libavformat/dhav.c - third_party/ffmpeg - Git at Google

 /*
  * DHAV demuxer
  *
  * Copyright (c) 2018 Paul B Mahol
  *
  * 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/parseutils.h"
 #include "avio_internal.h"
 #include "avformat.h"
 #include "internal.h"

 typedef struct DHAVContext {
     unsigned type;
     unsigned subtype;
     unsigned channel;
     unsigned frame_subnumber;
     unsigned frame_number;
     unsigned date;
     unsigned timestamp;
     int width, height;
     int video_codec;
     int frame_rate;
     int audio_channels;
     int audio_codec;
     int sample_rate;

     int video_stream_index;
     int audio_stream_index;
 } DHAVContext;

 typedef struct DHAVStream {
     int64_t last_timestamp;
     int64_t pts;
 } DHAVStream;

 static int dhav_probe(const AVProbeData *p)
 {
     if (!memcmp(p->buf, "DAHUA", 5))
         return AVPROBE_SCORE_MAX;

     if (memcmp(p->buf, "DHAV", 4))
         return 0;

     if (p->buf[4] == 0xf0 ||
         p->buf[4] == 0xf1 ||
         p->buf[4] == 0xfc ||
         p->buf[4] == 0xfd)
         return AVPROBE_SCORE_MAX;
     return 0;
 }

 static int dhav_read_header(AVFormatContext *s)
 {
     DHAVContext *dhav = s->priv_data;
     uint8_t signature[5];

     ffio_ensure_seekback(s->pb, 5);
     avio_read(s->pb, signature, sizeof(signature));
     if (!memcmp(signature, "DAHUA", 5))
         avio_skip(s->pb, 0x400 - 5);
     else
         avio_seek(s->pb, -5, SEEK_CUR);

     s->ctx_flags |= AVFMTCTX_NOHEADER;
     dhav->video_stream_index = -1;
     dhav->audio_stream_index = -1;

     return 0;
 }

 static int64_t get_pts(AVFormatContext *s, DHAVStream *st)
 {
     DHAVContext *dhav = s->priv_data;
     /*
     int year, month, day, hour, min, sec;
     struct tm timeinfo;

     sec   =   dhav->date        & 0x3F;
     min   =  (dhav->date >>  6) & 0x3F;
     hour  =  (dhav->date >> 12) & 0x1F;
     day   =  (dhav->date >> 17) & 0x1F;
     month =  (dhav->date >> 22) & 0x0F;
     year  = ((dhav->date >> 26) & 0x3F) + 2000;

     timeinfo.tm_year = year - 1900;
     timeinfo.tm_mon  = month - 1;
     timeinfo.tm_mday = day;
     timeinfo.tm_hour = hour;
     timeinfo.tm_min  = min;
     timeinfo.tm_sec  = sec;*/

     if (st->last_timestamp == AV_NOPTS_VALUE) {
         st->last_timestamp = dhav->timestamp;
     }

     if (st->last_timestamp <= dhav->timestamp) {
         st->pts += dhav->timestamp - st->last_timestamp;
     } else {
         st->pts += 65535 + dhav->timestamp - st->last_timestamp;
     }

     st->last_timestamp = dhav->timestamp;

     return st->pts;
 }

 static const uint32_t sample_rates[] = {
     8000, 4000, 8000, 11025, 16000,
     20000, 22050, 32000, 44100, 48000,
     96000, 192000, 64000,
 };

 static int parse_ext(AVFormatContext *s, int length)
 {
     DHAVContext *dhav = s->priv_data;
     int index;

     while (length > 0) {
         int type = avio_r8(s->pb);

         switch (type) {
         case 0x80:
             avio_skip(s->pb, 1);
             dhav->width  = 8 * avio_r8(s->pb);
             dhav->height = 8 * avio_r8(s->pb);
             length -= 4;
             break;
         case 0x81:
             avio_skip(s->pb, 1);
             dhav->video_codec = avio_r8(s->pb);
             dhav->frame_rate = avio_r8(s->pb);
             length -= 4;
             break;
         case 0x82:
             avio_skip(s->pb, 3);
             dhav->width  = avio_rl16(s->pb);
             dhav->height = avio_rl16(s->pb);
             length -= 8;
             break;
         case 0x83:
             dhav->audio_channels = avio_r8(s->pb);
             dhav->audio_codec = avio_r8(s->pb);
             index = avio_r8(s->pb);
             if (index < FF_ARRAY_ELEMS(sample_rates)) {
                 dhav->sample_rate = sample_rates[index];
             } else {
                 dhav->sample_rate = 8000;
             }
             length -= 4;
             break;
         case 0x88:
             avio_skip(s->pb, 7);
             length -= 8;
             break;
         case 0x8c:
             avio_skip(s->pb, 1);
             dhav->audio_channels = avio_r8(s->pb);
             dhav->audio_codec = avio_r8(s->pb);
             index = avio_r8(s->pb);
             if (index < FF_ARRAY_ELEMS(sample_rates)) {
                 dhav->sample_rate = sample_rates[index];
             } else {
                 dhav->sample_rate = 8000;
             }
             avio_skip(s->pb, 3);
             length -= 8;
             break;
         case 0x91:
         case 0x92:
         case 0x93:
         case 0x95:
         case 0x9a:
         case 0x9b: // sample aspect ratio
         case 0xb3:
             avio_skip(s->pb, 7);
             length -= 8;
             break;
         case 0x84:
         case 0x85:
         case 0x8b:
         case 0x94:
         case 0x96:
         case 0xa0:
         case 0xb2:
         case 0xb4:
             avio_skip(s->pb, 3);
             length -= 4;
             break;
         default:
             av_log(s, AV_LOG_INFO, "Unknown type: %X, skipping rest of header.\n", type);
             avio_skip(s->pb, length - 1);
             length = 0;
         }
     }

     return 0;
 }

 static int read_chunk(AVFormatContext *s)
 {
     DHAVContext *dhav = s->priv_data;
     unsigned frame_length, ext_length;
     int64_t start, end;
     int ret;

     start = avio_tell(s->pb);

     if (avio_feof(s->pb))
         return AVERROR_EOF;

     if (avio_rl32(s->pb) != MKTAG('D','H','A','V'))
         return AVERROR_INVALIDDATA;

     dhav->type = avio_r8(s->pb);
     dhav->subtype = avio_r8(s->pb);
     dhav->channel = avio_r8(s->pb);
     dhav->frame_subnumber = avio_r8(s->pb);
     dhav->frame_number = avio_rl32(s->pb);
     frame_length = avio_rl32(s->pb);

     if (frame_length < 24)
         return AVERROR_INVALIDDATA;
     if (dhav->type == 0xf1) {
         avio_skip(s->pb, frame_length - 16);
         return 0;
     }

     dhav->date = avio_rl32(s->pb);
     dhav->timestamp = avio_rl16(s->pb);
     ext_length = avio_r8(s->pb);
     avio_skip(s->pb, 1); // checksum

     ret = parse_ext(s, ext_length);
     if (ret < 0)
         return ret;

     end = avio_tell(s->pb);

     return frame_length - 8 - (end - start);
 }

 static int dhav_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DHAVContext *dhav = s->priv_data;
     int64_t start;
     int ret;

     start = avio_tell(s->pb);

     while ((ret = read_chunk(s)) == 0)
         ;

     if (ret < 0)
         return ret;

     if (dhav->type == 0xfd && dhav->video_stream_index == -1) {
         AVStream *st = avformat_new_stream(s, NULL);
         DHAVStream *dst;

         if (!st)
             return AVERROR(ENOMEM);

         st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
         switch (dhav->video_codec) {
         case 0x1: st->codecpar->codec_id = AV_CODEC_ID_MPEG4; break;
         case 0x3: st->codecpar->codec_id = AV_CODEC_ID_MJPEG; break;
         case 0x2:
         case 0x4:
         case 0x8: st->codecpar->codec_id = AV_CODEC_ID_H264;  break;
         case 0xc: st->codecpar->codec_id = AV_CODEC_ID_HEVC;  break;
         default: avpriv_request_sample(s, "Unknown video codec %X\n", dhav->video_codec);
         }
         st->codecpar->width      = dhav->width;
         st->codecpar->height     = dhav->height;
         st->avg_frame_rate.num   = dhav->frame_rate;
         st->avg_frame_rate.den   = 1;
         st->priv_data = dst = av_mallocz(sizeof(DHAVStream));
         if (!st->priv_data)
             return AVERROR(ENOMEM);
         dst->last_timestamp = AV_NOPTS_VALUE;
         dhav->video_stream_index = st->index;

         avpriv_set_pts_info(st, 64, 1, 1000);
     } else if (dhav->type == 0xf0 && dhav->audio_stream_index == -1) {
         AVStream *st = avformat_new_stream(s, NULL);
         DHAVStream *dst;

         if (!st)
             return AVERROR(ENOMEM);

         st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
         switch (dhav->audio_codec) {
         case 0x07: st->codecpar->codec_id = AV_CODEC_ID_PCM_S8;    break;
         case 0x0c: st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE; break;
         case 0x10: st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE; break;
         case 0x0a: st->codecpar->codec_id = AV_CODEC_ID_PCM_MULAW; break;
         case 0x16: st->codecpar->codec_id = AV_CODEC_ID_PCM_MULAW; break;
         case 0x0e: st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW;  break;
         case 0x1a: st->codecpar->codec_id = AV_CODEC_ID_AAC;       break;
         case 0x1f: st->codecpar->codec_id = AV_CODEC_ID_MP2;       break;
         case 0x21: st->codecpar->codec_id = AV_CODEC_ID_MP3;       break;
         case 0x0d: st->codecpar->codec_id = AV_CODEC_ID_ADPCM_MS;  break;
         default: avpriv_request_sample(s, "Unknown audio codec %X\n", dhav->audio_codec);
         }
         st->codecpar->channels    = dhav->audio_channels;
         st->codecpar->sample_rate = dhav->sample_rate;
         st->priv_data = dst = av_mallocz(sizeof(DHAVStream));
         if (!st->priv_data)
             return AVERROR(ENOMEM);
         dst->last_timestamp = AV_NOPTS_VALUE;
         dhav->audio_stream_index  = st->index;

         avpriv_set_pts_info(st, 64, 1, 1000);
     }

     ret = av_get_packet(s->pb, pkt, ret);
     if (ret < 0)
         return ret;
     pkt->stream_index = dhav->type == 0xf0 ? dhav->audio_stream_index : dhav->video_stream_index;
     if (dhav->type != 0xfc)
         pkt->flags   |= AV_PKT_FLAG_KEY;
     if (pkt->stream_index >= 0)
         pkt->pts = get_pts(s, s->streams[pkt->stream_index]->priv_data);
     pkt->duration = 1;
     pkt->pos = start;
     if (avio_rl32(s->pb) != MKTAG('d','h','a','v'))
         return AVERROR_INVALIDDATA;
     avio_skip(s->pb, 4);

     return ret;
 }

 static int dhav_read_seek(AVFormatContext *s, int stream_index,
                           int64_t timestamp, int flags)
 {
     AVStream *st = s->streams[stream_index];
     int index = av_index_search_timestamp(st, timestamp, flags);
     int64_t pts;

     if (index < 0)
         return -1;
     if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)
         return -1;

     pts = st->index_entries[index].timestamp;

     for (int n = 0; n < s->nb_streams; n++) {
         AVStream *st = s->streams[n];
         DHAVStream *dst = st->priv_data;

         dst->pts = pts;
         dst->last_timestamp = AV_NOPTS_VALUE;
     }

     return 0;
 }

 AVInputFormat ff_dhav_demuxer = {
     .name           = "dhav",
     .long_name      = NULL_IF_CONFIG_SMALL("Video DAV"),
     .priv_data_size = sizeof(DHAVContext),
     .read_probe     = dhav_probe,
     .read_header    = dhav_read_header,
     .read_packet    = dhav_read_packet,
     .read_seek      = dhav_read_seek,
     .extensions     = "dav",
     .flags          = AVFMT_GENERIC_INDEX | AVFMT_NO_BYTE_SEEK,
 };
	/*
	* DHAV demuxer
	*
	* Copyright (c) 2018 Paul B Mahol
	*
	* 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/parseutils.h"
	#include "avio_internal.h"
	#include "avformat.h"
	#include "internal.h"

	typedef struct DHAVContext {
	unsigned type;
	unsigned subtype;
	unsigned channel;
	unsigned frame_subnumber;
	unsigned frame_number;
	unsigned date;
	unsigned timestamp;
	int width, height;
	int video_codec;
	int frame_rate;
	int audio_channels;
	int audio_codec;
	int sample_rate;

	int video_stream_index;
	int audio_stream_index;
	} DHAVContext;

	typedef struct DHAVStream {
	int64_t last_timestamp;
	int64_t pts;
	} DHAVStream;

	static int dhav_probe(const AVProbeData *p)
	{
	if (!memcmp(p->buf, "DAHUA", 5))
	return AVPROBE_SCORE_MAX;

	if (memcmp(p->buf, "DHAV", 4))
	return 0;

	if (p->buf[4] == 0xf0 \|\|
	p->buf[4] == 0xf1 \|\|
	p->buf[4] == 0xfc \|\|
	p->buf[4] == 0xfd)
	return AVPROBE_SCORE_MAX;
	return 0;
	}

	static int dhav_read_header(AVFormatContext *s)
	{
	DHAVContext *dhav = s->priv_data;
	uint8_t signature[5];

	ffio_ensure_seekback(s->pb, 5);
	avio_read(s->pb, signature, sizeof(signature));
	if (!memcmp(signature, "DAHUA", 5))
	avio_skip(s->pb, 0x400 - 5);
	else
	avio_seek(s->pb, -5, SEEK_CUR);

	s->ctx_flags \|= AVFMTCTX_NOHEADER;
	dhav->video_stream_index = -1;
	dhav->audio_stream_index = -1;

	return 0;
	}

	static int64_t get_pts(AVFormatContext s, DHAVStream st)
	{
	DHAVContext *dhav = s->priv_data;
	/*
	int year, month, day, hour, min, sec;
	struct tm timeinfo;

	sec = dhav->date & 0x3F;
	min = (dhav->date >> 6) & 0x3F;
	hour = (dhav->date >> 12) & 0x1F;
	day = (dhav->date >> 17) & 0x1F;
	month = (dhav->date >> 22) & 0x0F;
	year = ((dhav->date >> 26) & 0x3F) + 2000;

	timeinfo.tm_year = year - 1900;
	timeinfo.tm_mon = month - 1;
	timeinfo.tm_mday = day;
	timeinfo.tm_hour = hour;
	timeinfo.tm_min = min;
	timeinfo.tm_sec = sec;*/

	if (st->last_timestamp == AV_NOPTS_VALUE) {
	st->last_timestamp = dhav->timestamp;
	}

	if (st->last_timestamp <= dhav->timestamp) {
	st->pts += dhav->timestamp - st->last_timestamp;
	} else {
	st->pts += 65535 + dhav->timestamp - st->last_timestamp;
	}

	st->last_timestamp = dhav->timestamp;

	return st->pts;
	}

	static const uint32_t sample_rates[] = {
	8000, 4000, 8000, 11025, 16000,
	20000, 22050, 32000, 44100, 48000,
	96000, 192000, 64000,
	};

	static int parse_ext(AVFormatContext *s, int length)
	{
	DHAVContext *dhav = s->priv_data;
	int index;

	while (length > 0) {
	int type = avio_r8(s->pb);

	switch (type) {
	case 0x80:
	avio_skip(s->pb, 1);
	dhav->width = 8 * avio_r8(s->pb);
	dhav->height = 8 * avio_r8(s->pb);
	length -= 4;
	break;
	case 0x81:
	avio_skip(s->pb, 1);
	dhav->video_codec = avio_r8(s->pb);
	dhav->frame_rate = avio_r8(s->pb);
	length -= 4;
	break;
	case 0x82:
	avio_skip(s->pb, 3);
	dhav->width = avio_rl16(s->pb);
	dhav->height = avio_rl16(s->pb);
	length -= 8;
	break;
	case 0x83:
	dhav->audio_channels = avio_r8(s->pb);
	dhav->audio_codec = avio_r8(s->pb);
	index = avio_r8(s->pb);
	if (index < FF_ARRAY_ELEMS(sample_rates)) {
	dhav->sample_rate = sample_rates[index];
	} else {
	dhav->sample_rate = 8000;
	}
	length -= 4;
	break;
	case 0x88:
	avio_skip(s->pb, 7);
	length -= 8;
	break;
	case 0x8c:
	avio_skip(s->pb, 1);
	dhav->audio_channels = avio_r8(s->pb);
	dhav->audio_codec = avio_r8(s->pb);
	index = avio_r8(s->pb);
	if (index < FF_ARRAY_ELEMS(sample_rates)) {
	dhav->sample_rate = sample_rates[index];
	} else {
	dhav->sample_rate = 8000;
	}
	avio_skip(s->pb, 3);
	length -= 8;
	break;
	case 0x91:
	case 0x92:
	case 0x93:
	case 0x95:
	case 0x9a:
	case 0x9b: // sample aspect ratio
	case 0xb3:
	avio_skip(s->pb, 7);
	length -= 8;
	break;
	case 0x84:
	case 0x85:
	case 0x8b:
	case 0x94:
	case 0x96:
	case 0xa0:
	case 0xb2:
	case 0xb4:
	avio_skip(s->pb, 3);
	length -= 4;
	break;
	default:
	av_log(s, AV_LOG_INFO, "Unknown type: %X, skipping rest of header.\n", type);
	avio_skip(s->pb, length - 1);
	length = 0;
	}
	}

	return 0;
	}

	static int read_chunk(AVFormatContext *s)
	{
	DHAVContext *dhav = s->priv_data;
	unsigned frame_length, ext_length;
	int64_t start, end;
	int ret;

	start = avio_tell(s->pb);

	if (avio_feof(s->pb))
	return AVERROR_EOF;

	if (avio_rl32(s->pb) != MKTAG('D','H','A','V'))
	return AVERROR_INVALIDDATA;

	dhav->type = avio_r8(s->pb);
	dhav->subtype = avio_r8(s->pb);
	dhav->channel = avio_r8(s->pb);
	dhav->frame_subnumber = avio_r8(s->pb);
	dhav->frame_number = avio_rl32(s->pb);
	frame_length = avio_rl32(s->pb);

	if (frame_length < 24)
	return AVERROR_INVALIDDATA;
	if (dhav->type == 0xf1) {
	avio_skip(s->pb, frame_length - 16);
	return 0;
	}

	dhav->date = avio_rl32(s->pb);
	dhav->timestamp = avio_rl16(s->pb);
	ext_length = avio_r8(s->pb);
	avio_skip(s->pb, 1); // checksum

	ret = parse_ext(s, ext_length);
	if (ret < 0)
	return ret;

	end = avio_tell(s->pb);

	return frame_length - 8 - (end - start);
	}

	static int dhav_read_packet(AVFormatContext s, AVPacket pkt)
	{
	DHAVContext *dhav = s->priv_data;
	int64_t start;
	int ret;

	start = avio_tell(s->pb);

	while ((ret = read_chunk(s)) == 0)
	;

	if (ret < 0)
	return ret;

	if (dhav->type == 0xfd && dhav->video_stream_index == -1) {
	AVStream *st = avformat_new_stream(s, NULL);
	DHAVStream *dst;

	if (!st)
	return AVERROR(ENOMEM);

	st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
	switch (dhav->video_codec) {
	case 0x1: st->codecpar->codec_id = AV_CODEC_ID_MPEG4; break;
	case 0x3: st->codecpar->codec_id = AV_CODEC_ID_MJPEG; break;
	case 0x2:
	case 0x4:
	case 0x8: st->codecpar->codec_id = AV_CODEC_ID_H264; break;
	case 0xc: st->codecpar->codec_id = AV_CODEC_ID_HEVC; break;
	default: avpriv_request_sample(s, "Unknown video codec %X\n", dhav->video_codec);
	}
	st->codecpar->width = dhav->width;
	st->codecpar->height = dhav->height;
	st->avg_frame_rate.num = dhav->frame_rate;
	st->avg_frame_rate.den = 1;
	st->priv_data = dst = av_mallocz(sizeof(DHAVStream));
	if (!st->priv_data)
	return AVERROR(ENOMEM);
	dst->last_timestamp = AV_NOPTS_VALUE;
	dhav->video_stream_index = st->index;

	avpriv_set_pts_info(st, 64, 1, 1000);
	} else if (dhav->type == 0xf0 && dhav->audio_stream_index == -1) {
	AVStream *st = avformat_new_stream(s, NULL);
	DHAVStream *dst;

	if (!st)
	return AVERROR(ENOMEM);

	st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
	switch (dhav->audio_codec) {
	case 0x07: st->codecpar->codec_id = AV_CODEC_ID_PCM_S8; break;
	case 0x0c: st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE; break;
	case 0x10: st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE; break;
	case 0x0a: st->codecpar->codec_id = AV_CODEC_ID_PCM_MULAW; break;
	case 0x16: st->codecpar->codec_id = AV_CODEC_ID_PCM_MULAW; break;
	case 0x0e: st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW; break;
	case 0x1a: st->codecpar->codec_id = AV_CODEC_ID_AAC; break;
	case 0x1f: st->codecpar->codec_id = AV_CODEC_ID_MP2; break;
	case 0x21: st->codecpar->codec_id = AV_CODEC_ID_MP3; break;
	case 0x0d: st->codecpar->codec_id = AV_CODEC_ID_ADPCM_MS; break;
	default: avpriv_request_sample(s, "Unknown audio codec %X\n", dhav->audio_codec);
	}
	st->codecpar->channels = dhav->audio_channels;
	st->codecpar->sample_rate = dhav->sample_rate;
	st->priv_data = dst = av_mallocz(sizeof(DHAVStream));
	if (!st->priv_data)
	return AVERROR(ENOMEM);
	dst->last_timestamp = AV_NOPTS_VALUE;
	dhav->audio_stream_index = st->index;

	avpriv_set_pts_info(st, 64, 1, 1000);
	}

	ret = av_get_packet(s->pb, pkt, ret);
	if (ret < 0)
	return ret;
	pkt->stream_index = dhav->type == 0xf0 ? dhav->audio_stream_index : dhav->video_stream_index;
	if (dhav->type != 0xfc)
	pkt->flags \|= AV_PKT_FLAG_KEY;
	if (pkt->stream_index >= 0)
	pkt->pts = get_pts(s, s->streams[pkt->stream_index]->priv_data);
	pkt->duration = 1;
	pkt->pos = start;
	if (avio_rl32(s->pb) != MKTAG('d','h','a','v'))
	return AVERROR_INVALIDDATA;
	avio_skip(s->pb, 4);

	return ret;
	}

	static int dhav_read_seek(AVFormatContext *s, int stream_index,
	int64_t timestamp, int flags)
	{
	AVStream *st = s->streams[stream_index];
	int index = av_index_search_timestamp(st, timestamp, flags);
	int64_t pts;

	if (index < 0)
	return -1;
	if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)
	return -1;

	pts = st->index_entries[index].timestamp;

	for (int n = 0; n < s->nb_streams; n++) {
	AVStream *st = s->streams[n];
	DHAVStream *dst = st->priv_data;

	dst->pts = pts;
	dst->last_timestamp = AV_NOPTS_VALUE;
	}

	return 0;
	}

	AVInputFormat ff_dhav_demuxer = {
	.name = "dhav",
	.long_name = NULL_IF_CONFIG_SMALL("Video DAV"),
	.priv_data_size = sizeof(DHAVContext),
	.read_probe = dhav_probe,
	.read_header = dhav_read_header,
	.read_packet = dhav_read_packet,
	.read_seek = dhav_read_seek,
	.extensions = "dav",
	.flags = AVFMT_GENERIC_INDEX \| AVFMT_NO_BYTE_SEEK,
	};