yading@11: /*
yading@11:  * GXF demuxer.
yading@11:  * Copyright (c) 2006 Reimar Doeffinger
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/channel_layout.h"
yading@11: #include "libavutil/common.h"
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: #include "gxf.h"
yading@11: #include "libavcodec/mpeg12data.h"
yading@11: 
yading@11: struct gxf_stream_info {
yading@11:     int64_t first_field;
yading@11:     int64_t last_field;
yading@11:     AVRational frames_per_second;
yading@11:     int32_t fields_per_frame;
yading@11:     int64_t track_aux_data;
yading@11: };
yading@11: 
yading@11: /**
yading@11:  * @brief parse gxf timecode and add it to metadata
yading@11:  */
yading@11: static int add_timecode_metadata(AVDictionary **pm, const char *key, uint32_t timecode, int fields_per_frame)
yading@11: {
yading@11:    char tmp[128];
yading@11:    int field  = timecode & 0xff;
yading@11:    int frame  = fields_per_frame ? field / fields_per_frame : field;
yading@11:    int second = (timecode >>  8) & 0xff;
yading@11:    int minute = (timecode >> 16) & 0xff;
yading@11:    int hour   = (timecode >> 24) & 0x1f;
yading@11:    int drop   = (timecode >> 29) & 1;
yading@11:    // bit 30: color_frame, unused
yading@11:    // ignore invalid time code
yading@11:    if (timecode >> 31)
yading@11:        return 0;
yading@11:    snprintf(tmp, sizeof(tmp), "%02d:%02d:%02d%c%02d",
yading@11:        hour, minute, second, drop ? ';' : ':', frame);
yading@11:    return av_dict_set(pm, key, tmp, 0);
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief parses a packet header, extracting type and length
yading@11:  * @param pb AVIOContext to read header from
yading@11:  * @param type detected packet type is stored here
yading@11:  * @param length detected packet length, excluding header is stored here
yading@11:  * @return 0 if header not found or contains invalid data, 1 otherwise
yading@11:  */
yading@11: static int parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length) {
yading@11:     if (avio_rb32(pb))
yading@11:         return 0;
yading@11:     if (avio_r8(pb) != 1)
yading@11:         return 0;
yading@11:     *type = avio_r8(pb);
yading@11:     *length = avio_rb32(pb);
yading@11:     if ((*length >> 24) || *length < 16)
yading@11:         return 0;
yading@11:     *length -= 16;
yading@11:     if (avio_rb32(pb))
yading@11:         return 0;
yading@11:     if (avio_r8(pb) != 0xe1)
yading@11:         return 0;
yading@11:     if (avio_r8(pb) != 0xe2)
yading@11:         return 0;
yading@11:     return 1;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief check if file starts with a PKT_MAP header
yading@11:  */
yading@11: static int gxf_probe(AVProbeData *p) {
yading@11:     static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet
yading@11:     static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};
yading@11:     if (!memcmp(p->buf, startcode, sizeof(startcode)) &&
yading@11:         !memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))
yading@11:         return AVPROBE_SCORE_MAX;
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief gets the stream index for the track with the specified id, creates new
yading@11:  *        stream if not found
yading@11:  * @param id     id of stream to find / add
yading@11:  * @param format stream format identifier
yading@11:  */
yading@11: static int get_sindex(AVFormatContext *s, int id, int format) {
yading@11:     int i;
yading@11:     AVStream *st = NULL;
yading@11:     i = ff_find_stream_index(s, id);
yading@11:     if (i >= 0)
yading@11:         return i;
yading@11:     st = avformat_new_stream(s, NULL);
yading@11:     if (!st)
yading@11:         return AVERROR(ENOMEM);
yading@11:     st->id = id;
yading@11:     switch (format) {
yading@11:         case 3:
yading@11:         case 4:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_MJPEG;
yading@11:             break;
yading@11:         case 13:
yading@11:         case 15:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_DVVIDEO;
yading@11:             break;
yading@11:         case 14:
yading@11:         case 16:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_DVVIDEO;
yading@11:             break;
yading@11:         case 11:
yading@11:         case 12:
yading@11:         case 20:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_MPEG2VIDEO;
yading@11:             st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
yading@11:             break;
yading@11:         case 22:
yading@11:         case 23:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_MPEG1VIDEO;
yading@11:             st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
yading@11:             break;
yading@11:         case 9:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_PCM_S24LE;
yading@11:             st->codec->channels = 1;
yading@11:             st->codec->channel_layout = AV_CH_LAYOUT_MONO;
yading@11:             st->codec->sample_rate = 48000;
yading@11:             st->codec->bit_rate = 3 * 1 * 48000 * 8;
yading@11:             st->codec->block_align = 3 * 1;
yading@11:             st->codec->bits_per_coded_sample = 24;
yading@11:             break;
yading@11:         case 10:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_PCM_S16LE;
yading@11:             st->codec->channels = 1;
yading@11:             st->codec->channel_layout = AV_CH_LAYOUT_MONO;
yading@11:             st->codec->sample_rate = 48000;
yading@11:             st->codec->bit_rate = 2 * 1 * 48000 * 8;
yading@11:             st->codec->block_align = 2 * 1;
yading@11:             st->codec->bits_per_coded_sample = 16;
yading@11:             break;
yading@11:         case 17:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
yading@11:             st->codec->codec_id = AV_CODEC_ID_AC3;
yading@11:             st->codec->channels = 2;
yading@11:             st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
yading@11:             st->codec->sample_rate = 48000;
yading@11:             break;
yading@11:         // timecode tracks:
yading@11:         case 7:
yading@11:         case 8:
yading@11:         case 24:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_DATA;
yading@11:             st->codec->codec_id = AV_CODEC_ID_NONE;
yading@11:             break;
yading@11:         default:
yading@11:             st->codec->codec_type = AVMEDIA_TYPE_UNKNOWN;
yading@11:             st->codec->codec_id = AV_CODEC_ID_NONE;
yading@11:             break;
yading@11:     }
yading@11:     return s->nb_streams - 1;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief filters out interesting tags from material information.
yading@11:  * @param len length of tag section, will be adjusted to contain remaining bytes
yading@11:  * @param si struct to store collected information into
yading@11:  */
yading@11: static void gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
yading@11:     si->first_field = AV_NOPTS_VALUE;
yading@11:     si->last_field = AV_NOPTS_VALUE;
yading@11:     while (*len >= 2) {
yading@11:         GXFMatTag tag = avio_r8(pb);
yading@11:         int tlen = avio_r8(pb);
yading@11:         *len -= 2;
yading@11:         if (tlen > *len)
yading@11:             return;
yading@11:         *len -= tlen;
yading@11:         if (tlen == 4) {
yading@11:             uint32_t value = avio_rb32(pb);
yading@11:             if (tag == MAT_FIRST_FIELD)
yading@11:                 si->first_field = value;
yading@11:             else if (tag == MAT_LAST_FIELD)
yading@11:                 si->last_field = value;
yading@11:         } else
yading@11:             avio_skip(pb, tlen);
yading@11:     }
yading@11: }
yading@11: 
yading@11: static const AVRational frame_rate_tab[] = {
yading@11:     {   60,    1},
yading@11:     {60000, 1001},
yading@11:     {   50,    1},
yading@11:     {   30,    1},
yading@11:     {30000, 1001},
yading@11:     {   25,    1},
yading@11:     {   24,    1},
yading@11:     {24000, 1001},
yading@11:     {    0,    0},
yading@11: };
yading@11: 
yading@11: /**
yading@11:  * @brief convert fps tag value to AVRational fps
yading@11:  * @param fps fps value from tag
yading@11:  * @return fps as AVRational, or 0 / 0 if unknown
yading@11:  */
yading@11: static AVRational fps_tag2avr(int32_t fps) {
yading@11:     if (fps < 1 || fps > 9) fps = 9;
yading@11:     return frame_rate_tab[fps - 1];
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief convert UMF attributes flags to AVRational fps
yading@11:  * @param flags UMF flags to convert
yading@11:  * @return fps as AVRational, or 0 / 0 if unknown
yading@11:  */
yading@11: static AVRational fps_umf2avr(uint32_t flags) {
yading@11:     static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
yading@11:         {25, 1}, {30000, 1001}};
yading@11:     int idx =  av_log2((flags & 0x7c0) >> 6);
yading@11:     return map[idx];
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief filters out interesting tags from track information.
yading@11:  * @param len length of tag section, will be adjusted to contain remaining bytes
yading@11:  * @param si struct to store collected information into
yading@11:  */
yading@11: static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
yading@11:     si->frames_per_second = (AVRational){0, 0};
yading@11:     si->fields_per_frame = 0;
yading@11:     si->track_aux_data = 0x80000000;
yading@11:     while (*len >= 2) {
yading@11:         GXFTrackTag tag = avio_r8(pb);
yading@11:         int tlen = avio_r8(pb);
yading@11:         *len -= 2;
yading@11:         if (tlen > *len)
yading@11:             return;
yading@11:         *len -= tlen;
yading@11:         if (tlen == 4) {
yading@11:             uint32_t value = avio_rb32(pb);
yading@11:             if (tag == TRACK_FPS)
yading@11:                 si->frames_per_second = fps_tag2avr(value);
yading@11:             else if (tag == TRACK_FPF && (value == 1 || value == 2))
yading@11:                 si->fields_per_frame = value;
yading@11:         } else if (tlen == 8 && tag == TRACK_AUX)
yading@11:             si->track_aux_data = avio_rl64(pb);
yading@11:         else
yading@11:             avio_skip(pb, tlen);
yading@11:     }
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * @brief read index from FLT packet into stream 0 av_index
yading@11:  */
yading@11: static void gxf_read_index(AVFormatContext *s, int pkt_len) {
yading@11:     AVIOContext *pb = s->pb;
yading@11:     AVStream *st;
yading@11:     uint32_t fields_per_map = avio_rl32(pb);
yading@11:     uint32_t map_cnt = avio_rl32(pb);
yading@11:     int i;
yading@11:     pkt_len -= 8;
yading@11:     if ((s->flags & AVFMT_FLAG_IGNIDX) || !s->streams) {
yading@11:         avio_skip(pb, pkt_len);
yading@11:         return;
yading@11:     }
yading@11:     st = s->streams[0];
yading@11:     if (map_cnt > 1000) {
yading@11:         av_log(s, AV_LOG_ERROR, "too many index entries %u (%x)\n", map_cnt, map_cnt);
yading@11:         map_cnt = 1000;
yading@11:     }
yading@11:     if (pkt_len < 4 * map_cnt) {
yading@11:         av_log(s, AV_LOG_ERROR, "invalid index length\n");
yading@11:         avio_skip(pb, pkt_len);
yading@11:         return;
yading@11:     }
yading@11:     pkt_len -= 4 * map_cnt;
yading@11:     av_add_index_entry(st, 0, 0, 0, 0, 0);
yading@11:     for (i = 0; i < map_cnt; i++)
yading@11:         av_add_index_entry(st, (uint64_t)avio_rl32(pb) * 1024,
yading@11:                            i * (uint64_t)fields_per_map + 1, 0, 0, 0);
yading@11:     avio_skip(pb, pkt_len);
yading@11: }
yading@11: 
yading@11: static int gxf_header(AVFormatContext *s) {
yading@11:     AVIOContext *pb = s->pb;
yading@11:     GXFPktType pkt_type;
yading@11:     int map_len;
yading@11:     int len;
yading@11:     AVRational main_timebase = {0, 0};
yading@11:     struct gxf_stream_info *si = s->priv_data;
yading@11:     int i;
yading@11:     if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
yading@11:         av_log(s, AV_LOG_ERROR, "map packet not found\n");
yading@11:         return 0;
yading@11:     }
yading@11:     map_len -= 2;
yading@11:     if (avio_r8(pb) != 0x0e0 || avio_r8(pb) != 0xff) {
yading@11:         av_log(s, AV_LOG_ERROR, "unknown version or invalid map preamble\n");
yading@11:         return 0;
yading@11:     }
yading@11:     map_len -= 2;
yading@11:     len = avio_rb16(pb); // length of material data section
yading@11:     if (len > map_len) {
yading@11:         av_log(s, AV_LOG_ERROR, "material data longer than map data\n");
yading@11:         return 0;
yading@11:     }
yading@11:     map_len -= len;
yading@11:     gxf_material_tags(pb, &len, si);
yading@11:     avio_skip(pb, len);
yading@11:     map_len -= 2;
yading@11:     len = avio_rb16(pb); // length of track description
yading@11:     if (len > map_len) {
yading@11:         av_log(s, AV_LOG_ERROR, "track description longer than map data\n");
yading@11:         return 0;
yading@11:     }
yading@11:     map_len -= len;
yading@11:     while (len > 0) {
yading@11:         int track_type, track_id, track_len;
yading@11:         AVStream *st;
yading@11:         int idx;
yading@11:         len -= 4;
yading@11:         track_type = avio_r8(pb);
yading@11:         track_id = avio_r8(pb);
yading@11:         track_len = avio_rb16(pb);
yading@11:         len -= track_len;
yading@11:         if (!(track_type & 0x80)) {
yading@11:            av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);
yading@11:            continue;
yading@11:         }
yading@11:         track_type &= 0x7f;
yading@11:         if ((track_id & 0xc0) != 0xc0) {
yading@11:            av_log(s, AV_LOG_ERROR, "invalid track id %x\n", track_id);
yading@11:            continue;
yading@11:         }
yading@11:         track_id &= 0x3f;
yading@11:         gxf_track_tags(pb, &track_len, si);
yading@11:         // check for timecode tracks
yading@11:         if (track_type == 7 || track_type == 8 || track_type == 24) {
yading@11:             add_timecode_metadata(&s->metadata, "timecode",
yading@11:                                   si->track_aux_data & 0xffffffff,
yading@11:                                   si->fields_per_frame);
yading@11: 
yading@11:         }
yading@11:         avio_skip(pb, track_len);
yading@11: 
yading@11:         idx = get_sindex(s, track_id, track_type);
yading@11:         if (idx < 0) continue;
yading@11:         st = s->streams[idx];
yading@11:         if (!main_timebase.num || !main_timebase.den) {
yading@11:             main_timebase.num = si->frames_per_second.den;
yading@11:             main_timebase.den = si->frames_per_second.num * 2;
yading@11:         }
yading@11:         st->start_time = si->first_field;
yading@11:         if (si->first_field != AV_NOPTS_VALUE && si->last_field != AV_NOPTS_VALUE)
yading@11:             st->duration = si->last_field - si->first_field;
yading@11:     }
yading@11:     if (len < 0)
yading@11:         av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");
yading@11:     if (map_len)
yading@11:         avio_skip(pb, map_len);
yading@11:     if (!parse_packet_header(pb, &pkt_type, &len)) {
yading@11:         av_log(s, AV_LOG_ERROR, "sync lost in header\n");
yading@11:         return -1;
yading@11:     }
yading@11:     if (pkt_type == PKT_FLT) {
yading@11:         gxf_read_index(s, len);
yading@11:         if (!parse_packet_header(pb, &pkt_type, &len)) {
yading@11:             av_log(s, AV_LOG_ERROR, "sync lost in header\n");
yading@11:             return -1;
yading@11:         }
yading@11:     }
yading@11:     if (pkt_type == PKT_UMF) {
yading@11:         if (len >= 0x39) {
yading@11:             AVRational fps;
yading@11:             len -= 0x39;
yading@11:             avio_skip(pb, 5); // preamble
yading@11:             avio_skip(pb, 0x30); // payload description
yading@11:             fps = fps_umf2avr(avio_rl32(pb));
yading@11:             if (!main_timebase.num || !main_timebase.den) {
yading@11:                 av_log(s, AV_LOG_WARNING, "No FPS track tag, using UMF fps tag."
yading@11:                                           " This might give wrong results.\n");
yading@11:                 // this may not always be correct, but simply the best we can get
yading@11:                 main_timebase.num = fps.den;
yading@11:                 main_timebase.den = fps.num * 2;
yading@11:             }
yading@11: 
yading@11:             if (len >= 0x18) {
yading@11:                 len -= 0x18;
yading@11:                 avio_skip(pb, 0x10);
yading@11:                 add_timecode_metadata(&s->metadata, "timecode_at_mark_in",
yading@11:                                       avio_rl32(pb), si->fields_per_frame);
yading@11:                 add_timecode_metadata(&s->metadata, "timecode_at_mark_out",
yading@11:                                       avio_rl32(pb), si->fields_per_frame);
yading@11:             }
yading@11:         } else
yading@11:             av_log(s, AV_LOG_INFO, "UMF packet too short\n");
yading@11:     } else
yading@11:         av_log(s, AV_LOG_INFO, "UMF packet missing\n");
yading@11:     avio_skip(pb, len);
yading@11:     // set a fallback value, 60000/1001 is specified for audio-only files
yading@11:     // so use that regardless of why we do not know the video frame rate.
yading@11:     if (!main_timebase.num || !main_timebase.den)
yading@11:         main_timebase = (AVRational){1001, 60000};
yading@11:     for (i = 0; i < s->nb_streams; i++) {
yading@11:         AVStream *st = s->streams[i];
yading@11:         avpriv_set_pts_info(st, 32, main_timebase.num, main_timebase.den);
yading@11:     }
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: #define READ_ONE() \
yading@11:     { \
yading@11:         if (!max_interval-- || url_feof(pb)) \
yading@11:             goto out; \
yading@11:         tmp = tmp << 8 | avio_r8(pb); \
yading@11:     }
yading@11: 
yading@11: /**
yading@11:  * @brief resync the stream on the next media packet with specified properties
yading@11:  * @param max_interval how many bytes to search for matching packet at most
yading@11:  * @param track track id the media packet must belong to, -1 for any
yading@11:  * @param timestamp minimum timestamp (== field number) the packet must have, -1 for any
yading@11:  * @return timestamp of packet found
yading@11:  */
yading@11: static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
yading@11:     uint32_t tmp;
yading@11:     uint64_t last_pos;
yading@11:     uint64_t last_found_pos = 0;
yading@11:     int cur_track;
yading@11:     int64_t cur_timestamp = AV_NOPTS_VALUE;
yading@11:     int len;
yading@11:     AVIOContext *pb = s->pb;
yading@11:     GXFPktType type;
yading@11:     tmp = avio_rb32(pb);
yading@11: start:
yading@11:     while (tmp)
yading@11:         READ_ONE();
yading@11:     READ_ONE();
yading@11:     if (tmp != 1)
yading@11:         goto start;
yading@11:     last_pos = avio_tell(pb);
yading@11:     if (avio_seek(pb, -5, SEEK_CUR) < 0)
yading@11:         goto out;
yading@11:     if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
yading@11:         if (avio_seek(pb, last_pos, SEEK_SET) < 0)
yading@11:             goto out;
yading@11:         goto start;
yading@11:     }
yading@11:     avio_r8(pb);
yading@11:     cur_track = avio_r8(pb);
yading@11:     cur_timestamp = avio_rb32(pb);
yading@11:     last_found_pos = avio_tell(pb) - 16 - 6;
yading@11:     if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
yading@11:         if (avio_seek(pb, last_pos, SEEK_SET) >= 0)
yading@11:             goto start;
yading@11:     }
yading@11: out:
yading@11:     if (last_found_pos)
yading@11:         avio_seek(pb, last_found_pos, SEEK_SET);
yading@11:     return cur_timestamp;
yading@11: }
yading@11: 
yading@11: static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
yading@11:     AVIOContext *pb = s->pb;
yading@11:     GXFPktType pkt_type;
yading@11:     int pkt_len;
yading@11:     struct gxf_stream_info *si = s->priv_data;
yading@11: 
yading@11:     while (!pb->eof_reached) {
yading@11:         AVStream *st;
yading@11:         int track_type, track_id, ret;
yading@11:         int field_nr, field_info, skip = 0;
yading@11:         int stream_index;
yading@11:         if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
yading@11:             if (!url_feof(pb))
yading@11:                 av_log(s, AV_LOG_ERROR, "sync lost\n");
yading@11:             return -1;
yading@11:         }
yading@11:         if (pkt_type == PKT_FLT) {
yading@11:             gxf_read_index(s, pkt_len);
yading@11:             continue;
yading@11:         }
yading@11:         if (pkt_type != PKT_MEDIA) {
yading@11:             avio_skip(pb, pkt_len);
yading@11:             continue;
yading@11:         }
yading@11:         if (pkt_len < 16) {
yading@11:             av_log(s, AV_LOG_ERROR, "invalid media packet length\n");
yading@11:             continue;
yading@11:         }
yading@11:         pkt_len -= 16;
yading@11:         track_type = avio_r8(pb);
yading@11:         track_id = avio_r8(pb);
yading@11:         stream_index = get_sindex(s, track_id, track_type);
yading@11:         if (stream_index < 0)
yading@11:             return stream_index;
yading@11:         st = s->streams[stream_index];
yading@11:         field_nr = avio_rb32(pb);
yading@11:         field_info = avio_rb32(pb);
yading@11:         avio_rb32(pb); // "timeline" field number
yading@11:         avio_r8(pb); // flags
yading@11:         avio_r8(pb); // reserved
yading@11:         if (st->codec->codec_id == AV_CODEC_ID_PCM_S24LE ||
yading@11:             st->codec->codec_id == AV_CODEC_ID_PCM_S16LE) {
yading@11:             int first = field_info >> 16;
yading@11:             int last  = field_info & 0xffff; // last is exclusive
yading@11:             int bps = av_get_bits_per_sample(st->codec->codec_id)>>3;
yading@11:             if (first <= last && last*bps <= pkt_len) {
yading@11:                 avio_skip(pb, first*bps);
yading@11:                 skip = pkt_len - last*bps;
yading@11:                 pkt_len = (last-first)*bps;
yading@11:             } else
yading@11:                 av_log(s, AV_LOG_ERROR, "invalid first and last sample values\n");
yading@11:         }
yading@11:         ret = av_get_packet(pb, pkt, pkt_len);
yading@11:         if (skip)
yading@11:             avio_skip(pb, skip);
yading@11:         pkt->stream_index = stream_index;
yading@11:         pkt->dts = field_nr;
yading@11: 
yading@11:         //set duration manually for DV or else lavf misdetects the frame rate
yading@11:         if (st->codec->codec_id == AV_CODEC_ID_DVVIDEO)
yading@11:             pkt->duration = si->fields_per_frame;
yading@11: 
yading@11:         return ret;
yading@11:     }
yading@11:     return AVERROR_EOF;
yading@11: }
yading@11: 
yading@11: static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
yading@11:     int res = 0;
yading@11:     uint64_t pos;
yading@11:     uint64_t maxlen = 100 * 1024 * 1024;
yading@11:     AVStream *st = s->streams[0];
yading@11:     int64_t start_time = s->streams[stream_index]->start_time;
yading@11:     int64_t found;
yading@11:     int idx;
yading@11:     if (timestamp < start_time) timestamp = start_time;
yading@11:     idx = av_index_search_timestamp(st, timestamp - start_time,
yading@11:                                     AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);
yading@11:     if (idx < 0)
yading@11:         return -1;
yading@11:     pos = st->index_entries[idx].pos;
yading@11:     if (idx < st->nb_index_entries - 2)
yading@11:         maxlen = st->index_entries[idx + 2].pos - pos;
yading@11:     maxlen = FFMAX(maxlen, 200 * 1024);
yading@11:     res = avio_seek(s->pb, pos, SEEK_SET);
yading@11:     if (res < 0)
yading@11:         return res;
yading@11:     found = gxf_resync_media(s, maxlen, -1, timestamp);
yading@11:     if (FFABS(found - timestamp) > 4)
yading@11:         return -1;
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
yading@11:                                   int64_t *pos, int64_t pos_limit) {
yading@11:     AVIOContext *pb = s->pb;
yading@11:     int64_t res;
yading@11:     if (avio_seek(pb, *pos, SEEK_SET) < 0)
yading@11:         return AV_NOPTS_VALUE;
yading@11:     res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
yading@11:     *pos = avio_tell(pb);
yading@11:     return res;
yading@11: }
yading@11: 
yading@11: AVInputFormat ff_gxf_demuxer = {
yading@11:     .name           = "gxf",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("GXF (General eXchange Format)"),
yading@11:     .priv_data_size = sizeof(struct gxf_stream_info),
yading@11:     .read_probe     = gxf_probe,
yading@11:     .read_header    = gxf_header,
yading@11:     .read_packet    = gxf_packet,
yading@11:     .read_seek      = gxf_seek,
yading@11:     .read_timestamp = gxf_read_timestamp,
yading@11: };