ds;
            ds->eof = true;
            ds->active = false;
        }
        // If we had EOF previously, then donn't wakeup (avoids wakeup loop)
        if (!in->last_eof) {
            if (in->wakeup_cb)
                in->wakeup_cb(in->wakeup_cb_ctx);
            pthread_cond_signal(&in->wakeup);
            MP_VERBOSE(in, "EOF reached.\n");
        }
    }
    in->eof = in->last_eof = eof;
    return true;
}

// must be called locked; may temporarily unlock
static void ds_get_packets(struct demux_stream *ds)
{
    const char *t = stream_type_name(ds->type);
    struct demux_internal *in = ds->in;
    MP_DBG(in, "reading packet for %s\n", t);
    in->eof = false; // force retry
    ds->eof = false;
    while (ds->selected && !ds->head && !ds->eof) {
        ds->active = true;
        // Note: the following code marks EOF if it can't continue
        if (in->threading) {
            MP_VERBOSE(in, "waiting for demux thread (%s)\n", t);
            pthread_cond_signal(&in->wakeup);
            pthread_cond_wait(&in->wakeup, &in->lock);
        } else {
            read_packet(in);
        }
    }
}

static void *demux_thread(void *pctx)
{
    struct demux_internal *in = pctx;
    pthread_mutex_lock(&in->lock);
    while (!in->thread_terminate) {
        in->thread_paused = in->thread_request_pause > 0;
        if (in->thread_paused) {
            pthread_cond_signal(&in->wakeup);
            pthread_cond_wait(&in->wakeup, &in->lock);
            continue;
        }
        if (!in->eof) {
            if (read_packet(in))
                continue; // read_packet unlocked, so recheck conditions
        }
        update_cache(in);
        pthread_cond_signal(&in->wakeup);
        pthread_cond_wait(&in->wakeup, &in->lock);
    }
    pthread_mutex_unlock(&in->lock);
    return NULL;
}

static struct demux_packet *dequeue_packet(struct demux_stream *ds)
{
    if (!ds->head)
        return NULL;
    struct demux_packet *pkt = ds->head;
    ds->head = pkt->next;
    pkt->next = NULL;
    if (!ds->head)
        ds->tail = NULL;
    ds->bytes -= pkt->len;
    ds->packs--;

    // This implies this function is actually called from "the" user thread.
    if (pkt && pkt->pos >= 0)
        ds->in->d_user->filepos = pkt->pos;

    return pkt;
}

// Read a packet from the given stream. The returned packet belongs to the
// caller, who has to free it with talloc_free(). Might block. Returns NULL
// on EOF.
struct demux_packet *demux_read_packet(struct sh_stream *sh)
{
    struct demux_stream *ds = sh ? sh->ds : NULL;
    struct demux_packet *pkt = NULL;
    if (ds) {
        pthread_mutex_lock(&ds->in->lock);
        ds_get_packets(ds);
        pkt = dequeue_packet(ds);
        pthread_cond_signal(&ds->in->wakeup); // possibly read more
        pthread_mutex_unlock(&ds->in->lock);
    }
    return pkt;
}

// Poll the demuxer queue, and if there's a packet, return it. Otherwise, just
// make the demuxer thread read packets for this stream, and if there's at
// least one packet, call the wakeup callback.
// Unlike demux_read_packet(), this always enables readahead (which means you
// must not use it on interleaved subtitle streams).
// Returns:
//   < 0: EOF was reached, *out_pkt=NULL
//  == 0: no new packet yet, but maybe later, *out_pkt=NULL
//   > 0: new packet read, *out_pkt is set
int demux_read_packet_async(struct sh_stream *sh, struct demux_packet **out_pkt)
{
    struct demux_stream *ds = sh ? sh->ds : NULL;
    int r = -1;
    *out_pkt = NULL;
    if (ds) {
        if (ds->in->threading) {
            pthread_mutex_lock(&ds->in->lock);
            *out_pkt = dequeue_packet(ds);
            r = *out_pkt ? 1 : (ds->eof ? -1 : 0);
            ds->active = ds->selected; // enable readahead
            ds->in->eof = false; // force retry
            pthread_cond_signal(&ds->in->wakeup); // possibly read more
            pthread_mutex_unlock(&ds->in->lock);
        } else {
            *out_pkt = demux_read_packet(sh);
            r = *out_pkt ? 1 : -1;
        }
    }
    return r;
}

// Return the pts of the next packet that demux_read_packet() would return.
// Might block. Sometimes used to force a packet read, without removing any
// packets from the queue.
double demux_get_next_pts(struct sh_stream *sh)
{
    double res = MP_NOPTS_VALUE;
    if (sh) {
        pthread_mutex_lock(&sh->ds->in->lock);
        ds_get_packets(sh->ds);
        if (sh->ds->head)
            res = sh->ds->head->pts;
        pthread_mutex_unlock(&sh->ds->in->lock);
    }
    return res;
}

// Return whether a packet is queued. Never blocks, never forces any reads.
bool demux_has_packet(struct sh_stream *sh)
{
    bool has_packet = false;
    if (sh) {
        pthread_mutex_lock(&sh->ds->in->lock);
        has_packet = sh->ds->head;
        pthread_mutex_unlock(&sh->ds->in->lock);
    }
    return has_packet;
}

// Return whether EOF was returned with an earlier packet read.
bool demux_stream_eof(struct sh_stream *sh)
{
    bool eof = false;
    if (sh) {
        pthread_mutex_lock(&sh->ds->in->lock);
        eof = sh->ds->eof && !sh->ds->head;
        pthread_mutex_unlock(&sh->ds->in->lock);
    }
    return eof;
}

// Read and return any packet we find.
struct demux_packet *demux_read_any_packet(struct demuxer *demuxer)
{
    assert(!demuxer->in->threading); // doesn't work with threading
    for (int retry = 0; retry < 2; retry++) {
        for (int n = 0; n < demuxer->num_streams; n++) {
            struct sh_stream *sh = demuxer->streams[n];
            sh->ds->active = sh->ds->selected; // force read_packet() to read
            struct demux_packet *pkt = dequeue_packet(sh->ds);
            if (pkt)
                return pkt;
        }
        // retry after calling this
        pthread_mutex_lock(&demuxer->in->lock);
        read_packet(demuxer->in);
        pthread_mutex_unlock(&demuxer->in->lock);
    }
    return NULL;
}

// ====================================================================

void demuxer_help(struct mp_log *log)
{
    int i;

    mp_info(log, "Available demuxers:\n");
    mp_info(log, " demuxer:   info:\n");
    for (i = 0; demuxer_list[i]; i++) {
        mp_info(log, "%10s  %s\n",
                demuxer_list[i]->name, demuxer_list[i]->desc);
    }
}

static const char *d_level(enum demux_check level)
{
    switch (level) {
    case DEMUX_CHECK_FORCE:  return "force";
    case DEMUX_CHECK_UNSAFE: return "unsafe";
    case DEMUX_CHECK_REQUEST:return "request";
    case DEMUX_CHECK_NORMAL: return "normal";
    }
    abort();
}

static int decode_float(char *str, float *out)
{
    char *rest;
    float dec_val;

    dec_val = strtod(str, &rest);
    if (!rest || (rest == str) || !isfinite(dec_val))
        return -1;

    *out = dec_val;
    return 0;
}

static int decode_gain(demuxer_t *demuxer, const char *tag, float *out)
{
    char *tag_val = NULL;
    float dec_val;

    tag_val = mp_tags_get_str(demuxer->metadata, tag);
    if (!tag_val) {
        mp_msg(demuxer->log, MSGL_V, "Replaygain tags not found\n");
        return -1;
    }

    if (decode_float(tag_val, &dec_val)) {
        mp_msg(demuxer->log, MSGL_ERR, "Invalid replaygain value\n");
        return -1;
    }

    *out = dec_val;
    return 0;
}

static int decode_peak(demuxer_t *demuxer, const char *tag, float *out)
{
    char *tag_val = NULL;
    float dec_val;

    *out = 1.0;

    tag_val = mp_tags_get_str(demuxer->metadata, tag);
    if (!tag_val)
        return 0;

    if (decode_float(tag_val, &dec_val))
        return 0;

    if (dec_val == 0.0)
        return 0;

    *out = dec_val;
    return 0;
}

static void demux_export_replaygain(demuxer_t *demuxer)
{
    float tg, tp, ag, ap;

    if (!decode_gain(demuxer, "REPLAYGAIN_TRACK_GAIN", &tg) &&
        !decode_peak(demuxer, "REPLAYGAIN_TRACK_PEAK", &tp) &&
        !decode_gain(demuxer, "REPLAYGAIN_ALBUM_GAIN", &ag) &&
        !decode_peak(demuxer, "REPLAYGAIN_ALBUM_PEAK", &ap))
    {
        struct replaygain_data *rgain = talloc_ptrtype(demuxer, rgain);

        rgain->track_gain = tg;
        rgain->track_peak = tp;
        rgain->album_gain = ag;
        rgain->album_peak = ap;

        for (int n = 0; n < demuxer->num_streams; n++) {
            struct sh_stream *sh = demuxer->streams[n];
            if (sh->audio && !sh->audio->replaygain_data)
                sh->audio->replaygain_data = rgain;
        }
    }
}

// Copy all fields from src to dst, depending on event flags.
static void demux_copy(struct demuxer *dst, struct demuxer *src)
{
    if (src->events & DEMUX_EVENT_INIT) {
        // Note that we do as shallow copies as possible. We expect the date
        // that is not-copied (only referenced) to be immutable.
        // This implies e.g. that no chapters are added after initialization.
        dst->chapters = src->chapters;
        dst->num_chapters = src->num_chapters;
        dst->editions = src->editions;
        dst->num_editions = src->num_editions;
        dst->edition = src->edition;
        dst->attachments = src->attachments;
        dst->num_attachments = src->num_attachments;
        dst->matroska_data = src->matroska_data;
        dst->file_contents = src->file_contents;
        dst->playlist = src->playlist;
        dst->seekable = src->seekable;
        dst->filetype = src->filetype;
        dst->ts_resets_possible = src->ts_resets_possible;
        dst->start_time = src->start_time;
    }
    if (src->events & DEMUX_EVENT_STREAMS) {
        // The stream structs themselves are immutable.
        for (int n = dst->num_streams; n < src->num_streams; n++)
            MP_TARRAY_APPEND(dst, dst->streams, dst->num_streams, src->streams[n]);
    }
    if (src->events & DEMUX_EVENT_METADATA) {
        talloc_free(dst->metadata);
        dst->metadata = mp_tags_dup(dst, src->metadata);
    }
    dst->events |= src->events;
    src->events = 0;
}

// This is called by demuxer implementations if certain parameters change
// at runtime.
// events is one of DEMUX_EVENT_*
// The code will copy the fields references by the events to the user-thread.
void demux_changed(demuxer_t *demuxer, int events)
{
    assert(demuxer == demuxer->in->d_thread); // call from demuxer impl. only
    struct demux_internal *in = demuxer->in;

    demuxer->events |= events;

    pthread_mutex_lock(&in->lock);

    update_cache(in);

    if (demuxer->events & DEMUX_EVENT_INIT)
        demuxer_sort_chapters(demuxer);
    if (demuxer->events & (DEMUX_EVENT_METADATA | DEMUX_EVENT_STREAMS))
        demux_export_replaygain(demuxer);

    demux_copy(in->d_buffer, demuxer);

    pthread_mutex_unlock(&in->lock);
}

// Called by the user thread (i.e. player) to update metadata and other things
// from the demuxer thread.
void demux_update(demuxer_t *demuxer)
{
    assert(demuxer == demuxer->in->d_user);
    struct demux_internal *in = demuxer->in;

    pthread_mutex_lock(&in->lock);
    demux_copy(demuxer, in->d_buffer);
    if (in->stream_metadata && (demuxer->events & DEMUX_EVENT_METADATA))
        mp_tags_merge(demuxer->metadata, in->stream_metadata);
    pthread_mutex_unlock(&in->lock);
}

static struct demuxer *open_given_type(struct mpv_global *global,
                                       struct mp_log *log,
                                       const struct demuxer_desc *desc,
                                       struct stream *stream,
                                       struct demuxer_params *params,
                                       enum demux_check check)
{
    struct demuxer *demuxer = talloc_ptrtype(NULL, demuxer);
    *demuxer = (struct demuxer) {
        .desc = desc,
        .type = desc->type,
        .stream = stream,
        .seekable = stream->seekable,
        .filepos = -1,
        .opts = global->opts,
        .global = global,
        .log = mp_log_new(demuxer, log, desc->name),
        .glog = log,
        .filename = talloc_strdup(demuxer, stream->url),
        .events = DEMUX_EVENT_ALL,
    };
    demuxer->seekable = stream->seekable;
    if (demuxer->stream->uncached_stream &&
        !demuxer->stream->uncached_stream->seekable)
        demuxer->seekable = false;

    struct demux_internal *in = demuxer->in = talloc_ptrtype(demuxer, in);
    *in = (struct demux_internal){
        .log = demuxer->log,
        .d_thread = talloc(demuxer, struct demuxer),
        .d_buffer = talloc(demuxer, struct demuxer),
        .d_user = demuxer,
        .min_packs = demuxer->opts->demuxer_min_packs,
        .min_bytes = demuxer->opts->demuxer_min_bytes,
    };
    pthread_mutex_init(&in->lock, NULL);
    pthread_cond_init(&in->wakeup, NULL);

    *in->d_thread = *demuxer;
    *in->d_buffer = *demuxer;

    in->d_thread->metadata = talloc_zero(in->d_thread, struct mp_tags);
    in->d_user->metadata = talloc_zero(in->d_user, struct mp_tags);
    in->d_buffer->metadata = talloc_zero(in->d_buffer, struct mp_tags);

    int64_t start_pos = stream_tell(stream);

    mp_verbose(log, "Trying demuxer: %s (force-level: %s)\n",
               desc->name, d_level(check));

    in->d_thread->params = params; // temporary during open()

    int ret = demuxer->desc->open(in->d_thread, check);
    if (ret >= 0) {
        in->d_thread->params = NULL;
        if (in->d_thread->filetype)
            mp_verbose(log, "Detected file format: %s (%s)\n",
                       in->d_thread->filetype, desc->desc);
        else
            mp_verbose(log, "Detected file format: %s\n", desc->desc);
        // Pretend we can seek if we can't seek, but there's a cache.
        if (!in->d_thread->seekable && stream->uncached_stream) {
            mp_warn(log,
                    "File is not seekable, but there's a cache: enabling seeking.\n");
            in->d_thread->seekable = true;
        }
        demux_changed(in->d_thread, DEMUX_EVENT_ALL);
        demux_update(demuxer);
        return demuxer;
    }

    free_demuxer(demuxer);
    stream_seek(stream, start_pos);
    return NULL;
}

static const int d_normal[]  = {DEMUX_CHECK_NORMAL, DEMUX_CHECK_UNSAFE, -1};
static const int d_request[] = {DEMUX_CHECK_REQUEST, -1};
static const int d_force[]   = {DEMUX_CHECK_FORCE, -1};

struct demuxer *demux_open(struct stream *stream, char *force_format,
                           struct demuxer_params *params,
                           struct mpv_global *global)
{
    const int *check_levels = d_normal;
    const struct demuxer_desc *check_desc = NULL;
    struct mp_log *log = mp_log_new(NULL, global->log, "!demux");
    struct demuxer *demuxer = NULL;

    if (!force_format)
        force_format = stream->demuxer;

    if (force_format && force_format[0]) {
        check_levels = d_request;
        if (force_format[0] == '+') {
            force_format += 1;
            check_levels = d_force;
        }
        for (int n = 0; demuxer_list[n]; n++) {
            if (strcmp(demuxer_list[n]->name, force_format) == 0)
                check_desc = demuxer_list[n];
        }
        if (!check_desc) {
            mp_err(log, "Demuxer %s does not exist.\n", force_format);
            goto done;
        }
    }

    // Peek this much data to avoid that stream_read() run by some demuxers
    // or stream filters will flush previous peeked data.
    stream_peek(stream, STREAM_BUFFER_SIZE);

    // Test demuxers from first to last, one pass for each check_levels[] entry
    for (int pass = 0; check_levels[pass] != -1; pass++) {
        enum demux_check level = check_levels[pass];
        for (int n = 0; demuxer_list[n]; n++) {
            const struct demuxer_desc *desc = demuxer_list[n];
            if (!check_desc || desc == check_desc) {
                demuxer = open_given_type(global, log, desc, stream, params, level);
                if (demuxer) {
                    talloc_steal(demuxer, log);
                    log = NULL;
                    goto done;
                }
            }
        }
    }

done:
    talloc_free(log);
    return demuxer;
}

void demux_flush(demuxer_t *demuxer)
{
    pthread_mutex_lock(&demuxer->in->lock);
    for (int n = 0; n < demuxer->num_streams; n++)
        ds_flush(demuxer->streams[n]->ds);
    demuxer->in->warned_queue_overflow = false;
    demuxer->in->eof = false;
    demuxer->in->last_eof = false;
    pthread_mutex_unlock(&demuxer->in->lock);
}

int demux_seek(demuxer_t *demuxer, float rel_seek_secs, int flags)
{
    if (!demuxer->seekable) {
        MP_WARN(demuxer, "Cannot seek in this file.\n");
        return 0;
    }

    if (rel_seek_secs == MP_NOPTS_VALUE && (flags & SEEK_ABSOLUTE))
        return 0;

    demux_pause(demuxer);

    // clear the packet queues
    demux_flush(demuxer);

    if (demuxer->desc->seek)
        demuxer->desc->seek(demuxer->in->d_thread, rel_seek_secs, flags);

    demux_unpause(demuxer);

    return 1;
}

char *demux_info_get(demuxer_t *demuxer, const char *opt)
{
    return mp_tags_get_str(demuxer->metadata, opt);
}

struct sh_stream *demuxer_stream_by_demuxer_id(struct demuxer *d,
                                               enum stream_type t, int id)
{
    for (int n = 0; n < d->num_streams; n++) {
        struct sh_stream *s = d->streams[n];
        if (s->type == t && s->demuxer_id == id)
            return d->streams[n];
    }
    return NULL;
}

void demuxer_switch_track(struct demuxer *demuxer, enum stream_type type,
                          struct sh_stream *stream)
{
    assert(!stream || stream->type == type);

    for (int n = 0; n < demuxer->num_streams; n++) {
        struct sh_stream *cur = demuxer->streams[n];
        if (cur->type == type)
            demuxer_select_track(demuxer, cur, cur == stream);
    }
}

void demuxer_select_track(struct demuxer *demuxer, struct sh_stream *stream,
                          bool selected)
{
    // don't flush buffers if stream is already selected / unselected
    pthread_mutex_lock(&demuxer->in->lock);
    bool update = false;
    if (stream->ds->selected != selected) {
        stream->ds->selected = selected;
        stream->ds->active = false;
        ds_flush(stream->ds);
        update = true;
    }
    pthread_mutex_unlock(&demuxer->in->lock);
    if (update)
        demux_control(demuxer, DEMUXER_CTRL_SWITCHED_TRACKS, NULL);
}

void demux_set_stream_autoselect(struct demuxer *demuxer, bool autoselect)
{
    assert(!demuxer->in->threading); // laziness
    demuxer->in->autoselect = autoselect;
}

bool demux_stream_is_selected(struct sh_stream *stream)
{
    if (!stream)
        return false;
    bool r = false;
    pthread_mutex_lock(&stream->ds->in->lock);
    r = stream->ds->selected;
    pthread_mutex_unlock(&stream->ds->in->lock);
    return r;
}

int demuxer_add_attachment(demuxer_t *demuxer, struct bstr name,
                           struct bstr type, struct bstr data)
{
    if (!(demuxer->num_attachments % 32))
        demuxer->attachments = talloc_realloc(demuxer, demuxer->attachments,
                                              struct demux_attachment,
                                              demuxer->num_attachments + 32);

    struct demux_attachment *att =
        demuxer->attachments + demuxer->num_attachments;
    att->name = talloc_strndup(demuxer->attachments, name.start, name.len);
    att->type = talloc_strndup(demuxer->attachments, type.start, type.len);
    att->data = talloc_size(demuxer->attachments, data.len);
    memcpy(att->data, data.start, data.len);
    att->data_size = data.len;

    return demuxer->num_attachments++;
}

static int chapter_compare(const void *p1, const void *p2)
{
    struct demux_chapter *c1 = (void *)p1;
    struct demux_chapter *c2 = (void *)p2;

    if (c1->start > c2->start)
        return 1;
    else if (c1->start < c2->start)
        return -1;
    return c1->original_index > c2->original_index ? 1 :-1; // never equal
}

static void demuxer_sort_chapters(demuxer_t *demuxer)
{
    qsort(demuxer->chapters, demuxer->num_chapters,
          sizeof(struct demux_chapter), chapter_compare);
}

int demuxer_add_chapter(demuxer_t *demuxer, struct bstr name,
                        uint64_t start, uint64_t end, uint64_t demuxer_id)
{
    struct demux_chapter new = {
        .original_index = demuxer->num_chapters,
        .start = start,
        .end = end,
        .name = name.len ? bstrdup0(demuxer, name) : NULL,
        .metadata = talloc_zero(demuxer, struct mp_tags),
        .demuxer_id = demuxer_id,
    };
    mp_tags_set_bstr(new.metadata, bstr0("TITLE"), name);
    MP_TARRAY_APPEND(demuxer, demuxer->chapters, demuxer->num_chapters, new);
    return demuxer->num_chapters - 1;
}

double demuxer_get_time_length(struct demuxer *demuxer)
{
    double len;
    if (demux_control(demuxer, DEMUXER_CTRL_GET_TIME_LENGTH, &len) > 0)
        return len;
    return -1;
}

// must be called locked
static void update_cache(struct demux_internal *in)
{
    struct demuxer *demuxer = in->d_thread;
    struct stream *stream = demuxer->stream;

    in->time_length = -1;
    if (demuxer->desc->control) {
        demuxer->desc->control(demuxer, DEMUXER_CTRL_GET_TIME_LENGTH,
                               &in->time_length);
    }

    struct mp_tags *s_meta = NULL;
    stream_control(stream, STREAM_CTRL_GET_METADATA, &s_meta);
    if (s_meta) {
        talloc_free(in->stream_metadata);
        in->stream_metadata = talloc_steal(in, s_meta);
        in->d_buffer->events |= DEMUX_EVENT_METADATA;
    }

    in->stream_size = -1;
    stream_control(stream, STREAM_CTRL_GET_SIZE, &in->stream_size);
    in->stream_cache_size = -1;
    stream_control(stream, STREAM_CTRL_GET_CACHE_SIZE, &in->stream_cache_size);
    in->stream_cache_fill = -1;
    stream_control(stream, STREAM_CTRL_GET_CACHE_FILL, &in->stream_cache_fill);
    in->stream_cache_idle = -1;
    stream_control(stream, STREAM_CTRL_GET_CACHE_IDLE, &in->stream_cache_idle);
}

// must be called locked
static int cached_stream_control(struct demux_internal *in, int cmd, void *arg)
{
    switch (cmd) {
    case STREAM_CTRL_GET_CACHE_SIZE:
        if (in->stream_cache_size < 0)
            return STREAM_UNSUPPORTED;
        *(int64_t *)arg = in->stream_cache_size;
        return STREAM_OK;
    case STREAM_CTRL_GET_CACHE_FILL:
        if (in->stream_cache_fill < 0)
            return STREAM_UNSUPPORTED;
        *(int64_t *)arg = in->stream_cache_fill;
        return STREAM_OK;
    case STREAM_CTRL_GET_CACHE_IDLE:
        if (in->stream_cache_idle < 0)
            return STREAM_UNSUPPORTED;
        *(int *)arg = in->stream_cache_idle;
        return STREAM_OK;
    case STREAM_CTRL_GET_SIZE:
        if (in->stream_size < 0)
            return STREAM_UNSUPPORTED;
        *(int64_t *)arg = in->stream_size;
        return STREAM_OK;
    }
    return STREAM_ERROR;
}

// must be called locked
static int cached_demux_control(struct demux_internal *in, int cmd, void *arg)
{
    switch (cmd) {
    case DEMUXER_CTRL_GET_TIME_LENGTH:
        if (in->time_length < 0)
            return DEMUXER_CTRL_NOTIMPL;
        *(double *)arg = in->time_length;
        return DEMUXER_CTRL_OK;
    case DEMUXER_CTRL_STREAM_CTRL: {
        struct demux_ctrl_stream_ctrl *c = arg;
        int r = cached_stream_control(in, c->ctrl, c->arg);
        if (r == STREAM_ERROR)
            break;
        c->res = r;
        return DEMUXER_CTRL_OK;
    }
    }
    return DEMUXER_CTRL_DONTKNOW;
}

int demux_control(demuxer_t *demuxer, int cmd, void *arg)
{
    struct demux_internal *in = demuxer->in;

    pthread_mutex_lock(&in->lock);
    if (!in->threading)
        update_cache(in);
    int cr = cached_demux_control(in, cmd, arg);
    if (cr != DEMUXER_CTRL_DONTKNOW) {
        pthread_mutex_unlock(&in->lock);
        return cr;
    }
    pthread_mutex_unlock(&in->lock);

    int r = DEMUXER_CTRL_NOTIMPL;
    demux_pause(demuxer);
    if (cmd == DEMUXER_CTRL_STREAM_CTRL) {
        struct demux_ctrl_stream_ctrl *c = arg;
        MP_VERBOSE(demuxer, "blocking for STREAM_CTRL %d\n", c->ctrl);
        c->res = stream_control(demuxer->stream, c->ctrl, c->arg);
        if (c->res != STREAM_UNSUPPORTED)
            r = DEMUXER_CTRL_OK;
    }
    if (r != DEMUXER_CTRL_OK) {
        MP_VERBOSE(demuxer, "blocking for DEMUXER_CTRL %d\n", cmd);
        if (demuxer->desc->control)
            r = demuxer->desc->control(demuxer->in->d_thread, cmd, arg);
    }
    demux_unpause(demuxer);
    return r;
}

int demux_stream_control(demuxer_t *demuxer, int ctrl, void *arg)
{
    struct demux_ctrl_stream_ctrl c = {ctrl, arg, STREAM_UNSUPPORTED};
    demux_control(demuxer, DEMUXER_CTRL_STREAM_CTRL, &c);
    return c.res;
}

// Make the demuxer thread stop doing anything.
// demux_unpause() wakes up the thread again.
// Can be nested with other calls, but trying to read packets may deadlock.
void demux_pause(demuxer_t *demuxer)
{
    struct demux_internal *in = demuxer->in;
    assert(demuxer == in->d_user);

    MP_VERBOSE(in, "pause demux thread\n");

    pthread_mutex_lock(&in->lock);
    in->thread_request_pause++;
    pthread_cond_signal(&in->wakeup);
    while (in->threading && !in->thread_paused)
        pthread_cond_wait(&in->wakeup, &in->lock);
    pthread_mutex_unlock(&in->lock);
}

void demux_unpause(demuxer_t *demuxer)
{
    struct demux_internal *in = demuxer->in;
    assert(demuxer == in->d_user);

    pthread_mutex_lock(&in->lock);
    assert(in->thread_request_pause > 0);
    in->thread_request_pause--;
    pthread_cond_signal(&in->wakeup);
    pthread_mutex_unlock(&in->lock);
}