pulse_audio_enc.c

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/*
 * Copyright (c) 2013 Lukasz Marek <lukasz.m.luki@gmail.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
 
#include <math.h>
#include <pulse/pulseaudio.h>
#include <pulse/error.h>
#include "libavformat/avformat.h"
#include "libavformat/internal.h"
#include "libavformat/mux.h"
#include "libavformat/version.h"
#include "libavutil/channel_layout.h"
#include "libavutil/frame.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "libavutil/time.h"
#include "libavutil/log.h"
#include "libavutil/attributes.h"
#include "pulse_audio_common.h"
 
typedef struct PulseData {
    AVClass *class;
    const char *server;
    const char *name;
    const char *stream_name;
    const char *device;
    int64_t timestamp;
    int buffer_size;               /**< Buffer size in bytes */
    int buffer_duration;           /**< Buffer size in ms, recalculated to buffer_size */
    int prebuf;
    int minreq;
    int last_result;
    pa_threaded_mainloop *mainloop;
    pa_context *ctx;
    pa_stream *stream;
    int nonblocking;
    int mute;
    pa_volume_t base_volume;
    pa_volume_t last_volume;
} PulseData;
 
static void pulse_audio_sink_device_cb(pa_context *ctx, const pa_sink_info *dev,
                                       int eol, void *userdata)
{
    PulseData *s = userdata;
 
    if (s->ctx != ctx)
        return;
 
    if (eol) {
        pa_threaded_mainloop_signal(s->mainloop, 0);
    } else {
        if (dev->flags & PA_SINK_FLAT_VOLUME)
            s->base_volume = dev->base_volume;
        else
            s->base_volume = PA_VOLUME_NORM;
        av_log(s, AV_LOG_DEBUG, "base volume: %u\n", s->base_volume);
    }
}
 
/* Mainloop must be locked before calling this function as it uses pa_threaded_mainloop_wait. */
static int pulse_update_sink_info(AVFormatContext *h)
{
    PulseData *s = h->priv_data;
    pa_operation *op;
    if (!(op = pa_context_get_sink_info_by_name(s->ctx, s->device,
                                                pulse_audio_sink_device_cb, s))) {
        av_log(s, AV_LOG_ERROR, "pa_context_get_sink_info_by_name failed.\n");
        return AVERROR_EXTERNAL;
    }
    while (pa_operation_get_state(op) == PA_OPERATION_RUNNING)
        pa_threaded_mainloop_wait(s->mainloop);
    pa_operation_unref(op);
    return 0;
}
 
static void pulse_audio_sink_input_cb(pa_context *ctx, const pa_sink_input_info *i,
                                      int eol, void *userdata)
{
    AVFormatContext *h = userdata;
    PulseData *s = h->priv_data;
 
    if (s->ctx != ctx)
        return;
 
    if (!eol) {
        double val;
        pa_volume_t vol = pa_cvolume_avg(&i->volume);
        if (s->mute < 0 || (s->mute && !i->mute) || (!s->mute && i->mute)) {
            s->mute = i->mute;
            avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_MUTE_STATE_CHANGED, &s->mute, sizeof(s->mute));
        }
 
        vol = pa_sw_volume_divide(vol, s->base_volume);
        if (s->last_volume != vol) {
            val = (double)vol / PA_VOLUME_NORM;
            avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_VOLUME_LEVEL_CHANGED, &val, sizeof(val));
            s->last_volume = vol;
        }
    }
}
 
/* This function creates new loop so may be called from PA callbacks.
   Mainloop must be locked before calling this function as it operates on streams. */
static int pulse_update_sink_input_info(AVFormatContext *h)
{
    PulseData *s = h->priv_data;
    pa_operation *op;
    enum pa_operation_state op_state;
    pa_mainloop *ml = NULL;
    pa_context *ctx = NULL;
    int ret = 0;
 
    if ((ret = ff_pulse_audio_connect_context(&ml, &ctx, s->server, "Update sink input information")) < 0)
        return ret;
 
    if (!(op = pa_context_get_sink_input_info(ctx, pa_stream_get_index(s->stream),
                                              pulse_audio_sink_input_cb, h))) {
        ret = AVERROR_EXTERNAL;
        goto fail;
    }
 
    while ((op_state = pa_operation_get_state(op)) == PA_OPERATION_RUNNING)
        pa_mainloop_iterate(ml, 1, NULL);
    pa_operation_unref(op);
    if (op_state != PA_OPERATION_DONE) {
        ret = AVERROR_EXTERNAL;
        goto fail;
    }
 
  fail:
    ff_pulse_audio_disconnect_context(&ml, &ctx);
    if (ret)
        av_log(s, AV_LOG_ERROR, "pa_context_get_sink_input_info failed.\n");
    return ret;
}
 
static void pulse_event(pa_context *ctx, pa_subscription_event_type_t t,
                        uint32_t idx, void *userdata)
{
    AVFormatContext *h = userdata;
    PulseData *s = h->priv_data;
 
    if (s->ctx != ctx)
        return;
 
    if ((t & PA_SUBSCRIPTION_EVENT_FACILITY_MASK) == PA_SUBSCRIPTION_EVENT_SINK_INPUT) {
        if ((t & PA_SUBSCRIPTION_EVENT_TYPE_MASK) == PA_SUBSCRIPTION_EVENT_CHANGE)
            // Calling from mainloop callback. No need to lock mainloop.
            pulse_update_sink_input_info(h);
    }
}
 
static void pulse_stream_writable(pa_stream *stream, size_t nbytes, void *userdata)
{
    AVFormatContext *h = userdata;
    PulseData *s = h->priv_data;
    int64_t val = nbytes;
 
    if (stream != s->stream)
        return;
 
    avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_BUFFER_WRITABLE, &val, sizeof(val));
    pa_threaded_mainloop_signal(s->mainloop, 0);
}
 
static void pulse_overflow(pa_stream *stream, void *userdata)
{
    AVFormatContext *h = userdata;
    avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_BUFFER_OVERFLOW, NULL, 0);
}
 
static void pulse_underflow(pa_stream *stream, void *userdata)
{
    AVFormatContext *h = userdata;
    avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_BUFFER_UNDERFLOW, NULL, 0);
}
 
static void pulse_stream_state(pa_stream *stream, void *userdata)
{
    PulseData *s = userdata;
 
    if (stream != s->stream)
        return;
 
    switch (pa_stream_get_state(s->stream)) {
        case PA_STREAM_READY:
        case PA_STREAM_FAILED:
        case PA_STREAM_TERMINATED:
            pa_threaded_mainloop_signal(s->mainloop, 0);
        default:
            break;
    }
}
 
static int pulse_stream_wait(PulseData *s)
{
    pa_stream_state_t state;
 
    while ((state = pa_stream_get_state(s->stream)) != PA_STREAM_READY) {
        if (state == PA_STREAM_FAILED || state == PA_STREAM_TERMINATED)
            return AVERROR_EXTERNAL;
        pa_threaded_mainloop_wait(s->mainloop);
    }
    return 0;
}
 
static void pulse_context_state(pa_context *ctx, void *userdata)
{
    PulseData *s = userdata;
 
    if (s->ctx != ctx)
        return;
 
    switch (pa_context_get_state(ctx)) {
        case PA_CONTEXT_READY:
        case PA_CONTEXT_FAILED:
        case PA_CONTEXT_TERMINATED:
            pa_threaded_mainloop_signal(s->mainloop, 0);
        default:
            break;
    }
}
 
static int pulse_context_wait(PulseData *s)
{
    pa_context_state_t state;
 
    while ((state = pa_context_get_state(s->ctx)) != PA_CONTEXT_READY) {
        if (state == PA_CONTEXT_FAILED || state == PA_CONTEXT_TERMINATED)
            return AVERROR_EXTERNAL;
        pa_threaded_mainloop_wait(s->mainloop);
    }
    return 0;
}
 
static void pulse_stream_result(pa_stream *stream, int success, void *userdata)
{
    PulseData *s = userdata;
 
    if (stream != s->stream)
        return;
 
    s->last_result = success ? 0 : AVERROR_EXTERNAL;
    pa_threaded_mainloop_signal(s->mainloop, 0);
}
 
static int pulse_finish_stream_operation(PulseData *s, pa_operation *op, const char *name)
{
    if (!op) {
        pa_threaded_mainloop_unlock(s->mainloop);
        av_log(s, AV_LOG_ERROR, "%s failed.\n", name);
        return AVERROR_EXTERNAL;
    }
    s->last_result = 2;
    while (s->last_result == 2)
        pa_threaded_mainloop_wait(s->mainloop);
    pa_operation_unref(op);
    pa_threaded_mainloop_unlock(s->mainloop);
    if (s->last_result != 0)
        av_log(s, AV_LOG_ERROR, "%s failed.\n", name);
    return s->last_result;
}
 
static int pulse_set_pause(PulseData *s, int pause)
{
    pa_operation *op;
    pa_threaded_mainloop_lock(s->mainloop);
    op = pa_stream_cork(s->stream, pause, pulse_stream_result, s);
    return pulse_finish_stream_operation(s, op, "pa_stream_cork");
}
 
static int pulse_flash_stream(PulseData *s)
{
    pa_operation *op;
    pa_threaded_mainloop_lock(s->mainloop);
    op = pa_stream_flush(s->stream, pulse_stream_result, s);
    return pulse_finish_stream_operation(s, op, "pa_stream_flush");
}
 
static void pulse_context_result(pa_context *ctx, int success, void *userdata)
{
    PulseData *s = userdata;
 
    if (s->ctx != ctx)
        return;
 
    s->last_result = success ? 0 : AVERROR_EXTERNAL;
    pa_threaded_mainloop_signal(s->mainloop, 0);
}
 
static int pulse_finish_context_operation(PulseData *s, pa_operation *op, const char *name)
{
    if (!op) {
        pa_threaded_mainloop_unlock(s->mainloop);
        av_log(s, AV_LOG_ERROR, "%s failed.\n", name);
        return AVERROR_EXTERNAL;
    }
    s->last_result = 2;
    while (s->last_result == 2)
        pa_threaded_mainloop_wait(s->mainloop);
    pa_operation_unref(op);
    pa_threaded_mainloop_unlock(s->mainloop);
    if (s->last_result != 0)
        av_log(s, AV_LOG_ERROR, "%s failed.\n", name);
    return s->last_result;
}
 
static int pulse_set_mute(PulseData *s)
{
    pa_operation *op;
    pa_threaded_mainloop_lock(s->mainloop);
    op = pa_context_set_sink_input_mute(s->ctx, pa_stream_get_index(s->stream),
                                        s->mute, pulse_context_result, s);
    return pulse_finish_context_operation(s, op, "pa_context_set_sink_input_mute");
}
 
static int pulse_set_volume(PulseData *s, double volume)
{
    pa_operation *op;
    pa_cvolume cvol;
    pa_volume_t vol;
    const pa_sample_spec *ss = pa_stream_get_sample_spec(s->stream);
 
    vol = pa_sw_volume_multiply(lrint(volume * PA_VOLUME_NORM), s->base_volume);
    pa_cvolume_set(&cvol, ss->channels, PA_VOLUME_NORM);
    pa_sw_cvolume_multiply_scalar(&cvol, &cvol, vol);
    pa_threaded_mainloop_lock(s->mainloop);
    op = pa_context_set_sink_input_volume(s->ctx, pa_stream_get_index(s->stream),
                                          &cvol, pulse_context_result, s);
    return pulse_finish_context_operation(s, op, "pa_context_set_sink_input_volume");
}
 
static int pulse_subscribe_events(PulseData *s)
{
    pa_operation *op;
 
    pa_threaded_mainloop_lock(s->mainloop);
    op = pa_context_subscribe(s->ctx, PA_SUBSCRIPTION_MASK_SINK_INPUT, pulse_context_result, s);
    return pulse_finish_context_operation(s, op, "pa_context_subscribe");
}
 
static void pulse_map_channels_to_pulse(const AVChannelLayout *channel_layout, pa_channel_map *channel_map)
{
    channel_map->channels = 0;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_FRONT_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_FRONT_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_FRONT_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_LOW_FREQUENCY) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_LFE;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_BACK_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_REAR_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_BACK_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_REAR_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_FRONT_LEFT_OF_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_FRONT_RIGHT_OF_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_BACK_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_REAR_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_SIDE_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_SIDE_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_SIDE_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_SIDE_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_FRONT_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_FRONT_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_FRONT_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_FRONT_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_FRONT_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_FRONT_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_BACK_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_REAR_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_BACK_CENTER) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_REAR_CENTER;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_TOP_BACK_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_TOP_REAR_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_STEREO_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_LEFT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_STEREO_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_FRONT_RIGHT;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_WIDE_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_AUX0;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_WIDE_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_AUX1;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_SURROUND_DIRECT_LEFT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_AUX2;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_SURROUND_DIRECT_RIGHT) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_AUX3;
    if (av_channel_layout_index_from_channel(channel_layout, AV_CHAN_LOW_FREQUENCY_2) >= 0)
        channel_map->map[channel_map->channels++] = PA_CHANNEL_POSITION_LFE;
}
 
static av_cold int pulse_write_trailer(AVFormatContext *h)
{
    PulseData *s = h->priv_data;
 
    if (s->mainloop) {
        pa_threaded_mainloop_lock(s->mainloop);
        if (s->stream) {
            pa_stream_disconnect(s->stream);
            pa_stream_set_state_callback(s->stream, NULL, NULL);
            pa_stream_set_write_callback(s->stream, NULL, NULL);
            pa_stream_set_overflow_callback(s->stream, NULL, NULL);
            pa_stream_set_underflow_callback(s->stream, NULL, NULL);
            pa_stream_unref(s->stream);
            s->stream = NULL;
        }
        if (s->ctx) {
            pa_context_disconnect(s->ctx);
            pa_context_set_state_callback(s->ctx, NULL, NULL);
            pa_context_set_subscribe_callback(s->ctx, NULL, NULL);
            pa_context_unref(s->ctx);
            s->ctx = NULL;
        }
        pa_threaded_mainloop_unlock(s->mainloop);
        pa_threaded_mainloop_stop(s->mainloop);
        pa_threaded_mainloop_free(s->mainloop);
        s->mainloop = NULL;
    }
 
    return 0;
}
 
static av_cold int pulse_write_header(AVFormatContext *h)
{
    PulseData *s = h->priv_data;
    AVStream *st = NULL;
    int ret;
    pa_sample_spec sample_spec;
    pa_buffer_attr buffer_attributes = { -1, -1, -1, -1, -1 };
    pa_channel_map channel_map;
    pa_mainloop_api *mainloop_api;
    const char *stream_name = s->stream_name;
    static const pa_stream_flags_t stream_flags = PA_STREAM_INTERPOLATE_TIMING |
                                                  PA_STREAM_AUTO_TIMING_UPDATE |
                                                  PA_STREAM_NOT_MONOTONIC;
 
    if (h->nb_streams != 1 || h->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO) {
        av_log(s, AV_LOG_ERROR, "Only a single audio stream is supported.\n");
        return AVERROR(EINVAL);
    }
    st = h->streams[0];
 
    if (!stream_name) {
        if (h->url[0])
            stream_name = h->url;
        else
            stream_name = "Playback";
    }
    s->nonblocking = (h->flags & AVFMT_FLAG_NONBLOCK);
 
    if (s->buffer_duration) {
        int64_t bytes = s->buffer_duration;
        bytes *= st->codecpar->ch_layout.nb_channels * st->codecpar->sample_rate *
                 av_get_bytes_per_sample(st->codecpar->format);
        bytes /= 1000;
        buffer_attributes.tlength = FFMAX(s->buffer_size, av_clip64(bytes, 0, UINT32_MAX - 1));
        av_log(s, AV_LOG_DEBUG,
               "Buffer duration: %ums recalculated into %"PRId64" bytes buffer.\n",
               s->buffer_duration, bytes);
        av_log(s, AV_LOG_DEBUG, "Real buffer length is %u bytes\n", buffer_attributes.tlength);
    } else if (s->buffer_size)
        buffer_attributes.tlength = s->buffer_size;
    if (s->prebuf)
        buffer_attributes.prebuf = s->prebuf;
    if (s->minreq)
        buffer_attributes.minreq = s->minreq;
 
    sample_spec.format = ff_codec_id_to_pulse_format(st->codecpar->codec_id);
    sample_spec.rate = st->codecpar->sample_rate;
    sample_spec.channels = st->codecpar->ch_layout.nb_channels;
    if (!pa_sample_spec_valid(&sample_spec)) {
        av_log(s, AV_LOG_ERROR, "Invalid sample spec.\n");
        return AVERROR(EINVAL);
    }
 
    if (sample_spec.channels == 1) {
        channel_map.channels = 1;
        channel_map.map[0] = PA_CHANNEL_POSITION_MONO;
    } else if (st->codecpar->ch_layout.order != AV_CHANNEL_ORDER_UNSPEC) {
        if (!av_channel_layout_check(&st->codecpar->ch_layout))
            return AVERROR(EINVAL);
        pulse_map_channels_to_pulse(&st->codecpar->ch_layout, &channel_map);
        /* Unknown channel is present in channel_layout, let PulseAudio use its default. */
        if (channel_map.channels != sample_spec.channels) {
            av_log(s, AV_LOG_WARNING, "Unknown channel. Using default channel map.\n");
            channel_map.channels = 0;
        }
    } else
        channel_map.channels = 0;
 
    if (!channel_map.channels)
        av_log(s, AV_LOG_WARNING, "Using PulseAudio's default channel map.\n");
    else if (!pa_channel_map_valid(&channel_map)) {
        av_log(s, AV_LOG_ERROR, "Invalid channel map.\n");
        return AVERROR(EINVAL);
    }
 
    /* start main loop */
    s->mainloop = pa_threaded_mainloop_new();
    if (!s->mainloop) {
        av_log(s, AV_LOG_ERROR, "Cannot create threaded mainloop.\n");
        return AVERROR(ENOMEM);
    }
    if ((ret = pa_threaded_mainloop_start(s->mainloop)) < 0) {
        av_log(s, AV_LOG_ERROR, "Cannot start threaded mainloop: %s.\n", pa_strerror(ret));
        pa_threaded_mainloop_free(s->mainloop);
        s->mainloop = NULL;
        return AVERROR_EXTERNAL;
    }
 
    pa_threaded_mainloop_lock(s->mainloop);
 
    mainloop_api = pa_threaded_mainloop_get_api(s->mainloop);
    if (!mainloop_api) {
        av_log(s, AV_LOG_ERROR, "Cannot get mainloop API.\n");
        ret = AVERROR_EXTERNAL;
        goto fail;
    }
 
    s->ctx = pa_context_new(mainloop_api, s->name);
    if (!s->ctx) {
        av_log(s, AV_LOG_ERROR, "Cannot create context.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }
    pa_context_set_state_callback(s->ctx, pulse_context_state, s);
    pa_context_set_subscribe_callback(s->ctx, pulse_event, h);
 
    if ((ret = pa_context_connect(s->ctx, s->server, 0, NULL)) < 0) {
        av_log(s, AV_LOG_ERROR, "Cannot connect context: %s.\n", pa_strerror(ret));
        ret = AVERROR_EXTERNAL;
        goto fail;
    }
 
    if ((ret = pulse_context_wait(s)) < 0) {
        av_log(s, AV_LOG_ERROR, "Context failed.\n");
        goto fail;
    }
 
    s->stream = pa_stream_new(s->ctx, stream_name, &sample_spec,
                              channel_map.channels ? &channel_map : NULL);
 
    if ((ret = pulse_update_sink_info(h)) < 0) {
        av_log(s, AV_LOG_ERROR, "Updating sink info failed.\n");
        goto fail;
    }
 
    if (!s->stream) {
        av_log(s, AV_LOG_ERROR, "Cannot create stream.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }
    pa_stream_set_state_callback(s->stream, pulse_stream_state, s);
    pa_stream_set_write_callback(s->stream, pulse_stream_writable, h);
    pa_stream_set_overflow_callback(s->stream, pulse_overflow, h);
    pa_stream_set_underflow_callback(s->stream, pulse_underflow, h);
 
    if ((ret = pa_stream_connect_playback(s->stream, s->device, &buffer_attributes,
                                          stream_flags, NULL, NULL)) < 0) {
        av_log(s, AV_LOG_ERROR, "pa_stream_connect_playback failed: %s.\n", pa_strerror(ret));
        ret = AVERROR_EXTERNAL;
        goto fail;
    }
 
    if ((ret = pulse_stream_wait(s)) < 0) {
        av_log(s, AV_LOG_ERROR, "Stream failed.\n");
        goto fail;
    }
 
    /* read back buffer attributes for future use */
    buffer_attributes = *pa_stream_get_buffer_attr(s->stream);
    s->buffer_size = buffer_attributes.tlength;
    s->prebuf = buffer_attributes.prebuf;
    s->minreq = buffer_attributes.minreq;
    av_log(s, AV_LOG_DEBUG, "Real buffer attributes: size: %d, prebuf: %d, minreq: %d\n",
           s->buffer_size, s->prebuf, s->minreq);
 
    pa_threaded_mainloop_unlock(s->mainloop);
 
    if ((ret = pulse_subscribe_events(s)) < 0) {
        av_log(s, AV_LOG_ERROR, "Event subscription failed.\n");
        /* a bit ugly but the simplest to lock here*/
        pa_threaded_mainloop_lock(s->mainloop);
        goto fail;
    }
 
    /* force control messages */
    s->mute = -1;
    s->last_volume = PA_VOLUME_INVALID;
    pa_threaded_mainloop_lock(s->mainloop);
    if ((ret = pulse_update_sink_input_info(h)) < 0) {
        av_log(s, AV_LOG_ERROR, "Updating sink input info failed.\n");
        goto fail;
    }
    pa_threaded_mainloop_unlock(s->mainloop);
 
    avpriv_set_pts_info(st, 64, 1, 1000000);  /* 64 bits pts in us */
 
    return 0;
  fail:
    pa_threaded_mainloop_unlock(s->mainloop);
    pulse_write_trailer(h);
    return ret;
}
 
static int pulse_write_packet(AVFormatContext *h, AVPacket *pkt)
{
    PulseData *s = h->priv_data;
    int ret;
    int64_t writable_size;
 
    if (!pkt)
        return pulse_flash_stream(s);
 
    if (pkt->dts != AV_NOPTS_VALUE)
        s->timestamp = pkt->dts;
 
    if (pkt->duration) {
        s->timestamp += pkt->duration;
    } else {
        AVStream *st = h->streams[0];
        AVRational r = { 1, st->codecpar->sample_rate };
        int64_t samples = pkt->size / (av_get_bytes_per_sample(st->codecpar->format) * st->codecpar->ch_layout.nb_channels);
        s->timestamp += av_rescale_q(samples, r, st->time_base);
    }
 
    pa_threaded_mainloop_lock(s->mainloop);
    if (!PA_STREAM_IS_GOOD(pa_stream_get_state(s->stream))) {
        av_log(s, AV_LOG_ERROR, "PulseAudio stream is in invalid state.\n");
        goto fail;
    }
    while (pa_stream_writable_size(s->stream) < s->minreq) {
        if (s->nonblocking) {
            pa_threaded_mainloop_unlock(s->mainloop);
            return AVERROR(EAGAIN);
        } else
            pa_threaded_mainloop_wait(s->mainloop);
    }
 
    if ((ret = pa_stream_write(s->stream, pkt->data, pkt->size, NULL, 0, PA_SEEK_RELATIVE)) < 0) {
        av_log(s, AV_LOG_ERROR, "pa_stream_write failed: %s\n", pa_strerror(ret));
        goto fail;
    }
    if ((writable_size = pa_stream_writable_size(s->stream)) >= s->minreq)
        avdevice_dev_to_app_control_message(h, AV_DEV_TO_APP_BUFFER_WRITABLE, &writable_size, sizeof(writable_size));
 
    pa_threaded_mainloop_unlock(s->mainloop);
 
    return 0;
  fail:
    pa_threaded_mainloop_unlock(s->mainloop);
    return AVERROR_EXTERNAL;
}
 
static int pulse_write_frame(AVFormatContext *h, int stream_index,
                             AVFrame **frame, unsigned flags)
{
    AVPacket pkt;
 
    /* Planar formats are not supported yet. */
    if (flags & AV_WRITE_UNCODED_FRAME_QUERY)
        return av_sample_fmt_is_planar(h->streams[stream_index]->codecpar->format) ?
               AVERROR(EINVAL) : 0;
 
    pkt.data     = (*frame)->data[0];
    pkt.size     = (*frame)->nb_samples * av_get_bytes_per_sample((*frame)->format) * (*frame)->ch_layout.nb_channels;
    pkt.dts      = (*frame)->pkt_dts;
    pkt.duration = (*frame)->duration;
    return pulse_write_packet(h, &pkt);
}
 
 
static void pulse_get_output_timestamp(AVFormatContext *h, int stream, int64_t *dts, int64_t *wall)
{
    PulseData *s = h->priv_data;
    pa_usec_t latency;
    int neg;
    pa_threaded_mainloop_lock(s->mainloop);
    pa_stream_get_latency(s->stream, &latency, &neg);
    pa_threaded_mainloop_unlock(s->mainloop);
    if (wall)
        *wall = av_gettime();
    if (dts)
        *dts = s->timestamp - (neg ? -latency : latency);
}
 
static int pulse_get_device_list(AVFormatContext *h, AVDeviceInfoList *device_list)
{
    PulseData *s = h->priv_data;
    return ff_pulse_audio_get_devices(device_list, s->server, 1);
}
 
static int pulse_control_message(AVFormatContext *h, int type,
                                 void *data, size_t data_size)
{
    PulseData *s = h->priv_data;
    int ret;
 
    switch(type) {
    case AV_APP_TO_DEV_PAUSE:
        return pulse_set_pause(s, 1);
    case AV_APP_TO_DEV_PLAY:
        return pulse_set_pause(s, 0);
    case AV_APP_TO_DEV_TOGGLE_PAUSE:
        return pulse_set_pause(s, !pa_stream_is_corked(s->stream));
    case AV_APP_TO_DEV_MUTE:
        if (!s->mute) {
            s->mute = 1;
            return pulse_set_mute(s);
        }
        return 0;
    case AV_APP_TO_DEV_UNMUTE:
        if (s->mute) {
            s->mute = 0;
            return pulse_set_mute(s);
        }
        return 0;
    case AV_APP_TO_DEV_TOGGLE_MUTE:
        s->mute = !s->mute;
        return pulse_set_mute(s);
    case AV_APP_TO_DEV_SET_VOLUME:
        return pulse_set_volume(s, *(double *)data);
    case AV_APP_TO_DEV_GET_VOLUME:
        s->last_volume = PA_VOLUME_INVALID;
        pa_threaded_mainloop_lock(s->mainloop);
        ret = pulse_update_sink_input_info(h);
        pa_threaded_mainloop_unlock(s->mainloop);
        return ret;
    case AV_APP_TO_DEV_GET_MUTE:
        s->mute = -1;
        pa_threaded_mainloop_lock(s->mainloop);
        ret = pulse_update_sink_input_info(h);
        pa_threaded_mainloop_unlock(s->mainloop);
        return ret;
    default:
        break;
    }
    return AVERROR(ENOSYS);
}
 
#define OFFSET(a) offsetof(PulseData, a)
#define E AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "server",          "set PulseAudio server",            OFFSET(server),          AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
    { "name",            "set application name",             OFFSET(name),            AV_OPT_TYPE_STRING, {.str = LIBAVFORMAT_IDENT},  0, 0, E },
    { "stream_name",     "set stream description",           OFFSET(stream_name),     AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
    { "device",          "set device name",                  OFFSET(device),          AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
    { "buffer_size",     "set buffer size in bytes",         OFFSET(buffer_size),     AV_OPT_TYPE_INT,    {.i64 = 0}, 0, INT_MAX, E },
    { "buffer_duration", "set buffer duration in millisecs", OFFSET(buffer_duration), AV_OPT_TYPE_INT,    {.i64 = 0}, 0, INT_MAX, E },
    { "prebuf",          "set pre-buffering size",           OFFSET(prebuf),          AV_OPT_TYPE_INT,    {.i64 = 0}, 0, INT_MAX, E },
    { "minreq",          "set minimum request size",         OFFSET(minreq),          AV_OPT_TYPE_INT,    {.i64 = 0}, 0, INT_MAX, E },
    { NULL }
};
 
static const AVClass pulse_muxer_class = {
    .class_name     = "PulseAudio outdev",
    .item_name      = av_default_item_name,
    .option         = options,
    .version        = LIBAVUTIL_VERSION_INT,
    .category       = AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT,
};
 
const FFOutputFormat ff_pulse_muxer = {
    .p.name               = "pulse",
    .p.long_name          = NULL_IF_CONFIG_SMALL("Pulse audio output"),
    .priv_data_size       = sizeof(PulseData),
    .p.audio_codec        = AV_NE(AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE),
    .p.video_codec        = AV_CODEC_ID_NONE,
    .write_header         = pulse_write_header,
    .write_packet         = pulse_write_packet,
    .write_uncoded_frame  = pulse_write_frame,
    .write_trailer        = pulse_write_trailer,
    .get_output_timestamp = pulse_get_output_timestamp,
    .get_device_list      = pulse_get_device_list,
    .control_message      = pulse_control_message,
#if FF_API_ALLOW_FLUSH
    .p.flags              = AVFMT_NOFILE | AVFMT_ALLOW_FLUSH,
#else
    .p.flags              = AVFMT_NOFILE,
#endif
    .p.priv_class         = &pulse_muxer_class,
    .flags_internal       = FF_OFMT_FLAG_ALLOW_FLUSH,
};