ffplay.c

F:图像处理资料264264书籍ffmpeg-0.4.9-pre1VideoStream.rar 一个视频解压缩源代码

        int wanted_size, min_size, max_size, nb_samples;
            
        ref_clock = get_master_clock(is);
        diff = get_audio_clock(is) - ref_clock;
        
        if (diff < AV_NOSYNC_THRESHOLD) {
            is->audio_diff_cum = diff + is->audio_diff_avg_coef * is->audio_diff_cum;
            if (is->audio_diff_avg_count < AUDIO_DIFF_AVG_NB) {
                /* not enough measures to have a correct estimate */
                is->audio_diff_avg_count++;
            } else {
                /* estimate the A-V difference */
                avg_diff = is->audio_diff_cum * (1.0 - is->audio_diff_avg_coef);

                if (fabs(avg_diff) >= is->audio_diff_threshold) {
                    wanted_size = samples_size + ((int)(diff * is->audio_st->codec.sample_rate) * n);
                    nb_samples = samples_size / n;
                
                    min_size = ((nb_samples * (100 - SAMPLE_CORRECTION_PERCENT_MAX)) / 100) * n;
                    max_size = ((nb_samples * (100 + SAMPLE_CORRECTION_PERCENT_MAX)) / 100) * n;
                    if (wanted_size < min_size)
                        wanted_size = min_size;
                    else if (wanted_size > max_size)
                        wanted_size = max_size;
                    
                    /* add or remove samples to correction the synchro */
                    if (wanted_size < samples_size) {
                        /* remove samples */
                        samples_size = wanted_size;
                    } else if (wanted_size > samples_size) {
                        uint8_t *samples_end, *q;
                        int nb;
                        
                        /* add samples */
                        nb = (samples_size - wanted_size);
                        samples_end = (uint8_t *)samples + samples_size - n;
                        q = samples_end + n;
                        while (nb > 0) {
                            memcpy(q, samples_end, n);
                            q += n;
                            nb -= n;
                        }
                        samples_size = wanted_size;
                    }
                }
#if 0
                printf("diff=%f adiff=%f sample_diff=%d apts=%0.3f vpts=%0.3f %f\n", 
                       diff, avg_diff, samples_size - samples_size1, 
                       is->audio_clock, is->video_clock, is->audio_diff_threshold);
#endif
            }
        } else {
            /* too big difference : may be initial PTS errors, so
               reset A-V filter */
            is->audio_diff_avg_count = 0;
            is->audio_diff_cum = 0;
        }
    }

    return samples_size;
}

/* decode one audio frame and returns its uncompressed size */
static int audio_decode_frame(VideoState *is, uint8_t *audio_buf, double *pts_ptr)
{
    AVPacket *pkt = &is->audio_pkt;
    int n, len1, data_size;
    double pts;

    for(;;) {
        /* NOTE: the audio packet can contain several frames */
        while (is->audio_pkt_size > 0) {
            len1 = avcodec_decode_audio(&is->audio_st->codec, 
                                        (int16_t *)audio_buf, &data_size, 
                                        is->audio_pkt_data, is->audio_pkt_size);
            if (len1 < 0) {
                /* if error, we skip the frame */
                is->audio_pkt_size = 0;
                break;
            }
            
            is->audio_pkt_data += len1;
            is->audio_pkt_size -= len1;
            if (data_size <= 0)
                continue;
            /* if no pts, then compute it */
            pts = is->audio_clock;
            *pts_ptr = pts;
            n = 2 * is->audio_st->codec.channels;
            is->audio_clock += (double)data_size / 
                (double)(n * is->audio_st->codec.sample_rate);
#if defined(DEBUG_SYNC)
            {
                static double last_clock;
                printf("audio: delay=%0.3f clock=%0.3f pts=%0.3f\n",
                       is->audio_clock - last_clock,
                       is->audio_clock, pts);
                last_clock = is->audio_clock;
            }
#endif
            return data_size;
        }

        /* free the current packet */
        if (pkt->data)
            av_free_packet(pkt);
        
        if (is->paused || is->audioq.abort_request) {
            return -1;
        }
        
        /* read next packet */
        if (packet_queue_get(&is->audioq, pkt, 1) < 0)
            return -1;
        is->audio_pkt_data = pkt->data;
        is->audio_pkt_size = pkt->size;
        
        /* if update the audio clock with the pts */
        if (pkt->pts != AV_NOPTS_VALUE) {
            is->audio_clock = (double)pkt->pts / AV_TIME_BASE;
        }
    }
}

/* get the current audio output buffer size, in samples. With SDL, we
   cannot have a precise information */
static int audio_write_get_buf_size(VideoState *is)
{
    return is->audio_hw_buf_size - is->audio_buf_index;
}


/* prepare a new audio buffer */
void sdl_audio_callback(void *opaque, Uint8 *stream, int len)
{
    VideoState *is = opaque;
    int audio_size, len1;
    double pts;

    audio_callback_time = av_gettime();
    
    while (len > 0) {
        if (is->audio_buf_index >= is->audio_buf_size) {
           audio_size = audio_decode_frame(is, is->audio_buf, &pts);
           if (audio_size < 0) {
                /* if error, just output silence */
               is->audio_buf_size = 1024;
               memset(is->audio_buf, 0, is->audio_buf_size);
           } else {
               if (is->show_audio)
                   update_sample_display(is, (int16_t *)is->audio_buf, audio_size);
               audio_size = synchronize_audio(is, (int16_t *)is->audio_buf, audio_size, 
                                              pts);
               is->audio_buf_size = audio_size;
           }
           is->audio_buf_index = 0;
        }
        len1 = is->audio_buf_size - is->audio_buf_index;
        if (len1 > len)
            len1 = len;
        memcpy(stream, (uint8_t *)is->audio_buf + is->audio_buf_index, len1);
        len -= len1;
        stream += len1;
        is->audio_buf_index += len1;
    }
}


/* open a given stream. Return 0 if OK */
static int stream_component_open(VideoState *is, int stream_index)
{
    AVFormatContext *ic = is->ic;
    AVCodecContext *enc;
    AVCodec *codec;
    SDL_AudioSpec wanted_spec, spec;

    if (stream_index < 0 || stream_index >= ic->nb_streams)
        return -1;
    enc = &ic->streams[stream_index]->codec;
    
    /* prepare audio output */
    if (enc->codec_type == CODEC_TYPE_AUDIO) {
        wanted_spec.freq = enc->sample_rate;
        wanted_spec.format = AUDIO_S16SYS;
        /* hack for AC3. XXX: suppress that */
        if (enc->channels > 2)
            enc->channels = 2;
        wanted_spec.channels = enc->channels;
        wanted_spec.silence = 0;
        wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
        wanted_spec.callback = sdl_audio_callback;
        wanted_spec.userdata = is;
        if (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
            fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
            return -1;
        }
        is->audio_hw_buf_size = spec.size;
    }

    codec = avcodec_find_decoder(enc->codec_id);
    enc->debug_mv = debug_mv;
    enc->debug = debug;
    enc->workaround_bugs = workaround_bugs;
    if (!codec ||
        avcodec_open(enc, codec) < 0)
        return -1;
#if defined(HAVE_PTHREADS) || defined(HAVE_W32THREADS)
    if(thread_count>1)
        avcodec_thread_init(enc, thread_count);
#endif
    enc->thread_count= thread_count;
    switch(enc->codec_type) {
    case CODEC_TYPE_AUDIO:
        is->audio_stream = stream_index;
        is->audio_st = ic->streams[stream_index];
        is->audio_buf_size = 0;
        is->audio_buf_index = 0;

        /* init averaging filter */
        is->audio_diff_avg_coef = exp(log(0.01) / AUDIO_DIFF_AVG_NB);
        is->audio_diff_avg_count = 0;
        /* since we do not have a precise anough audio fifo fullness,
           we correct audio sync only if larger than this threshold */
        is->audio_diff_threshold = 2.0 * SDL_AUDIO_BUFFER_SIZE / enc->sample_rate;

        memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));
        packet_queue_init(&is->audioq);
	SDL_PauseAudio(0);
        break;
    case CODEC_TYPE_VIDEO:
        is->video_stream = stream_index;
        is->video_st = ic->streams[stream_index];

        is->frame_last_delay = 40e-3;
        is->frame_timer = (double)av_gettime() / 1000000.0;
        is->video_current_pts_time = av_gettime();

        packet_queue_init(&is->videoq);
        is->video_tid = SDL_CreateThread(video_thread, is);
        break;
    default:
        break;
    }
    return 0;
}

static void stream_component_close(VideoState *is, int stream_index)
{
    AVFormatContext *ic = is->ic;
    AVCodecContext *enc;
    
    enc = &ic->streams[stream_index]->codec;

    switch(enc->codec_type) {
    case CODEC_TYPE_AUDIO:
        packet_queue_abort(&is->audioq);

        SDL_CloseAudio();

        packet_queue_end(&is->audioq);
        break;
    case CODEC_TYPE_VIDEO:
        packet_queue_abort(&is->videoq);

        /* note: we also signal this mutex to make sure we deblock the
           video thread in all cases */
        SDL_LockMutex(is->pictq_mutex);
        SDL_CondSignal(is->pictq_cond);
        SDL_UnlockMutex(is->pictq_mutex);

        SDL_WaitThread(is->video_tid, NULL);

        packet_queue_end(&is->videoq);
        break;
    default:
        break;
    }

    avcodec_close(enc);
    switch(enc->codec_type) {
    case CODEC_TYPE_AUDIO:
        is->audio_st = NULL;
        is->audio_stream = -1;
        break;
    case CODEC_TYPE_VIDEO:
        is->video_st = NULL;
        is->video_stream = -1;
        break;
    default:
        break;
    }
}

void dump_stream_info(AVFormatContext *s)
{
    if (s->track != 0)
        fprintf(stderr, "Track: %d\n", s->track);
    if (s->title[0] != '\0')
        fprintf(stderr, "Title: %s\n", s->title);
    if (s->author[0] != '\0')
        fprintf(stderr, "Author: %s\n", s->author);
    if (s->album[0] != '\0')
        fprintf(stderr, "Album: %s\n", s->album);
    if (s->year != 0)
        fprintf(stderr, "Year: %d\n", s->year);
    if (s->genre[0] != '\0')
        fprintf(stderr, "Genre: %s\n", s->genre);
}

/* since we have only one decoding thread, we can use a global
   variable instead of a thread local variable */
static VideoState *global_video_state;

static int decode_interrupt_cb(void)
{
    return (global_video_state && global_video_state->abort_request);
}

/* this thread gets the stream from the disk or the network */
static int decode_thread(void *arg)
{
    VideoState *is = arg;
    AVFormatContext *ic;
    int err, i, ret, video_index, audio_index, use_play;
    AVPacket pkt1, *pkt = &pkt1;
    AVFormatParameters params, *ap = &params;

    video_index = -1;
    audio_index = -1;
    is->video_stream = -1;
    is->audio_stream = -1;

    global_video_state = is;
    url_set_interrupt_cb(decode_interrupt_cb);

    memset(ap, 0, sizeof(*ap));
    ap->image_format = image_format;
    ap->initial_pause = 1; /* we force a pause when starting an RTSP
                              stream */
    
    err = av_open_input_file(&ic, is->filename, is->iformat, 0, ap);
    if (err < 0) {
        print_error(is->filename, err);
        ret = -1;
        goto fail;
    }
    is->ic = ic;
#ifdef CONFIG_NETWORK
    use_play = (ic->iformat == &rtsp_demux);
#else
    use_play = 0;
#endif
    if (!use_play) {
        err = av_find_stream_info(ic);
        if (err < 0) {
            fprintf(stderr, "%s: could not find codec parameters\n", is->filename);
            ret = -1;
            goto fail;
        }
    }

    /* if seeking requested, we execute it */
    if (start_time != AV_NOPTS_VALUE) {
        int64_t timestamp;

        timestamp = start_time;
        /* add the stream start time */
        if (ic->start_time != AV_NOPTS_VALUE)
            timestamp += ic->start_time;
        ret = av_seek_frame(ic, -1, timestamp);
        if (ret < 0) {
            fprintf(stderr, "%s: could not seek to position %0.3f\n", 
                    is->filename, (double)timestamp / AV_TIME_BASE);
        }
    }

    /* now we can begin to play (RTSP stream only) */
    av_read_play(ic);

    if (use_play) {
        err = av_find_stream_info(ic);
        if (err < 0) {
            fprintf(stderr, "%s: could not find codec parameters\n", is->filename);
            ret = -1;
            goto fail;
        }
    }

    for(i = 0; i < ic->nb_streams; i++) {
        AVCodecContext *enc = &ic->streams[i]->codec;
        switch(enc->codec_type) {
        case CODEC_TYPE_AUDIO:
            if (audio_index < 0 && !audio_disable)
                audio_index = i;
            break;
        case CODEC_TYPE_VIDEO:
            if (video_index < 0 && !video_disable)
                video_index = i;
            break;
        default:
            break;
        }
    }
    if (show_status) {
        dump_format(ic, 0, is->filename, 0);
        dump_stream_info(ic);
    }

    /* open the streams */
    if (audio_index >= 0) {
        stream_component_open(is, audio_index);
    }

    if (video_index >= 0) {
        stream_component_open(is, video_index);
    } else {
        if (!display_disable)
            is->show_audio = 1;
    }

    if (is->video_stream < 0 && is->audio_stream < 0) {
        fprintf(stderr, "%s: could not open codecs\n", is->filename);
        ret = -1;
        goto fail;
    }

    for(;;) {
        if (is->abort_request)
            break;
#ifdef CONFIG_NETWORK
        if (is->paused != is->last_paused) {
            is->last_paused = is->paused;
            if (is->paused)
                av_read_pause(ic);
            else
                av_read_play(ic);
        }
        if (is->paused && ic->iformat == &rtsp_demux) {
            /* wait 10 ms to avoid trying to get another packet */
            /* XXX: horrible */
            SDL_Delay(10);
            continue;
        }
#endif
        if (is->seek_req) {
            /* XXX: must lock decoder threads */
            ret = av_seek_frame(is->ic, -1, is->seek_pos);
            if (ret < 0) {
                fprintf(stderr, "%s: error while seeking\n", is->ic->filename);
            }else{
                if (is->audio_stream >= 0) {
                    packet_queue_flush(&is->audioq);
                }
                if (is->video_stream >= 0) {
                    packet_queue_flush(&is->videoq);
                    avcodec_flush_buffers(&ic->streams[video_index]->codec);
                }
            }
            is->seek_req = 0;
        }

        /* if the queue are full, no need to read more */
        if (is->audioq.size > MAX_AUDIOQ_SIZE ||
            is->videoq.size > MAX_VIDEOQ_SIZE || 
            url_feof(&ic->pb)) {
            /* wait 10 ms */
            SDL_Delay(10);
            continue;
        }
        ret = av_read_frame(ic, pkt);
        if (ret < 0) {
            break;
        }
        if (pkt->stream_index == is->audio_stream) {
            packet_queue_put(&is->audioq, pkt);
        } else if (pkt->stream_index == is->video_stream) {
            packet_queue_put(&is->videoq, pkt);
        } else {
            av_free_packet(pkt);
        }
    }
    /* wait until the end */
    while (!is->abort_request) {
        SDL_Delay(100);
    }