1 /*
2  * GXF demuxer.
3  * Copyright (c) 2006 Reimar Doeffinger
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <inttypes.h>
23 
24 #include "libavutil/channel_layout.h"
25 #include "libavutil/common.h"
26 #include "avformat.h"
27 #include "demux.h"
28 #include "internal.h"
29 #include "gxf.h"
30 
31 struct gxf_stream_info {
32     int64_t first_field;
33     int64_t last_field;
34     AVRational frames_per_second;
35     int32_t fields_per_frame;
36     int64_t track_aux_data;
37 };
38 
39 /**
40  * @brief parse gxf timecode and add it to metadata
41  */
add_timecode_metadata(AVDictionary **pm, const char *key, uint32_t timecode, int fields_per_frame)42 static int add_timecode_metadata(AVDictionary **pm, const char *key, uint32_t timecode, int fields_per_frame)
43 {
44    char tmp[128];
45    int field  = timecode & 0xff;
46    int frame  = fields_per_frame ? field / fields_per_frame : field;
47    int second = (timecode >>  8) & 0xff;
48    int minute = (timecode >> 16) & 0xff;
49    int hour   = (timecode >> 24) & 0x1f;
50    int drop   = (timecode >> 29) & 1;
51    // bit 30: color_frame, unused
52    // ignore invalid time code
53    if (timecode >> 31)
54        return 0;
55    snprintf(tmp, sizeof(tmp), "%02d:%02d:%02d%c%02d",
56        hour, minute, second, drop ? ';' : ':', frame);
57    return av_dict_set(pm, key, tmp, 0);
58 }
59 
60 /**
61  * @brief parses a packet header, extracting type and length
62  * @param pb AVIOContext to read header from
63  * @param type detected packet type is stored here
64  * @param length detected packet length, excluding header is stored here
65  * @return 0 if header not found or contains invalid data, 1 otherwise
66  */
parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length)67 static int parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length) {
68     if (avio_rb32(pb))
69         return 0;
70     if (avio_r8(pb) != 1)
71         return 0;
72     *type = avio_r8(pb);
73     *length = avio_rb32(pb);
74     if ((*length >> 24) || *length < 16)
75         return 0;
76     *length -= 16;
77     if (avio_rb32(pb))
78         return 0;
79     if (avio_r8(pb) != 0xe1)
80         return 0;
81     if (avio_r8(pb) != 0xe2)
82         return 0;
83     return 1;
84 }
85 
86 /**
87  * @brief check if file starts with a PKT_MAP header
88  */
gxf_probe(const AVProbeData *p)89 static int gxf_probe(const AVProbeData *p) {
90     static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet
91     static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};
92     if (!memcmp(p->buf, startcode, sizeof(startcode)) &&
93         !memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))
94         return AVPROBE_SCORE_MAX;
95     return 0;
96 }
97 
98 /**
99  * @brief gets the stream index for the track with the specified id, creates new
100  *        stream if not found
101  * @param id     id of stream to find / add
102  * @param format stream format identifier
103  */
get_sindex(AVFormatContext *s, int id, int format)104 static int get_sindex(AVFormatContext *s, int id, int format) {
105     int i;
106     AVStream *st = NULL;
107     FFStream *sti;
108     i = ff_find_stream_index(s, id);
109     if (i >= 0)
110         return i;
111     st = avformat_new_stream(s, NULL);
112     if (!st)
113         return AVERROR(ENOMEM);
114     sti = ffstream(st);
115     st->id = id;
116     switch (format) {
117         case 3:
118         case 4:
119             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
120             st->codecpar->codec_id = AV_CODEC_ID_MJPEG;
121             break;
122         case 13:
123         case 14:
124         case 15:
125         case 16:
126         case 25:
127             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
128             st->codecpar->codec_id = AV_CODEC_ID_DVVIDEO;
129             break;
130         case 11:
131         case 12:
132         case 20:
133             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
134             st->codecpar->codec_id = AV_CODEC_ID_MPEG2VIDEO;
135             sti->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
136             break;
137         case 22:
138         case 23:
139             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
140             st->codecpar->codec_id = AV_CODEC_ID_MPEG1VIDEO;
141             sti->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
142             break;
143         case 9:
144             st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
145             st->codecpar->codec_id = AV_CODEC_ID_PCM_S24LE;
146             st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
147             st->codecpar->sample_rate = 48000;
148             st->codecpar->bit_rate = 3 * 1 * 48000 * 8;
149             st->codecpar->block_align = 3 * 1;
150             st->codecpar->bits_per_coded_sample = 24;
151             break;
152         case 10:
153             st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
154             st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
155             st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
156             st->codecpar->sample_rate = 48000;
157             st->codecpar->bit_rate = 2 * 1 * 48000 * 8;
158             st->codecpar->block_align = 2 * 1;
159             st->codecpar->bits_per_coded_sample = 16;
160             break;
161         case 17:
162             st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
163             st->codecpar->codec_id = AV_CODEC_ID_AC3;
164             st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
165             st->codecpar->sample_rate = 48000;
166             break;
167         case 26: /* AVCi50 / AVCi100 (AVC Intra) */
168         case 29: /* AVCHD */
169             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
170             st->codecpar->codec_id = AV_CODEC_ID_H264;
171             sti->need_parsing = AVSTREAM_PARSE_HEADERS;
172             break;
173         // timecode tracks:
174         case 7:
175         case 8:
176         case 24:
177             st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
178             st->codecpar->codec_id = AV_CODEC_ID_NONE;
179             break;
180         case 30:
181             st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
182             st->codecpar->codec_id = AV_CODEC_ID_DNXHD;
183             break;
184         default:
185             st->codecpar->codec_type = AVMEDIA_TYPE_UNKNOWN;
186             st->codecpar->codec_id = AV_CODEC_ID_NONE;
187             break;
188     }
189     return s->nb_streams - 1;
190 }
191 
192 /**
193  * @brief filters out interesting tags from material information.
194  * @param len length of tag section, will be adjusted to contain remaining bytes
195  * @param si struct to store collected information into
196  */
gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si)197 static void gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
198     si->first_field = AV_NOPTS_VALUE;
199     si->last_field = AV_NOPTS_VALUE;
200     while (*len >= 2) {
201         GXFMatTag tag = avio_r8(pb);
202         int tlen = avio_r8(pb);
203         *len -= 2;
204         if (tlen > *len)
205             return;
206         *len -= tlen;
207         if (tlen == 4) {
208             uint32_t value = avio_rb32(pb);
209             if (tag == MAT_FIRST_FIELD)
210                 si->first_field = value;
211             else if (tag == MAT_LAST_FIELD)
212                 si->last_field = value;
213         } else
214             avio_skip(pb, tlen);
215     }
216 }
217 
218 static const AVRational frame_rate_tab[] = {
219     {   60,    1},
220     {60000, 1001},
221     {   50,    1},
222     {   30,    1},
223     {30000, 1001},
224     {   25,    1},
225     {   24,    1},
226     {24000, 1001},
227     {    0,    0},
228 };
229 
230 /**
231  * @brief convert fps tag value to AVRational fps
232  * @param fps fps value from tag
233  * @return fps as AVRational, or 0 / 0 if unknown
234  */
fps_tag2avr(int32_t fps)235 static AVRational fps_tag2avr(int32_t fps) {
236     if (fps < 1 || fps > 9) fps = 9;
237     return frame_rate_tab[fps - 1];
238 }
239 
240 /**
241  * @brief convert UMF attributes flags to AVRational fps
242  * @param flags UMF flags to convert
243  * @return fps as AVRational, or 0 / 0 if unknown
244  */
fps_umf2avr(uint32_t flags)245 static AVRational fps_umf2avr(uint32_t flags) {
246     static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
247         {25, 1}, {30000, 1001}};
248     int idx =  av_log2((flags & 0x7c0) >> 6);
249     return map[idx];
250 }
251 
252 /**
253  * @brief filters out interesting tags from track information.
254  * @param len length of tag section, will be adjusted to contain remaining bytes
255  * @param si struct to store collected information into
256  */
gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si)257 static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
258     si->frames_per_second = (AVRational){0, 0};
259     si->fields_per_frame = 0;
260     si->track_aux_data = 0x80000000;
261     while (*len >= 2) {
262         GXFTrackTag tag = avio_r8(pb);
263         int tlen = avio_r8(pb);
264         *len -= 2;
265         if (tlen > *len)
266             return;
267         *len -= tlen;
268         if (tlen == 4) {
269             uint32_t value = avio_rb32(pb);
270             if (tag == TRACK_FPS)
271                 si->frames_per_second = fps_tag2avr(value);
272             else if (tag == TRACK_FPF && (value == 1 || value == 2))
273                 si->fields_per_frame = value;
274         } else if (tlen == 8 && tag == TRACK_AUX)
275             si->track_aux_data = avio_rl64(pb);
276         else
277             avio_skip(pb, tlen);
278     }
279 }
280 
281 /**
282  * @brief read index from FLT packet into stream 0 av_index
283  */
gxf_read_index(AVFormatContext *s, int pkt_len)284 static void gxf_read_index(AVFormatContext *s, int pkt_len) {
285     AVIOContext *pb = s->pb;
286     AVStream *st;
287     uint32_t fields_per_map, map_cnt;
288     int i;
289     if (pkt_len < 8)
290         return;
291     fields_per_map = avio_rl32(pb);
292     map_cnt = avio_rl32(pb);
293     pkt_len -= 8;
294     if ((s->flags & AVFMT_FLAG_IGNIDX) || !s->streams) {
295         avio_skip(pb, pkt_len);
296         return;
297     }
298     st = s->streams[0];
299     if (map_cnt > 1000) {
300         av_log(s, AV_LOG_ERROR,
301                "too many index entries %"PRIu32" (%"PRIx32")\n",
302                map_cnt, map_cnt);
303         map_cnt = 1000;
304     }
305     if (pkt_len < 4 * map_cnt) {
306         av_log(s, AV_LOG_ERROR, "invalid index length\n");
307         avio_skip(pb, pkt_len);
308         return;
309     }
310     pkt_len -= 4 * map_cnt;
311     av_add_index_entry(st, 0, 0, 0, 0, 0);
312     for (i = 0; i < map_cnt; i++)
313         av_add_index_entry(st, (uint64_t)avio_rl32(pb) * 1024,
314                            i * (uint64_t)fields_per_map + 1, 0, 0, 0);
315     avio_skip(pb, pkt_len);
316 }
317 
gxf_header(AVFormatContext *s)318 static int gxf_header(AVFormatContext *s) {
319     AVIOContext *pb = s->pb;
320     GXFPktType pkt_type;
321     int map_len;
322     int len;
323     AVRational main_timebase = {0, 0};
324     struct gxf_stream_info *si = s->priv_data;
325     int i;
326     if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
327         av_log(s, AV_LOG_ERROR, "map packet not found\n");
328         return 0;
329     }
330     map_len -= 2;
331     if (avio_r8(pb) != 0x0e0 || avio_r8(pb) != 0xff) {
332         av_log(s, AV_LOG_ERROR, "unknown version or invalid map preamble\n");
333         return 0;
334     }
335     map_len -= 2;
336     len = avio_rb16(pb); // length of material data section
337     if (len > map_len) {
338         av_log(s, AV_LOG_ERROR, "material data longer than map data\n");
339         return 0;
340     }
341     map_len -= len;
342     gxf_material_tags(pb, &len, si);
343     avio_skip(pb, len);
344     map_len -= 2;
345     len = avio_rb16(pb); // length of track description
346     if (len > map_len) {
347         av_log(s, AV_LOG_ERROR, "track description longer than map data\n");
348         return 0;
349     }
350     map_len -= len;
351     while (len > 0) {
352         int track_type, track_id, track_len;
353         AVStream *st;
354         int idx;
355         len -= 4;
356         track_type = avio_r8(pb);
357         track_id = avio_r8(pb);
358         track_len = avio_rb16(pb);
359         len -= track_len;
360         if (!(track_type & 0x80)) {
361            av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);
362            continue;
363         }
364         track_type &= 0x7f;
365         if ((track_id & 0xc0) != 0xc0) {
366            av_log(s, AV_LOG_ERROR, "invalid track id %x\n", track_id);
367            continue;
368         }
369         track_id &= 0x3f;
370         gxf_track_tags(pb, &track_len, si);
371         // check for timecode tracks
372         if (track_type == 7 || track_type == 8 || track_type == 24) {
373             add_timecode_metadata(&s->metadata, "timecode",
374                                   si->track_aux_data & 0xffffffff,
375                                   si->fields_per_frame);
376 
377         }
378         avio_skip(pb, track_len);
379 
380         idx = get_sindex(s, track_id, track_type);
381         if (idx < 0) continue;
382         st = s->streams[idx];
383         if (!main_timebase.num || !main_timebase.den) {
384             main_timebase.num = si->frames_per_second.den;
385             main_timebase.den = si->frames_per_second.num * 2;
386         }
387         st->start_time = si->first_field;
388         if (si->first_field != AV_NOPTS_VALUE && si->last_field != AV_NOPTS_VALUE)
389             st->duration = si->last_field - si->first_field;
390     }
391     if (len < 0)
392         av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");
393     if (map_len)
394         avio_skip(pb, map_len);
395     if (!parse_packet_header(pb, &pkt_type, &len)) {
396         av_log(s, AV_LOG_ERROR, "sync lost in header\n");
397         return -1;
398     }
399     if (pkt_type == PKT_FLT) {
400         gxf_read_index(s, len);
401         if (!parse_packet_header(pb, &pkt_type, &len)) {
402             av_log(s, AV_LOG_ERROR, "sync lost in header\n");
403             return -1;
404         }
405     }
406     if (pkt_type == PKT_UMF) {
407         if (len >= 0x39) {
408             AVRational fps;
409             len -= 0x39;
410             avio_skip(pb, 5); // preamble
411             avio_skip(pb, 0x30); // payload description
412             fps = fps_umf2avr(avio_rl32(pb));
413             if (!main_timebase.num || !main_timebase.den) {
414                 av_log(s, AV_LOG_WARNING, "No FPS track tag, using UMF fps tag."
415                                           " This might give wrong results.\n");
416                 // this may not always be correct, but simply the best we can get
417                 main_timebase.num = fps.den;
418                 main_timebase.den = fps.num * 2;
419             }
420 
421             if (len >= 0x18) {
422                 len -= 0x18;
423                 avio_skip(pb, 0x10);
424                 add_timecode_metadata(&s->metadata, "timecode_at_mark_in",
425                                       avio_rl32(pb), si->fields_per_frame);
426                 add_timecode_metadata(&s->metadata, "timecode_at_mark_out",
427                                       avio_rl32(pb), si->fields_per_frame);
428             }
429         } else
430             av_log(s, AV_LOG_INFO, "UMF packet too short\n");
431     } else
432         av_log(s, AV_LOG_INFO, "UMF packet missing\n");
433     avio_skip(pb, len);
434     // set a fallback value, 60000/1001 is specified for audio-only files
435     // so use that regardless of why we do not know the video frame rate.
436     if (!main_timebase.num || !main_timebase.den)
437         main_timebase = (AVRational){1001, 60000};
438     for (i = 0; i < s->nb_streams; i++) {
439         AVStream *st = s->streams[i];
440         avpriv_set_pts_info(st, 32, main_timebase.num, main_timebase.den);
441     }
442     return 0;
443 }
444 
445 #define READ_ONE() \
446     { \
447         if (!max_interval-- || avio_feof(pb)) \
448             goto out; \
449         tmp = tmp << 8 | avio_r8(pb); \
450     }
451 
452 /**
453  * @brief resync the stream on the next media packet with specified properties
454  * @param max_interval how many bytes to search for matching packet at most
455  * @param track track id the media packet must belong to, -1 for any
456  * @param timestamp minimum timestamp (== field number) the packet must have, -1 for any
457  * @return timestamp of packet found
458  */
gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp)459 static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
460     uint32_t tmp;
461     uint64_t last_pos;
462     uint64_t last_found_pos = 0;
463     int cur_track;
464     int64_t cur_timestamp = AV_NOPTS_VALUE;
465     int len;
466     AVIOContext *pb = s->pb;
467     GXFPktType type;
468     tmp = avio_rb32(pb);
469 start:
470     while (tmp)
471         READ_ONE();
472     READ_ONE();
473     if (tmp != 1)
474         goto start;
475     last_pos = avio_tell(pb);
476     if (avio_seek(pb, -5, SEEK_CUR) < 0)
477         goto out;
478     if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
479         if (avio_seek(pb, last_pos, SEEK_SET) < 0)
480             goto out;
481         goto start;
482     }
483     avio_r8(pb);
484     cur_track = avio_r8(pb);
485     cur_timestamp = avio_rb32(pb);
486     last_found_pos = avio_tell(pb) - 16 - 6;
487     if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
488         if (avio_seek(pb, last_pos, SEEK_SET) >= 0)
489             goto start;
490     }
491 out:
492     if (last_found_pos)
493         avio_seek(pb, last_found_pos, SEEK_SET);
494     return cur_timestamp;
495 }
496 
gxf_packet(AVFormatContext *s, AVPacket *pkt)497 static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
498     AVIOContext *pb = s->pb;
499     GXFPktType pkt_type;
500     int pkt_len;
501     struct gxf_stream_info *si = s->priv_data;
502 
503     while (!pb->eof_reached) {
504         AVStream *st;
505         int track_type, track_id, ret;
506         int field_nr, field_info, skip = 0;
507         int stream_index;
508         if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
509             if (!avio_feof(pb))
510                 av_log(s, AV_LOG_ERROR, "sync lost\n");
511             return -1;
512         }
513         if (pkt_type == PKT_FLT) {
514             gxf_read_index(s, pkt_len);
515             continue;
516         }
517         if (pkt_type != PKT_MEDIA) {
518             avio_skip(pb, pkt_len);
519             continue;
520         }
521         if (pkt_len < 16) {
522             av_log(s, AV_LOG_ERROR, "invalid media packet length\n");
523             continue;
524         }
525         pkt_len -= 16;
526         track_type = avio_r8(pb);
527         track_id = avio_r8(pb);
528         stream_index = get_sindex(s, track_id, track_type);
529         if (stream_index < 0)
530             return stream_index;
531         st = s->streams[stream_index];
532         field_nr = avio_rb32(pb);
533         field_info = avio_rb32(pb);
534         avio_rb32(pb); // "timeline" field number
535         avio_r8(pb); // flags
536         avio_r8(pb); // reserved
537         if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S24LE ||
538             st->codecpar->codec_id == AV_CODEC_ID_PCM_S16LE) {
539             int first = field_info >> 16;
540             int last  = field_info & 0xffff; // last is exclusive
541             int bps = av_get_bits_per_sample(st->codecpar->codec_id)>>3;
542             if (first <= last && last*bps <= pkt_len) {
543                 avio_skip(pb, first*bps);
544                 skip = pkt_len - last*bps;
545                 pkt_len = (last-first)*bps;
546             } else
547                 av_log(s, AV_LOG_ERROR, "invalid first and last sample values\n");
548         }
549         ret = av_get_packet(pb, pkt, pkt_len);
550         if (skip)
551             avio_skip(pb, skip);
552         pkt->stream_index = stream_index;
553         pkt->dts = field_nr;
554 
555         //set duration manually for DV or else lavf misdetects the frame rate
556         if (st->codecpar->codec_id == AV_CODEC_ID_DVVIDEO)
557             pkt->duration = si->fields_per_frame;
558 
559         return ret;
560     }
561     return AVERROR_EOF;
562 }
563 
gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)564 static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
565     int64_t res = 0;
566     uint64_t pos;
567     uint64_t maxlen = 100 * 1024 * 1024;
568     AVStream *st = s->streams[0];
569     FFStream *const sti = ffstream(st);
570     int64_t start_time = s->streams[stream_index]->start_time;
571     int64_t found;
572     int idx;
573     if (timestamp < start_time) timestamp = start_time;
574     idx = av_index_search_timestamp(st, timestamp - start_time,
575                                     AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);
576     if (idx < 0)
577         return -1;
578     pos = sti->index_entries[idx].pos;
579     if (idx < sti->nb_index_entries - 2)
580         maxlen = sti->index_entries[idx + 2].pos - pos;
581     maxlen = FFMAX(maxlen, 200 * 1024);
582     res = avio_seek(s->pb, pos, SEEK_SET);
583     if (res < 0)
584         return res;
585     found = gxf_resync_media(s, maxlen, -1, timestamp);
586     if (FFABS(found - timestamp) > 4)
587         return -1;
588     return 0;
589 }
590 
gxf_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos, int64_t pos_limit)591 static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
592                                   int64_t *pos, int64_t pos_limit) {
593     AVIOContext *pb = s->pb;
594     int64_t res;
595     if (avio_seek(pb, *pos, SEEK_SET) < 0)
596         return AV_NOPTS_VALUE;
597     res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
598     *pos = avio_tell(pb);
599     return res;
600 }
601 
602 const AVInputFormat ff_gxf_demuxer = {
603     .name           = "gxf",
604     .long_name      = NULL_IF_CONFIG_SMALL("GXF (General eXchange Format)"),
605     .priv_data_size = sizeof(struct gxf_stream_info),
606     .read_probe     = gxf_probe,
607     .read_header    = gxf_header,
608     .read_packet    = gxf_packet,
609     .read_seek      = gxf_seek,
610     .read_timestamp = gxf_read_timestamp,
611 };
612