PeerStreamer

/*

 * GXF demuxer.

 * Copyright (c) 2006 Reimar Doeffinger

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavutil/common.h"

#include "avformat.h"

#include "internal.h"

#include "gxf.h"

struct gxf_stream_info {

    int64_t first_field;

    int64_t last_field;

    AVRational frames_per_second;

    int32_t fields_per_frame;

};

/**

 * \brief parses a packet header, extracting type and length

 * \param pb AVIOContext to read header from

 * \param type detected packet type is stored here

 * \param length detected packet length, excluding header is stored here

 * \return 0 if header not found or contains invalid data, 1 otherwise

 */

static int parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length) {

    if (avio_rb32(pb))

        return 0;

    if (avio_r8(pb) != 1)

        return 0;

    *type = avio_r8(pb);

    *length = avio_rb32(pb);

    if ((*length >> 24) || *length < 16)

        return 0;

    *length -= 16;

    if (avio_rb32(pb))

        return 0;

    if (avio_r8(pb) != 0xe1)

        return 0;

    if (avio_r8(pb) != 0xe2)

        return 0;

    return 1;

}

/**

 * \brief check if file starts with a PKT_MAP header

 */

static int gxf_probe(AVProbeData *p) {

    static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet

    static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};

    if (!memcmp(p->buf, startcode, sizeof(startcode)) &&

        !memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))

        return AVPROBE_SCORE_MAX;

    return 0;

}

/**

 * \brief gets the stream index for the track with the specified id, creates new

 *        stream if not found

 * \param id     id of stream to find / add

 * \param format stream format identifier

 */

static int get_sindex(AVFormatContext *s, int id, int format) {

    int i;

    AVStream *st = NULL;

    i = ff_find_stream_index(s, id);

    if (i >= 0)

        return i;

    st = av_new_stream(s, id);

    if (!st)

        return AVERROR(ENOMEM);

    switch (format) {

        case 3:

        case 4:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = CODEC_ID_MJPEG;

            break;

        case 13:

        case 15:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = CODEC_ID_DVVIDEO;

            break;

        case 14:

        case 16:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = CODEC_ID_DVVIDEO;

            break;

        case 11:

        case 12:

        case 20:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = CODEC_ID_MPEG2VIDEO;

            st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.

            break;

        case 22:

        case 23:

            st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

            st->codec->codec_id = CODEC_ID_MPEG1VIDEO;

            st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.

            break;

        case 9:

            st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

            st->codec->codec_id = CODEC_ID_PCM_S24LE;

            st->codec->channels = 1;

            st->codec->sample_rate = 48000;

            st->codec->bit_rate = 3 * 1 * 48000 * 8;

            st->codec->block_align = 3 * 1;

            st->codec->bits_per_coded_sample = 24;

            break;

        case 10:

            st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

            st->codec->codec_id = CODEC_ID_PCM_S16LE;

            st->codec->channels = 1;

            st->codec->sample_rate = 48000;

            st->codec->bit_rate = 2 * 1 * 48000 * 8;

            st->codec->block_align = 2 * 1;

            st->codec->bits_per_coded_sample = 16;

            break;

        case 17:

            st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

            st->codec->codec_id = CODEC_ID_AC3;

            st->codec->channels = 2;

            st->codec->sample_rate = 48000;

            break;

        // timecode tracks:

        case 7:

        case 8:

        case 24:

            st->codec->codec_type = AVMEDIA_TYPE_DATA;

            st->codec->codec_id = CODEC_ID_NONE;

            break;

        default:

            st->codec->codec_type = AVMEDIA_TYPE_UNKNOWN;

            st->codec->codec_id = CODEC_ID_NONE;

            break;

    }

    return s->nb_streams - 1;

}

/**

 * \brief filters out interesting tags from material information.

 * \param len length of tag section, will be adjusted to contain remaining bytes

 * \param si struct to store collected information into

 */

static void gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {

    si->first_field = AV_NOPTS_VALUE;

    si->last_field = AV_NOPTS_VALUE;

    while (*len >= 2) {

        GXFMatTag tag = avio_r8(pb);

        int tlen = avio_r8(pb);

        *len -= 2;

        if (tlen > *len)

            return;

        *len -= tlen;

        if (tlen == 4) {

            uint32_t value = avio_rb32(pb);

            if (tag == MAT_FIRST_FIELD)

                si->first_field = value;

            else if (tag == MAT_LAST_FIELD)

                si->last_field = value;

        } else

            avio_seek(pb, tlen, SEEK_CUR);

    }

}

/**

 * \brief convert fps tag value to AVRational fps

 * \param fps fps value from tag

 * \return fps as AVRational, or 0 / 0 if unknown

 */

static AVRational fps_tag2avr(int32_t fps) {

    extern const AVRational ff_frame_rate_tab[];

    if (fps < 1 || fps > 9) fps = 9;

    return ff_frame_rate_tab[9 - fps]; // values have opposite order

}

/**

 * \brief convert UMF attributes flags to AVRational fps

 * \param flags UMF flags to convert

 * \return fps as AVRational, or 0 / 0 if unknown

 */

static AVRational fps_umf2avr(uint32_t flags) {

    static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},

        {25, 1}, {30000, 1001}};

    int idx =  av_log2((flags & 0x7c0) >> 6);

    return map[idx];

}

/**

 * \brief filters out interesting tags from track information.

 * \param len length of tag section, will be adjusted to contain remaining bytes

 * \param si struct to store collected information into

 */

static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {

    si->frames_per_second = (AVRational){0, 0};

    si->fields_per_frame = 0;

    while (*len >= 2) {

        GXFTrackTag tag = avio_r8(pb);

        int tlen = avio_r8(pb);

        *len -= 2;

        if (tlen > *len)

            return;

        *len -= tlen;

        if (tlen == 4) {

            uint32_t value = avio_rb32(pb);

            if (tag == TRACK_FPS)

                si->frames_per_second = fps_tag2avr(value);

            else if (tag == TRACK_FPF && (value == 1 || value == 2))

                si->fields_per_frame = value;

        } else

            avio_seek(pb, tlen, SEEK_CUR);

    }

}

/**

 * \brief read index from FLT packet into stream 0 av_index

 */

static void gxf_read_index(AVFormatContext *s, int pkt_len) {

    AVIOContext *pb = s->pb;

    AVStream *st = s->streams[0];

    uint32_t fields_per_map = avio_rl32(pb);

    uint32_t map_cnt = avio_rl32(pb);

    int i;

    pkt_len -= 8;

    if (s->flags & AVFMT_FLAG_IGNIDX) {

        avio_seek(pb, pkt_len, SEEK_CUR);

        return;

    }

    if (map_cnt > 1000) {

        av_log(s, AV_LOG_ERROR, "too many index entries %u (%x)\n", map_cnt, map_cnt);

        map_cnt = 1000;

    }

    if (pkt_len < 4 * map_cnt) {

        av_log(s, AV_LOG_ERROR, "invalid index length\n");

        avio_seek(pb, pkt_len, SEEK_CUR);

        return;

    }

    pkt_len -= 4 * map_cnt;

    av_add_index_entry(st, 0, 0, 0, 0, 0);

    for (i = 0; i < map_cnt; i++)

        av_add_index_entry(st, (uint64_t)avio_rl32(pb) * 1024,

                           i * (uint64_t)fields_per_map + 1, 0, 0, 0);

    avio_seek(pb, pkt_len, SEEK_CUR);

}

static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {

    AVIOContext *pb = s->pb;

    GXFPktType pkt_type;

    int map_len;

    int len;

    AVRational main_timebase = {0, 0};

    struct gxf_stream_info si;

    int i;

    if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {

        av_log(s, AV_LOG_ERROR, "map packet not found\n");

        return 0;

    }

    map_len -= 2;

    if (avio_r8(pb) != 0x0e0 || avio_r8(pb) != 0xff) {

        av_log(s, AV_LOG_ERROR, "unknown version or invalid map preamble\n");

        return 0;

    }

    map_len -= 2;

    len = avio_rb16(pb); // length of material data section

    if (len > map_len) {

        av_log(s, AV_LOG_ERROR, "material data longer than map data\n");

        return 0;

    }

    map_len -= len;

    gxf_material_tags(pb, &len, &si);

    avio_seek(pb, len, SEEK_CUR);

    map_len -= 2;

    len = avio_rb16(pb); // length of track description

    if (len > map_len) {

        av_log(s, AV_LOG_ERROR, "track description longer than map data\n");

        return 0;

    }

    map_len -= len;

    while (len > 0) {

        int track_type, track_id, track_len;

        AVStream *st;

        int idx;

        len -= 4;

        track_type = avio_r8(pb);

        track_id = avio_r8(pb);

        track_len = avio_rb16(pb);

        len -= track_len;

        gxf_track_tags(pb, &track_len, &si);

        avio_seek(pb, track_len, SEEK_CUR);

        if (!(track_type & 0x80)) {

           av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);

           continue;

        }

        track_type &= 0x7f;

        if ((track_id & 0xc0) != 0xc0) {

           av_log(s, AV_LOG_ERROR, "invalid track id %x\n", track_id);

           continue;

        }

        track_id &= 0x3f;

        idx = get_sindex(s, track_id, track_type);

        if (idx < 0) continue;

        st = s->streams[idx];

        if (!main_timebase.num || !main_timebase.den) {

            main_timebase.num = si.frames_per_second.den;

            main_timebase.den = si.frames_per_second.num * 2;

        }

        st->start_time = si.first_field;

        if (si.first_field != AV_NOPTS_VALUE && si.last_field != AV_NOPTS_VALUE)

            st->duration = si.last_field - si.first_field;

    }

    if (len < 0)

        av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");

    if (map_len)

        avio_seek(pb, map_len, SEEK_CUR);

    if (!parse_packet_header(pb, &pkt_type, &len)) {

        av_log(s, AV_LOG_ERROR, "sync lost in header\n");

        return -1;

    }

    if (pkt_type == PKT_FLT) {

        gxf_read_index(s, len);

        if (!parse_packet_header(pb, &pkt_type, &len)) {

            av_log(s, AV_LOG_ERROR, "sync lost in header\n");

            return -1;

        }

    }

    if (pkt_type == PKT_UMF) {

        if (len >= 0x39) {

            AVRational fps;

            len -= 0x39;

            avio_seek(pb, 5, SEEK_CUR); // preamble

            avio_seek(pb, 0x30, SEEK_CUR); // payload description

            fps = fps_umf2avr(avio_rl32(pb));

            if (!main_timebase.num || !main_timebase.den) {

                // this may not always be correct, but simply the best we can get

                main_timebase.num = fps.den;

                main_timebase.den = fps.num * 2;

            }

        } else

            av_log(s, AV_LOG_INFO, "UMF packet too short\n");

    } else

        av_log(s, AV_LOG_INFO, "UMF packet missing\n");

    avio_seek(pb, len, SEEK_CUR);

    // set a fallback value, 60000/1001 is specified for audio-only files

    // so use that regardless of why we do not know the video frame rate.

    if (!main_timebase.num || !main_timebase.den)

        main_timebase = (AVRational){1001, 60000};

    for (i = 0; i < s->nb_streams; i++) {

        AVStream *st = s->streams[i];

        av_set_pts_info(st, 32, main_timebase.num, main_timebase.den);

    }

    return 0;

}

#define READ_ONE() \

    { \

        if (!max_interval-- || url_feof(pb)) \

            goto out; \

        tmp = tmp << 8 | avio_r8(pb); \

    }

/**

 * \brief resync the stream on the next media packet with specified properties

 * \param max_interval how many bytes to search for matching packet at most

 * \param track track id the media packet must belong to, -1 for any

 * \param timestamp minimum timestamp (== field number) the packet must have, -1 for any

 * \return timestamp of packet found

 */

static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {

    uint32_t tmp;

    uint64_t last_pos;

    uint64_t last_found_pos = 0;

    int cur_track;

    int64_t cur_timestamp = AV_NOPTS_VALUE;

    int len;

    AVIOContext *pb = s->pb;

    GXFPktType type;

    tmp = avio_rb32(pb);

start:

    while (tmp)

        READ_ONE();

    READ_ONE();

    if (tmp != 1)

        goto start;

    last_pos = avio_tell(pb);

    if (avio_seek(pb, -5, SEEK_CUR) < 0)

        goto out;

    if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {

        if (avio_seek(pb, last_pos, SEEK_SET) < 0)

            goto out;

        goto start;

    }

    avio_r8(pb);

    cur_track = avio_r8(pb);

    cur_timestamp = avio_rb32(pb);

    last_found_pos = avio_tell(pb) - 16 - 6;

    if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {

        if (avio_seek(pb, last_pos, SEEK_SET) >= 0)

            goto start;

    }

out:

    if (last_found_pos)

        avio_seek(pb, last_found_pos, SEEK_SET);

    return cur_timestamp;

}

static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {

    AVIOContext *pb = s->pb;

    GXFPktType pkt_type;

    int pkt_len;

    while (!url_feof(pb)) {

        AVStream *st;

        int track_type, track_id, ret;

        int field_nr, field_info, skip = 0;

        int stream_index;

        if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {

            if (!url_feof(pb))

                av_log(s, AV_LOG_ERROR, "sync lost\n");

            return -1;

        }

        if (pkt_type == PKT_FLT) {

            gxf_read_index(s, pkt_len);

            continue;

        }

        if (pkt_type != PKT_MEDIA) {

            avio_seek(pb, pkt_len, SEEK_CUR);

            continue;

        }

        if (pkt_len < 16) {

            av_log(s, AV_LOG_ERROR, "invalid media packet length\n");

            continue;

        }

        pkt_len -= 16;

        track_type = avio_r8(pb);

        track_id = avio_r8(pb);

        stream_index = get_sindex(s, track_id, track_type);

        if (stream_index < 0)

            return stream_index;

        st = s->streams[stream_index];

        field_nr = avio_rb32(pb);

        field_info = avio_rb32(pb);

        avio_rb32(pb); // "timeline" field number

        avio_r8(pb); // flags

        avio_r8(pb); // reserved

        if (st->codec->codec_id == CODEC_ID_PCM_S24LE ||

            st->codec->codec_id == CODEC_ID_PCM_S16LE) {

            int first = field_info >> 16;

            int last  = field_info & 0xffff; // last is exclusive

            int bps = av_get_bits_per_sample(st->codec->codec_id)>>3;

            if (first <= last && last*bps <= pkt_len) {

                avio_seek(pb, first*bps, SEEK_CUR);

                skip = pkt_len - last*bps;

                pkt_len = (last-first)*bps;

            } else

                av_log(s, AV_LOG_ERROR, "invalid first and last sample values\n");

        }

        ret = av_get_packet(pb, pkt, pkt_len);

        if (skip)

            avio_seek(pb, skip, SEEK_CUR);

        pkt->stream_index = stream_index;

        pkt->dts = field_nr;

        return ret;

    }

    return AVERROR(EIO);

}

static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {

    int res = 0;

    uint64_t pos;

    uint64_t maxlen = 100 * 1024 * 1024;

    AVStream *st = s->streams[0];

    int64_t start_time = s->streams[stream_index]->start_time;

    int64_t found;

    int idx;

    if (timestamp < start_time) timestamp = start_time;

    idx = av_index_search_timestamp(st, timestamp - start_time,

                                    AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);

    if (idx < 0)

        return -1;

    pos = st->index_entries[idx].pos;

    if (idx < st->nb_index_entries - 2)

        maxlen = st->index_entries[idx + 2].pos - pos;

    maxlen = FFMAX(maxlen, 200 * 1024);

    res = avio_seek(s->pb, pos, SEEK_SET);

    if (res < 0)

        return res;

    found = gxf_resync_media(s, maxlen, -1, timestamp);

    if (FFABS(found - timestamp) > 4)

        return -1;

    return 0;

}

static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,

                                  int64_t *pos, int64_t pos_limit) {

    AVIOContext *pb = s->pb;

    int64_t res;

    if (avio_seek(pb, *pos, SEEK_SET) < 0)

        return AV_NOPTS_VALUE;

    res = gxf_resync_media(s, pos_limit - *pos, -1, -1);

    *pos = avio_tell(pb);

    return res;

}

AVInputFormat ff_gxf_demuxer = {

    "gxf",

    NULL_IF_CONFIG_SMALL("GXF format"),

    0,

    gxf_probe,

    gxf_header,

    gxf_packet,

    NULL,

    gxf_seek,

    gxf_read_timestamp,

};