dvenc.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

                dv_write_pack(dv_timecode, c, &buf[j+k]);

            if (((long)(buf-frame)/(c->sys->frame_size/(c->sys->difseg_size*c->sys->n_difchan))%c->sys->difseg_size) > 5) { /* FIXME: is this really needed ? */
                dv_write_pack(dv_video_recdate, c, &buf[j+14]);
                dv_write_pack(dv_video_rectime, c, &buf[j+22]);
                dv_write_pack(dv_video_recdate, c, &buf[j+38]);
                dv_write_pack(dv_video_rectime, c, &buf[j+46]);
            }
        }

        /* DV VAUX: 4th, 5th and 6th 3DIFs */
        for (j = 80*3 + 3; j < 80*6; j += 80) {
            dv_write_pack(dv_video_recdate, c, &buf[j+5*2]);
            dv_write_pack(dv_video_rectime, c, &buf[j+5*3]);
            dv_write_pack(dv_video_recdate, c, &buf[j+5*11]);
            dv_write_pack(dv_video_rectime, c, &buf[j+5*12]);
        }
    }
}

/*
 * The following 3 functions constitute our interface to the world
 */

int dv_assemble_frame(DVMuxContext *c, AVStream* st,
                      const uint8_t* data, int data_size, uint8_t** frame)
{
    int i, reqasize;

    *frame = &c->frame_buf[0];
    reqasize = 4 * dv_audio_frame_size(c->sys, c->frames);

    switch (st->codec->codec_type) {
    case CODEC_TYPE_VIDEO:
        /* FIXME: we have to have more sensible approach than this one */
        if (c->has_video)
            av_log(st->codec, AV_LOG_ERROR, "Can't process DV frame #%d. Insufficient audio data or severe sync problem.\n", c->frames);

        memcpy(*frame, data, c->sys->frame_size);
        c->has_video = 1;
        break;
    case CODEC_TYPE_AUDIO:
        for (i = 0; i < c->n_ast && st != c->ast[i]; i++);

          /* FIXME: we have to have more sensible approach than this one */
        if (av_fifo_size(&c->audio_data[i]) + data_size >= 100*AVCODEC_MAX_AUDIO_FRAME_SIZE)
            av_log(st->codec, AV_LOG_ERROR, "Can't process DV frame #%d. Insufficient video data or severe sync problem.\n", c->frames);
        av_fifo_write(&c->audio_data[i], data, data_size);

        /* Lets see if we've got enough audio for one DV frame */
        c->has_audio |= ((reqasize <= av_fifo_size(&c->audio_data[i])) << i);

        break;
    default:
        break;
    }

    /* Lets see if we have enough data to construct one DV frame */
    if (c->has_video == 1 && c->has_audio + 1 == 1<<c->n_ast) {
        dv_inject_metadata(c, *frame);
        c->has_audio = 0;
        for (i=0; i<c->n_ast; i++) {
            dv_inject_audio(c, i, *frame);
            av_fifo_drain(&c->audio_data[i], reqasize);
            c->has_audio |= ((reqasize <= av_fifo_size(&c->audio_data[i])) << i);
        }

        c->has_video = 0;

        c->frames++;

        return c->sys->frame_size;
    }

    return 0;
}

DVMuxContext* dv_init_mux(AVFormatContext* s)
{
    DVMuxContext *c = s->priv_data;
    AVStream *vst = NULL;
    int i;

    /* we support at most 1 video and 2 audio streams */
    if (s->nb_streams > 3)
        return NULL;

    c->n_ast = 0;
    c->ast[0] = c->ast[1] = NULL;

    /* We have to sort out where audio and where video stream is */
    for (i=0; i<s->nb_streams; i++) {
        switch (s->streams[i]->codec->codec_type) {
        case CODEC_TYPE_VIDEO:
            if (vst) return NULL;
            vst = s->streams[i];
            break;
        case CODEC_TYPE_AUDIO:
            if (c->n_ast > 1) return NULL;
            c->ast[c->n_ast++] = s->streams[i];
            break;
        default:
            goto bail_out;
        }
    }

    /* Some checks -- DV format is very picky about its incoming streams */
    if (!vst || vst->codec->codec_id != CODEC_ID_DVVIDEO)
        goto bail_out;
    for (i=0; i<c->n_ast; i++) {
        if (c->ast[i] && (c->ast[i]->codec->codec_id != CODEC_ID_PCM_S16LE ||
                          c->ast[i]->codec->sample_rate != 48000 ||
                          c->ast[i]->codec->channels != 2))
            goto bail_out;
    }
    c->sys = dv_codec_profile(vst->codec);
    if (!c->sys)
        goto bail_out;

    if((c->n_ast > 1) && (c->sys->n_difchan < 2)) {
        /* only 1 stereo pair is allowed in 25Mbps mode */
        goto bail_out;
    }

    /* Ok, everything seems to be in working order */
    c->frames = 0;
    c->has_audio = 0;
    c->has_video = 0;
    c->start_time = (time_t)s->timestamp;

    for (i=0; i<c->n_ast; i++) {
        if (c->ast[i] && av_fifo_init(&c->audio_data[i], 100*AVCODEC_MAX_AUDIO_FRAME_SIZE) < 0) {
            while (i>0) {
                i--;
                av_fifo_free(&c->audio_data[i]);
            }
            goto bail_out;
        }
    }

    return c;

bail_out:
    return NULL;
}

void dv_delete_mux(DVMuxContext *c)
{
    int i;
    for (i=0; i < c->n_ast; i++)
        av_fifo_free(&c->audio_data[i]);
}

#ifdef CONFIG_MUXERS
static int dv_write_header(AVFormatContext *s)
{
    if (!dv_init_mux(s)) {
        av_log(s, AV_LOG_ERROR, "Can't initialize DV format!\n"
                    "Make sure that you supply exactly two streams:\n"
                    "     video: 25fps or 29.97fps, audio: 2ch/48Khz/PCM\n"
                    "     (50Mbps allows an optional second audio stream)\n");
        return -1;
    }
    return 0;
}

static int dv_write_packet(struct AVFormatContext *s, AVPacket *pkt)
{
    uint8_t* frame;
    int fsize;

    fsize = dv_assemble_frame(s->priv_data, s->streams[pkt->stream_index],
                              pkt->data, pkt->size, &frame);
    if (fsize > 0) {
        put_buffer(&s->pb, frame, fsize);
        put_flush_packet(&s->pb);
    }
    return 0;
}

/*
 * We might end up with some extra A/V data without matching counterpart.
 * E.g. video data without enough audio to write the complete frame.
 * Currently we simply drop the last frame. I don't know whether this
 * is the best strategy of all
 */
static int dv_write_trailer(struct AVFormatContext *s)
{
    dv_delete_mux(s->priv_data);
    return 0;
}
#endif /* CONFIG_MUXERS */

#ifdef CONFIG_DV_MUXER
AVOutputFormat dv_muxer = {
    "dv",
    "DV video format",
    NULL,
    "dv",
    sizeof(DVMuxContext),
    CODEC_ID_PCM_S16LE,
    CODEC_ID_DVVIDEO,
    dv_write_header,
    dv_write_packet,
    dv_write_trailer,
};
#endif