ipmovie.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

            break;

        case OPCODE_CREATE_TIMER:
            debug_ipmovie("create timer\n");
            if ((opcode_version > 0) || (opcode_size > 6)) {
                debug_ipmovie("bad create_timer opcode\n");
                chunk_type = CHUNK_BAD;
                break;
            }
            if (get_buffer(pb, scratch, opcode_size) !=
                opcode_size) {
                chunk_type = CHUNK_BAD;
                break;
            }
            s->fps = 1000000.0 / (AV_RL32(&scratch[0]) * AV_RL16(&scratch[4]));
            s->frame_pts_inc = 90000 / s->fps;
            debug_ipmovie("  %.2f frames/second (timer div = %d, subdiv = %d)\n",
                s->fps, AV_RL32(&scratch[0]), AV_RL16(&scratch[4]));
            break;

        case OPCODE_INIT_AUDIO_BUFFERS:
            debug_ipmovie("initialize audio buffers\n");
            if ((opcode_version > 1) || (opcode_size > 10)) {
                debug_ipmovie("bad init_audio_buffers opcode\n");
                chunk_type = CHUNK_BAD;
                break;
            }
            if (get_buffer(pb, scratch, opcode_size) !=
                opcode_size) {
                chunk_type = CHUNK_BAD;
                break;
            }
            s->audio_sample_rate = AV_RL16(&scratch[4]);
            audio_flags = AV_RL16(&scratch[2]);
            /* bit 0 of the flags: 0 = mono, 1 = stereo */
            s->audio_channels = (audio_flags & 1) + 1;
            /* bit 1 of the flags: 0 = 8 bit, 1 = 16 bit */
            s->audio_bits = (((audio_flags >> 1) & 1) + 1) * 8;
            /* bit 2 indicates compressed audio in version 1 opcode */
            if ((opcode_version == 1) && (audio_flags & 0x4))
                s->audio_type = CODEC_ID_INTERPLAY_DPCM;
            else if (s->audio_bits == 16)
                s->audio_type = CODEC_ID_PCM_S16LE;
            else
                s->audio_type = CODEC_ID_PCM_U8;
            debug_ipmovie("audio: %d bits, %d Hz, %s, %s format\n",
                s->audio_bits,
                s->audio_sample_rate,
                (s->audio_channels == 2) ? "stereo" : "mono",
                (s->audio_type == CODEC_ID_INTERPLAY_DPCM) ?
                "Interplay audio" : "PCM");
            break;

        case OPCODE_START_STOP_AUDIO:
            debug_ipmovie("start/stop audio\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_INIT_VIDEO_BUFFERS:
            debug_ipmovie("initialize video buffers\n");
            if ((opcode_version > 2) || (opcode_size > 8)) {
                debug_ipmovie("bad init_video_buffers opcode\n");
                chunk_type = CHUNK_BAD;
                break;
            }
            if (get_buffer(pb, scratch, opcode_size) !=
                opcode_size) {
                chunk_type = CHUNK_BAD;
                break;
            }
            s->video_width = AV_RL16(&scratch[0]) * 8;
            s->video_height = AV_RL16(&scratch[2]) * 8;
            debug_ipmovie("video resolution: %d x %d\n",
                s->video_width, s->video_height);
            break;

        case OPCODE_UNKNOWN_06:
        case OPCODE_UNKNOWN_0E:
        case OPCODE_UNKNOWN_10:
        case OPCODE_UNKNOWN_12:
        case OPCODE_UNKNOWN_13:
        case OPCODE_UNKNOWN_14:
        case OPCODE_UNKNOWN_15:
            debug_ipmovie("unknown (but documented) opcode %02X\n", opcode_type);
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_SEND_BUFFER:
            debug_ipmovie("send buffer\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_AUDIO_FRAME:
            debug_ipmovie("audio frame\n");

            /* log position and move on for now */
            s->audio_chunk_offset = url_ftell(pb);
            s->audio_chunk_size = opcode_size;
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_SILENCE_FRAME:
            debug_ipmovie("silence frame\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_INIT_VIDEO_MODE:
            debug_ipmovie("initialize video mode\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_CREATE_GRADIENT:
            debug_ipmovie("create gradient\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_SET_PALETTE:
            debug_ipmovie("set palette\n");
            /* check for the logical maximum palette size
             * (3 * 256 + 4 bytes) */
            if (opcode_size > 0x304) {
                debug_ipmovie("demux_ipmovie: set_palette opcode too large\n");
                chunk_type = CHUNK_BAD;
                break;
            }
            if (get_buffer(pb, scratch, opcode_size) != opcode_size) {
                chunk_type = CHUNK_BAD;
                break;
            }

            /* load the palette into internal data structure */
            first_color = AV_RL16(&scratch[0]);
            last_color = first_color + AV_RL16(&scratch[2]) - 1;
            /* sanity check (since they are 16 bit values) */
            if ((first_color > 0xFF) || (last_color > 0xFF)) {
                debug_ipmovie("demux_ipmovie: set_palette indices out of range (%d -> %d)\n",
                    first_color, last_color);
                chunk_type = CHUNK_BAD;
                break;
            }
            j = 4;  /* offset of first palette data */
            for (i = first_color; i <= last_color; i++) {
                /* the palette is stored as a 6-bit VGA palette, thus each
                 * component is shifted up to a 8-bit range */
                r = scratch[j++] * 4;
                g = scratch[j++] * 4;
                b = scratch[j++] * 4;
                s->palette_control.palette[i] = (r << 16) | (g << 8) | (b);
            }
            /* indicate a palette change */
            s->palette_control.palette_changed = 1;
            break;

        case OPCODE_SET_PALETTE_COMPRESSED:
            debug_ipmovie("set palette compressed\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_SET_DECODING_MAP:
            debug_ipmovie("set decoding map\n");

            /* log position and move on for now */
            s->decode_map_chunk_offset = url_ftell(pb);
            s->decode_map_chunk_size = opcode_size;
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_VIDEO_DATA:
            debug_ipmovie("set video data\n");

            /* log position and move on for now */
            s->video_chunk_offset = url_ftell(pb);
            s->video_chunk_size = opcode_size;
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        default:
            debug_ipmovie("*** unknown opcode type\n");
            chunk_type = CHUNK_BAD;
            break;

        }
    }

    /* make a note of where the stream is sitting */
    s->next_chunk_offset = url_ftell(pb);

    /* dispatch the first of any pending packets */
    if ((chunk_type == CHUNK_VIDEO) || (chunk_type == CHUNK_AUDIO_ONLY))
        chunk_type = load_ipmovie_packet(s, pb, pkt);

    return chunk_type;
}

static int ipmovie_probe(AVProbeData *p)
{
    if (strncmp(p->buf, IPMOVIE_SIGNATURE, IPMOVIE_SIGNATURE_SIZE) != 0)
        return 0;

    return AVPROBE_SCORE_MAX;
}

static int ipmovie_read_header(AVFormatContext *s,
                               AVFormatParameters *ap)
{
    IPMVEContext *ipmovie = s->priv_data;
    ByteIOContext *pb = &s->pb;
    AVPacket pkt;
    AVStream *st;
    unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
    int chunk_type;

    /* initialize private context members */
    ipmovie->video_pts = ipmovie->audio_frame_count = 0;
    ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
    ipmovie->decode_map_chunk_offset = 0;

    /* on the first read, this will position the stream at the first chunk */
    ipmovie->next_chunk_offset = IPMOVIE_SIGNATURE_SIZE + 6;

    /* process the first chunk which should be CHUNK_INIT_VIDEO */
    if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_VIDEO)
        return AVERROR_INVALIDDATA;

    /* peek ahead to the next chunk-- if it is an init audio chunk, process
     * it; if it is the first video chunk, this is a silent file */
    if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
        CHUNK_PREAMBLE_SIZE)
        return AVERROR(EIO);
    chunk_type = AV_RL16(&chunk_preamble[2]);
    url_fseek(pb, -CHUNK_PREAMBLE_SIZE, SEEK_CUR);

    if (chunk_type == CHUNK_VIDEO)
        ipmovie->audio_type = 0;  /* no audio */
    else if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_AUDIO)
        return AVERROR_INVALIDDATA;

    /* initialize the stream decoders */
    st = av_new_stream(s, 0);
    if (!st)
        return AVERROR(ENOMEM);
    av_set_pts_info(st, 33, 1, 90000);
    ipmovie->video_stream_index = st->index;
    st->codec->codec_type = CODEC_TYPE_VIDEO;
    st->codec->codec_id = CODEC_ID_INTERPLAY_VIDEO;
    st->codec->codec_tag = 0;  /* no fourcc */
    st->codec->width = ipmovie->video_width;
    st->codec->height = ipmovie->video_height;

    /* palette considerations */
    st->codec->palctrl = &ipmovie->palette_control;

    if (ipmovie->audio_type) {
        st = av_new_stream(s, 0);
        if (!st)
            return AVERROR(ENOMEM);
        av_set_pts_info(st, 33, 1, 90000);
        ipmovie->audio_stream_index = st->index;
        st->codec->codec_type = CODEC_TYPE_AUDIO;
        st->codec->codec_id = ipmovie->audio_type;
        st->codec->codec_tag = 0;  /* no tag */
        st->codec->channels = ipmovie->audio_channels;
        st->codec->sample_rate = ipmovie->audio_sample_rate;
        st->codec->bits_per_sample = ipmovie->audio_bits;
        st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
            st->codec->bits_per_sample;
        if (st->codec->codec_id == CODEC_ID_INTERPLAY_DPCM)
            st->codec->bit_rate /= 2;
        st->codec->block_align = st->codec->channels * st->codec->bits_per_sample;
    }

    return 0;
}

static int ipmovie_read_packet(AVFormatContext *s,
                               AVPacket *pkt)
{
    IPMVEContext *ipmovie = s->priv_data;
    ByteIOContext *pb = &s->pb;
    int ret;

    ret = process_ipmovie_chunk(ipmovie, pb, pkt);
    if (ret == CHUNK_BAD)
        ret = AVERROR_INVALIDDATA;
    else if (ret == CHUNK_EOF)
        ret = AVERROR(EIO);
    else if (ret == CHUNK_NOMEM)
        ret = AVERROR(ENOMEM);
    else if (ret == CHUNK_VIDEO)
        ret = 0;
    else
        ret = -1;

    return ret;
}

static int ipmovie_read_close(AVFormatContext *s)
{
//    IPMVEContext *ipmovie = s->priv_data;

    return 0;
}

AVInputFormat ipmovie_demuxer = {
    "ipmovie",
    "Interplay MVE format",
    sizeof(IPMVEContext),
    ipmovie_probe,
    ipmovie_read_header,
    ipmovie_read_packet,
    ipmovie_read_close,
};