ffplay.c

ffmpeg源码分析

{
    double delta;
    if (is->paused) {
        delta = 0;
    } else {
        delta = (av_gettime() - is->video_current_pts_time) / 1000000.0;
    }
    return is->video_current_pts + delta;
}

/* get the current external clock value */
static double get_external_clock(VideoState *is)
{
    int64_t ti;
    ti = av_gettime();
    return is->external_clock + ((ti - is->external_clock_time) * 1e-6);
}

/* get the current master clock value */
static double get_master_clock(VideoState *is)
{
    double val;

    if (is->av_sync_type == AV_SYNC_VIDEO_MASTER) {
        if (is->video_st)
            val = get_video_clock(is);
        else
            val = get_audio_clock(is);
    } else if (is->av_sync_type == AV_SYNC_AUDIO_MASTER) {
        if (is->audio_st)
            val = get_audio_clock(is);
        else
            val = get_video_clock(is);
    } else {
        val = get_external_clock(is);
    }
    return val;
}

/* seek in the stream */
static void stream_seek(VideoState *is, int64_t pos, int rel)
{
    if (!is->seek_req) {
        is->seek_pos = pos;
        is->seek_flags = rel < 0 ? AVSEEK_FLAG_BACKWARD : 0;
        is->seek_req = 1;
    }
}

/* pause or resume the video */
static void stream_pause(VideoState *is)
{
    is->paused = !is->paused;
    if (is->paused) {
        is->video_current_pts = get_video_clock(is);
    }
}

/* called to display each frame */
static void video_refresh_timer(void *opaque)
{
    VideoState *is = opaque;
    VideoPicture *vp;
    double actual_delay, delay, sync_threshold, ref_clock, diff;

    SubPicture *sp, *sp2;

    if (is->video_st) {
        if (is->pictq_size == 0) {
            /* if no picture, need to wait */
            schedule_refresh(is, 1);
        } else {
            /* dequeue the picture */
            vp = &is->pictq[is->pictq_rindex];

            /* update current video pts */
            is->video_current_pts = vp->pts;
            is->video_current_pts_time = av_gettime();

            /* compute nominal delay */
            delay = vp->pts - is->frame_last_pts;
            if (delay <= 0 || delay >= 1.0) {
                /* if incorrect delay, use previous one */
                delay = is->frame_last_delay;
            }
            is->frame_last_delay = delay;
            is->frame_last_pts = vp->pts;

            /* update delay to follow master synchronisation source */
            if (((is->av_sync_type == AV_SYNC_AUDIO_MASTER && is->audio_st) ||
                 is->av_sync_type == AV_SYNC_EXTERNAL_CLOCK)) {
                /* if video is slave, we try to correct big delays by
                   duplicating or deleting a frame */
                ref_clock = get_master_clock(is);
                diff = vp->pts - ref_clock;

                /* skip or repeat frame. We take into account the
                   delay to compute the threshold. I still don't know
                   if it is the best guess */
                sync_threshold = AV_SYNC_THRESHOLD;
                if (delay > sync_threshold)
                    sync_threshold = delay;
                if (fabs(diff) < AV_NOSYNC_THRESHOLD) {
                    if (diff <= -sync_threshold)
                        delay = 0;
                    else if (diff >= sync_threshold)
                        delay = 2 * delay;
                }
            }

            is->frame_timer += delay;
            /* compute the REAL delay (we need to do that to avoid
               long term errors */
            actual_delay = is->frame_timer - (av_gettime() / 1000000.0);
            if (actual_delay < 0.010) {
                /* XXX: should skip picture */
                actual_delay = 0.010;
            }
            /* launch timer for next picture */
            schedule_refresh(is, (int)(actual_delay * 1000 + 0.5));

#if defined(DEBUG_SYNC)
            printf("video: delay=%0.3f actual_delay=%0.3f pts=%0.3f A-V=%f\n",
                   delay, actual_delay, vp->pts, -diff);
#endif

            if(is->subtitle_st) {
                if (is->subtitle_stream_changed) {
                    SDL_LockMutex(is->subpq_mutex);

                    while (is->subpq_size) {
                        free_subpicture(&is->subpq[is->subpq_rindex]);

                        /* update queue size and signal for next picture */
                        if (++is->subpq_rindex == SUBPICTURE_QUEUE_SIZE)
                            is->subpq_rindex = 0;

                        is->subpq_size--;
                    }
                    is->subtitle_stream_changed = 0;

                    SDL_CondSignal(is->subpq_cond);
                    SDL_UnlockMutex(is->subpq_mutex);
                } else {
                    if (is->subpq_size > 0) {
                        sp = &is->subpq[is->subpq_rindex];

                        if (is->subpq_size > 1)
                            sp2 = &is->subpq[(is->subpq_rindex + 1) % SUBPICTURE_QUEUE_SIZE];
                        else
                            sp2 = NULL;

                        if ((is->video_current_pts > (sp->pts + ((float) sp->sub.end_display_time / 1000)))
                                || (sp2 && is->video_current_pts > (sp2->pts + ((float) sp2->sub.start_display_time / 1000))))
                        {
                            free_subpicture(sp);

                            /* update queue size and signal for next picture */
                            if (++is->subpq_rindex == SUBPICTURE_QUEUE_SIZE)
                                is->subpq_rindex = 0;

                            SDL_LockMutex(is->subpq_mutex);
                            is->subpq_size--;
                            SDL_CondSignal(is->subpq_cond);
                            SDL_UnlockMutex(is->subpq_mutex);
                        }
                    }
                }
            }

            /* display picture */
            video_display(is);

            /* update queue size and signal for next picture */
            if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE)
                is->pictq_rindex = 0;

            SDL_LockMutex(is->pictq_mutex);
            is->pictq_size--;
            SDL_CondSignal(is->pictq_cond);
            SDL_UnlockMutex(is->pictq_mutex);
        }
    } else if (is->audio_st) {
        /* draw the next audio frame */

        schedule_refresh(is, 40);

        /* if only audio stream, then display the audio bars (better
           than nothing, just to test the implementation */

        /* display picture */
        video_display(is);
    } else {
        schedule_refresh(is, 100);
    }
    if (show_status) {
        static int64_t last_time;
        int64_t cur_time;
        int aqsize, vqsize, sqsize;
        double av_diff;

        cur_time = av_gettime();
        if (!last_time || (cur_time - last_time) >= 500 * 1000) {
            aqsize = 0;
            vqsize = 0;
            sqsize = 0;
            if (is->audio_st)
                aqsize = is->audioq.size;
            if (is->video_st)
                vqsize = is->videoq.size;
            if (is->subtitle_st)
                sqsize = is->subtitleq.size;
            av_diff = 0;
            if (is->audio_st && is->video_st)
                av_diff = get_audio_clock(is) - get_video_clock(is);
            printf("%7.2f A-V:%7.3f aq=%5dKB vq=%5dKB sq=%5dB    \r",
                   get_master_clock(is), av_diff, aqsize / 1024, vqsize / 1024, sqsize);
            fflush(stdout);
            last_time = cur_time;
        }
    }
}

/* allocate a picture (needs to do that in main thread to avoid
   potential locking problems */
static void alloc_picture(void *opaque)
{
    VideoState *is = opaque;
    VideoPicture *vp;

    vp = &is->pictq[is->pictq_windex];

    if (vp->bmp)
        SDL_FreeYUVOverlay(vp->bmp);

#if 0
    /* XXX: use generic function */
    /* XXX: disable overlay if no hardware acceleration or if RGB format */
    switch(is->video_st->codec->pix_fmt) {
    case PIX_FMT_YUV420P:
    case PIX_FMT_YUV422P:
    case PIX_FMT_YUV444P:
    case PIX_FMT_YUV422:
    case PIX_FMT_YUV410P:
    case PIX_FMT_YUV411P:
        is_yuv = 1;
        break;
    default:
        is_yuv = 0;
        break;
    }
#endif
    vp->bmp = SDL_CreateYUVOverlay(is->video_st->codec->width,
                                   is->video_st->codec->height,
                                   SDL_YV12_OVERLAY,
                                   screen);
    vp->width = is->video_st->codec->width;
    vp->height = is->video_st->codec->height;

    SDL_LockMutex(is->pictq_mutex);
    vp->allocated = 1;
    SDL_CondSignal(is->pictq_cond);
    SDL_UnlockMutex(is->pictq_mutex);
}

/**
 *
 * @param pts the dts of the pkt / pts of the frame and guessed if not known
 */
static int queue_picture(VideoState *is, AVFrame *src_frame, double pts)
{
    VideoPicture *vp;
    int dst_pix_fmt;
    AVPicture pict;

    /* wait until we have space to put a new picture */
    SDL_LockMutex(is->pictq_mutex);
    while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE &&
           !is->videoq.abort_request) {
        SDL_CondWait(is->pictq_cond, is->pictq_mutex);
    }
    SDL_UnlockMutex(is->pictq_mutex);

    if (is->videoq.abort_request)
        return -1;

    vp = &is->pictq[is->pictq_windex];

    /* alloc or resize hardware picture buffer */
    if (!vp->bmp ||
        vp->width != is->video_st->codec->width ||
        vp->height != is->video_st->codec->height) {
        SDL_Event event;

        vp->allocated = 0;

        /* the allocation must be done in the main thread to avoid
           locking problems */
        event.type = FF_ALLOC_EVENT;
        event.user.data1 = is;
        SDL_PushEvent(&event);

        /* wait until the picture is allocated */
        SDL_LockMutex(is->pictq_mutex);
        while (!vp->allocated && !is->videoq.abort_request) {
            SDL_CondWait(is->pictq_cond, is->pictq_mutex);
        }
        SDL_UnlockMutex(is->pictq_mutex);

        if (is->videoq.abort_request)
            return -1;
    }

    /* if the frame is not skipped, then display it */
    if (vp->bmp) {
        /* get a pointer on the bitmap */
        SDL_LockYUVOverlay (vp->bmp);

        dst_pix_fmt = PIX_FMT_YUV420P;
        pict.data[0] = vp->bmp->pixels[0];
        pict.data[1] = vp->bmp->pixels[2];
        pict.data[2] = vp->bmp->pixels[1];

        pict.linesize[0] = vp->bmp->pitches[0];
        pict.linesize[1] = vp->bmp->pitches[2];
        pict.linesize[2] = vp->bmp->pitches[1];
        img_convert(&pict, dst_pix_fmt,
                    (AVPicture *)src_frame, is->video_st->codec->pix_fmt,
                    is->video_st->codec->width, is->video_st->codec->height);
        /* update the bitmap content */
        SDL_UnlockYUVOverlay(vp->bmp);

        vp->pts = pts;

        /* now we can update the picture count */
        if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE)
            is->pictq_windex = 0;
        SDL_LockMutex(is->pictq_mutex);
        is->pictq_size++;
        SDL_UnlockMutex(is->pictq_mutex);
    }
    return 0;
}

/**
 * compute the exact PTS for the picture if it is omitted in the stream
 * @param pts1 the dts of the pkt / pts of the frame
 */
static int output_picture2(VideoState *is, AVFrame *src_frame, double pts1)
{
    double frame_delay, pts;

    pts = pts1;

    if (pts != 0) {
        /* update video clock with pts, if present */
        is->video_clock = pts;
    } else {
        pts = is->video_clock;
    }
    /* update video clock for next frame */
    frame_delay = av_q2d(is->video_st->codec->time_base);
    /* for MPEG2, the frame can be repeated, so we update the
       clock accordingly */
    frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
    is->video_clock += frame_delay;

#if defined(DEBUG_SYNC) && 0
    {
        int ftype;
        if (src_frame->pict_type == FF_B_TYPE)
            ftype = 'B';
        else if (src_frame->pict_type == FF_I_TYPE)
            ftype = 'I';
        else
            ftype = 'P';
        printf("frame_type=%c clock=%0.3f pts=%0.3f\n",
               ftype, pts, pts1);
    }
#endif
    return queue_picture(is, src_frame, pts);
}

static int video_thread(void *arg)
{
    VideoState *is = arg;
    AVPacket pkt1, *pkt = &pkt1;
    int len1, got_picture;
    AVFrame *frame= avcodec_alloc_frame();
    double pts;

    for(;;) {
        while (is->paused && !is->videoq.abort_request) {
            SDL_Delay(10);
        }
        if (packet_queue_get(&is->videoq, pkt, 1) < 0)
            break;
        /* NOTE: ipts is the PTS of the _first_ picture beginning in
           this packet, if any */
        pts = 0;
        if (pkt->dts != AV_NOPTS_VALUE)
            pts = av_q2d(is->video_st->time_base)*pkt->dts;

            SDL_LockMutex(is->video_decoder_mutex);
            len1 = avcodec_decode_video(is->video_st->codec,
                                        frame, &got_picture,
                                        pkt->data, pkt->size);
            SDL_UnlockMutex(is->video_decoder_mutex);
//            if (len1 < 0)
//                break;
            if (got_picture) {
                if (output_picture2(is, frame, pts) < 0)
                    goto the_end;
            }
        av_free_packet(pkt);
        if (step)
            if (cur_stream)
                stream_pause(cur_stream);
    }
 the_end:
    av_free(frame);
    return 0;
}

static int subtitle_thread(void *arg)
{
    VideoState *is = arg;
    SubPicture *sp;
    AVPacket pkt1, *pkt = &pkt1;
    int len1, got_subtitle;
    double pts;
    int i, j;
    int r, g, b, y, u, v, a;

    for(;;) {
        while (is->paused && !is->subtitleq.abort_request) {
            SDL_Delay(10);
        }
        if (packet_queue_get(&is->subtitleq, pkt, 1) < 0)