一垛孔、初始化

- (id)initWithContentURLString:(NSString *)aUrlString
                   withOptions:(IJKFFOptions *)options
{
    if (aUrlString == nil)
        return nil;

    self = [super init];
    if (self) {
        ijkmp_global_init();
        ijkmp_global_set_inject_callback(ijkff_inject_callback);

        [IJKFFMoviePlayerController checkIfFFmpegVersionMatch:NO];

        if (options == nil)
            options = [IJKFFOptions optionsByDefault];

        // IJKFFIOStatRegister(IJKFFIOStatDebugCallback);
        // IJKFFIOStatCompleteRegister(IJKFFIOStatCompleteDebugCallback);

        // init fields
        _scalingMode = IJKMPMovieScalingModeAspectFit;
        _shouldAutoplay = YES;
        memset(&_asyncStat, 0, sizeof(_asyncStat));
        memset(&_cacheStat, 0, sizeof(_cacheStat));
        _monitor = [[IJKFFMonitor alloc] init];

        // init media resource
        _urlString = aUrlString;

        // init player
        _mediaPlayer = ijkmp_ios_create(media_player_msg_loop);
        _msgPool = [[IJKFFMoviePlayerMessagePool alloc] init];
        IJKWeakHolder *weakHolder = [IJKWeakHolder new];
        weakHolder.object = self;

        ijkmp_set_weak_thiz(_mediaPlayer, (__bridge_retained void *) self);
        ijkmp_set_inject_opaque(_mediaPlayer, (__bridge_retained void *) weakHolder);
        ijkmp_set_ijkio_inject_opaque(_mediaPlayer, (__bridge_retained void *)weakHolder);
        ijkmp_set_option_int(_mediaPlayer, IJKMP_OPT_CATEGORY_PLAYER, "start-on-prepared", _shouldAutoplay ? 1 : 0);

        // init video sink
        _glView = [[IJKSDLGLView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        _glView.shouldShowHudView = NO;
        _view   = _glView;
        [_glView setHudValue:nil forKey:@"scheme"];
        [_glView setHudValue:nil forKey:@"host"];
        [_glView setHudValue:nil forKey:@"path"];
        [_glView setHudValue:nil forKey:@"ip"];
        [_glView setHudValue:nil forKey:@"tcp-info"];
        [_glView setHudValue:nil forKey:@"http"];
        [_glView setHudValue:nil forKey:@"tcp-spd"];
        [_glView setHudValue:nil forKey:@"t-prepared"];
        [_glView setHudValue:nil forKey:@"t-render"];
        [_glView setHudValue:nil forKey:@"t-preroll"];
        [_glView setHudValue:nil forKey:@"t-http-open"];
        [_glView setHudValue:nil forKey:@"t-http-seek"];
        
        self.shouldShowHudView = options.showHudView;

        ijkmp_ios_set_glview(_mediaPlayer, _glView);
        ijkmp_set_option(_mediaPlayer, IJKMP_OPT_CATEGORY_PLAYER, "overlay-format", "fcc-_es2");
#ifdef DEBUG
        [IJKFFMoviePlayerController setLogLevel:k_IJK_LOG_DEBUG];
#else
        [IJKFFMoviePlayerController setLogLevel:k_IJK_LOG_SILENT];
#endif
        // init audio sink
        [[IJKAudioKit sharedInstance] setupAudioSession];

        [options applyTo:_mediaPlayer];
        _pauseInBackground = NO;

        // init extra
        _keepScreenOnWhilePlaying = YES;
        [self setScreenOn:YES];

        _notificationManager = [[IJKNotificationManager alloc] init];
        [self registerApplicationObservers];
    }
    return self;
}

二、播放
prepareToPlay為native方法愿伴，映射為ijkmp_prepare_async趟咆，經(jīng)過一系列調(diào)用后會(huì)走到ijkplayer.c的ijkmp_prepare_async_l方法里面：

    ijkmp_change_state_l(mp, MP_STATE_ASYNC_PREPARING);

    msg_queue_start(&mp->ffplayer->msg_queue);

    // released in msg_loop
    ijkmp_inc_ref(mp);
    mp->msg_thread = SDL_CreateThreadEx(&mp->_msg_thread, ijkmp_msg_loop, mp, "ff_msg_loop");
    // msg_thread is detached inside msg_loop
    // TODO: 9 release weak_thiz if pthread_create() failed;

    int retval = ffp_prepare_async_l(mp->ffplayer, mp->data_source);
    if (retval < 0) {
        ijkmp_change_state_l(mp, MP_STATE_ERROR);
        return retval;
    }

    return 0;

這里顯示啟動(dòng)了一個(gè)隊(duì)列，然后啟動(dòng)了一個(gè)loop消息線程（一個(gè)獨(dú)立的線程來處理消息派發(fā)）渺蒿，然后走了一個(gè)關(guān)鍵函數(shù)ffp_prepare_async_l痢士。重點(diǎn)看下面的ffp_prepare_async_l，這個(gè)才是進(jìn)入到準(zhǔn)備播放的階段：

int ffp_prepare_async_l(FFPlayer *ffp, const char *file_name)
{
    assert(ffp);
    assert(!ffp->is);
    assert(file_name);

    if (av_stristart(file_name, "rtmp", NULL) ||
        av_stristart(file_name, "rtsp", NULL)) {
        // There is total different meaning for 'timeout' option in rtmp
        av_log(ffp, AV_LOG_WARNING, "remove 'timeout' option for rtmp.\n");
        av_dict_set(&ffp->format_opts, "timeout", NULL, 0);
    }

    /* there is a length limit in avformat */
    if (strlen(file_name) + 1 > 1024) {
        av_log(ffp, AV_LOG_ERROR, "%s too long url\n", __func__);
        if (avio_find_protocol_name("ijklongurl:")) {
            av_dict_set(&ffp->format_opts, "ijklongurl-url", file_name, 0);
            file_name = "ijklongurl:";
        }
    }

    av_log(NULL, AV_LOG_INFO, "===== versions =====\n");
    ffp_show_version_str(ffp, "ijkplayer",      ijk_version_info());
    ffp_show_version_str(ffp, "FFmpeg",         av_version_info());
    ffp_show_version_int(ffp, "libavutil",      avutil_version());
    ffp_show_version_int(ffp, "libavcodec",     avcodec_version());
    ffp_show_version_int(ffp, "libavformat",    avformat_version());
    ffp_show_version_int(ffp, "libswscale",     swscale_version());
    ffp_show_version_int(ffp, "libswresample",  swresample_version());
    av_log(NULL, AV_LOG_INFO, "===== options =====\n");
    ffp_show_dict(ffp, "player-opts", ffp->player_opts);
    ffp_show_dict(ffp, "format-opts", ffp->format_opts);
    ffp_show_dict(ffp, "codec-opts ", ffp->codec_opts);
    ffp_show_dict(ffp, "sws-opts   ", ffp->sws_dict);
    ffp_show_dict(ffp, "swr-opts   ", ffp->swr_opts);
    av_log(NULL, AV_LOG_INFO, "===================\n");

    av_opt_set_dict(ffp, &ffp->player_opts);
    if (!ffp->aout) {
        ffp->aout = ffpipeline_open_audio_output(ffp->pipeline, ffp);
        if (!ffp->aout)
            return -1;
    }

#if CONFIG_AVFILTER
    if (ffp->vfilter0) {
        GROW_ARRAY(ffp->vfilters_list, ffp->nb_vfilters);
        ffp->vfilters_list[ffp->nb_vfilters - 1] = ffp->vfilter0;
    }
#endif

    VideoState *is = stream_open(ffp, file_name, NULL);
    if (!is) {
        av_log(NULL, AV_LOG_WARNING, "ffp_prepare_async_l: stream_open failed OOM");
        return EIJK_OUT_OF_MEMORY;
    }

    ffp->is = is;
    ffp->input_filename = av_strdup(file_name);
    return 0;
}

前面判斷直播視頻流協(xié)議rtmp或rtsp茂装，再后面基本是輸出信息的怠蹂，真正的核心函數(shù)是stream_open。這個(gè)才是根據(jù)地址打開視頻流少态，代碼如下：

static VideoState *stream_open(FFPlayer *ffp, const char *filename, AVInputFormat *iformat)
{
    assert(!ffp->is);
    VideoState *is;

    is = av_mallocz(sizeof(VideoState));
    if (!is)
        return NULL;
    is->filename = av_strdup(filename);
    if (!is->filename)
        goto fail;
    is->iformat = iformat;
    is->ytop    = 0;
    is->xleft   = 0;
#if defined(__ANDROID__)
    if (ffp->soundtouch_enable) {
        is->handle = ijk_soundtouch_create();
    }
#endif
    /* start video display */
    if (frame_queue_init(&is->pictq, &is->videoq, ffp->pictq_size, 1) < 0)
        goto fail;
    if (frame_queue_init(&is->subpq, &is->subtitleq, SUBPICTURE_QUEUE_SIZE, 0) < 0)
        goto fail;
    if (frame_queue_init(&is->sampq, &is->audioq, SAMPLE_QUEUE_SIZE, 1) < 0)
        goto fail;

    if (packet_queue_init(&is->videoq) < 0 ||
        packet_queue_init(&is->audioq) < 0 ||
        packet_queue_init(&is->subtitleq) < 0)
        goto fail;

    if (!(is->continue_read_thread = SDL_CreateCond())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        goto fail;
    }

    if (!(is->video_accurate_seek_cond = SDL_CreateCond())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        ffp->enable_accurate_seek = 0;
    }

    if (!(is->audio_accurate_seek_cond = SDL_CreateCond())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        ffp->enable_accurate_seek = 0;
    }

    init_clock(&is->vidclk, &is->videoq.serial);
    init_clock(&is->audclk, &is->audioq.serial);
    init_clock(&is->extclk, &is->extclk.serial);
    is->audio_clock_serial = -1;
    if (ffp->startup_volume < 0)
        av_log(NULL, AV_LOG_WARNING, "-volume=%d < 0, setting to 0\n", ffp->startup_volume);
    if (ffp->startup_volume > 100)
        av_log(NULL, AV_LOG_WARNING, "-volume=%d > 100, setting to 100\n", ffp->startup_volume);
    ffp->startup_volume = av_clip(ffp->startup_volume, 0, 100);
    ffp->startup_volume = av_clip(SDL_MIX_MAXVOLUME * ffp->startup_volume / 100, 0, SDL_MIX_MAXVOLUME);
    is->audio_volume = ffp->startup_volume;
    is->muted = 0;
    is->av_sync_type = ffp->av_sync_type;

    is->play_mutex = SDL_CreateMutex();
    is->accurate_seek_mutex = SDL_CreateMutex();
    ffp->is = is;
    is->pause_req = !ffp->start_on_prepared;

    is->video_refresh_tid = SDL_CreateThreadEx(&is->_video_refresh_tid, video_refresh_thread, ffp, "ff_vout");
    if (!is->video_refresh_tid) {
        av_freep(&ffp->is);
        return NULL;
    }

    is->read_tid = SDL_CreateThreadEx(&is->_read_tid, read_thread, ffp, "ff_read");
    if (!is->read_tid) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateThread(): %s\n", SDL_GetError());
fail:
        is->abort_request = true;
        if (is->video_refresh_tid)
            SDL_WaitThread(is->video_refresh_tid, NULL);
        stream_close(ffp);
        return NULL;
    }
    return is;
}

這里可以看到有3個(gè)隊(duì)列初始化城侧，分別是視頻、音頻和字幕况增，這些隊(duì)列通過frame_queue_init又分別分為2個(gè)隊(duì)列赞庶，原始的和解碼后的。再往下看就是2個(gè)線程的創(chuàng)建澳骤，分別是video_refresh_thread和read_thread歧强，從字面上理解，應(yīng)當(dāng)是輸出刷新視頻和讀取線程为肮。我們下面先從讀取線程入手摊册，整個(gè)代碼很長，注意這里的ic變量颊艳。是個(gè)AVFormatContext類型茅特，這里放的是流的信息和數(shù)據(jù)。

read_thread：

......
ic = avformat_alloc_context();
......
err = avformat_open_input(&ic, is->filename, is->iformat, &ffp->format_opts);
......
err = avformat_find_stream_info(ic, opts);
......
for (i = 0; i < ic->nb_streams; i++) {
        AVStream *st = ic->streams[i];
        enum AVMediaType type = st->codecpar->codec_type;
        st->discard = AVDISCARD_ALL;
        if (type >= 0 && ffp->wanted_stream_spec[type] && st_index[type] == -1)
            if (avformat_match_stream_specifier(ic, st, ffp->wanted_stream_spec[type]) > 0)
                st_index[type] = i;

        // choose first h264

        if (type == AVMEDIA_TYPE_VIDEO) {
            enum AVCodecID codec_id = st->codecpar->codec_id;
            video_stream_count++;
            if (codec_id == AV_CODEC_ID_H264) {
                h264_stream_count++;
                if (first_h264_stream < 0)
                    first_h264_stream = i;
            }
        }
    }
......
 /* open the streams */
    if (st_index[AVMEDIA_TYPE_AUDIO] >= 0) {
        stream_component_open(ffp, st_index[AVMEDIA_TYPE_AUDIO]);
    }

    ret = -1;
    if (st_index[AVMEDIA_TYPE_VIDEO] >= 0) {
        ret = stream_component_open(ffp, st_index[AVMEDIA_TYPE_VIDEO]);
    }
    if (is->show_mode == SHOW_MODE_NONE)
        is->show_mode = ret >= 0 ? SHOW_MODE_VIDEO : SHOW_MODE_RDFT;

    if (st_index[AVMEDIA_TYPE_SUBTITLE] >= 0) {
        stream_component_open(ffp, st_index[AVMEDIA_TYPE_SUBTITLE]);
    }
......
    /* offset should be seeked*/
    if (ffp->seek_at_start > 0) {
        ffp_seek_to_l(ffp, ffp->seek_at_start);
    }

    for (;;) {
        ......
        ret = av_read_frame(ic, pkt);
        ......
        /* check if packet is in play range specified by user, then queue, otherwise discard */
        stream_start_time = ic->streams[pkt->stream_index]->start_time;
        pkt_ts = pkt->pts == AV_NOPTS_VALUE ? pkt->dts : pkt->pts;
        pkt_in_play_range = ffp->duration == AV_NOPTS_VALUE ||
                (pkt_ts - (stream_start_time != AV_NOPTS_VALUE ? stream_start_time : 0)) *
                av_q2d(ic->streams[pkt->stream_index]->time_base) -
                (double)(ffp->start_time != AV_NOPTS_VALUE ? ffp->start_time : 0) / 1000000
                <= ((double)ffp->duration / 1000000);
         ......@@@
         if (pkt->stream_index == is->audio_stream && pkt_in_play_range) {
            packet_queue_put(&is->audioq, pkt);
        } else if (pkt->stream_index == is->video_stream && pkt_in_play_range
                   && !(is->video_st && (is->video_st->disposition & AV_DISPOSITION_ATTACHED_PIC))) {
            packet_queue_put(&is->videoq, pkt);
        } else if (pkt->stream_index == is->subtitle_stream && pkt_in_play_range) {
            packet_queue_put(&is->subtitleq, pkt);
        } else {
            av_packet_unref(pkt);
        }
    }
    ......

avformat_alloc_context是分配空間初始化棋枕。然后在avformat_open_input里面填充ic白修，這個(gè)函數(shù)里要讀取網(wǎng)絡(luò)數(shù)據(jù)包的信息，并判定格式等等操作重斑。這個(gè)for循環(huán)取出每一幀兵睛，然后進(jìn)行判斷類型，音視頻字幕歸類窥浪，并分別設(shè)置個(gè)數(shù)祖很。再來進(jìn)入到核心的一個(gè)函數(shù)，就是stream_component_open漾脂，這里根據(jù)不同類型的幀是否有來進(jìn)行流的讀取及解碼工作假颇。真正的讀取在av_read_frame，讀取解碼后的數(shù)據(jù)骨稿，讀取到pkt里笨鸡。這個(gè)過程是在一個(gè)for無限循環(huán)內(nèi)部進(jìn)行的姜钳，在seek的處理之后進(jìn)行。這個(gè)for不小心會(huì)漏看的......那么這個(gè)av_read_frame讀取到的是什么數(shù)據(jù)呢形耗？看結(jié)構(gòu)AVPacket傲须，這個(gè)的說明已經(jīng)挺清晰了，是一個(gè)壓縮的數(shù)據(jù)幀趟脂，是否是關(guān)鍵幀已經(jīng)在flags里標(biāo)記了泰讽。無論這個(gè)循環(huán)前后干了什么，都是要走這一步昔期，讀取數(shù)據(jù)幀已卸。下面有一大段是對錯(cuò)誤的處理，暫時(shí)略過硼一。下面有一段檢查數(shù)據(jù)包是否在用戶指定的播放范圍內(nèi)累澡，并根據(jù)時(shí)間戳排隊(duì)，否則丟棄的過程般贼。從stream_start_time=...開始愧哟，我理解的是計(jì)算出當(dāng)前數(shù)據(jù)幀的時(shí)間戳后再計(jì)算出播放的起始時(shí)間到當(dāng)前時(shí)間，然后看這個(gè)時(shí)間戳是否在此范圍內(nèi)哼蛆。范圍內(nèi)的就put到隊(duì)列中蕊梧，否則丟棄。

三腮介、流程圖

ijkplayer流程.png