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pva.c
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1 /*
2  * TechnoTrend PVA (.pva) demuxer
3  * Copyright (c) 2007, 2008 Ivo van Poorten
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 "avformat.h"
23 #include "internal.h"
24 #include "mpeg.h"
25 
26 #define PVA_MAX_PAYLOAD_LENGTH 0x17f8
27 #define PVA_VIDEO_PAYLOAD 0x01
28 #define PVA_AUDIO_PAYLOAD 0x02
29 #define PVA_MAGIC (('A' << 8) + 'V')
30 
31 typedef struct {
33 } PVAContext;
34 
35 static int pva_check(const uint8_t *p) {
36  int length = AV_RB16(p + 6);
37  if (AV_RB16(p) != PVA_MAGIC || !p[2] || p[2] > 2 || p[4] != 0x55 ||
38  (p[5] & 0xe0) || length > PVA_MAX_PAYLOAD_LENGTH)
39  return -1;
40  return length + 8;
41 }
42 
43 static int pva_probe(AVProbeData * pd) {
44  const unsigned char *buf = pd->buf;
45  int len = pva_check(buf);
46 
47  if (len < 0)
48  return 0;
49 
50  if (pd->buf_size >= len + 8 &&
51  pva_check(buf + len) >= 0)
53 
54  return AVPROBE_SCORE_MAX / 4;
55 }
56 
58  AVStream *st;
59 
60  if (!(st = avformat_new_stream(s, NULL)))
61  return AVERROR(ENOMEM);
65  avpriv_set_pts_info(st, 32, 1, 90000);
66  av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
67 
68  if (!(st = avformat_new_stream(s, NULL)))
69  return AVERROR(ENOMEM);
73  avpriv_set_pts_info(st, 33, 1, 90000);
74  av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
75 
76  /* the parameters will be extracted from the compressed bitstream */
77  return 0;
78 }
79 
80 #define pva_log if (read_packet) av_log
81 
82 static int read_part_of_packet(AVFormatContext *s, int64_t *pts,
83  int *len, int *strid, int read_packet) {
84  AVIOContext *pb = s->pb;
85  PVAContext *pvactx = s->priv_data;
86  int syncword, streamid, reserved, flags, length, pts_flag;
87  int64_t pva_pts = AV_NOPTS_VALUE, startpos;
88 
89 recover:
90  startpos = avio_tell(pb);
91 
92  syncword = avio_rb16(pb);
93  streamid = avio_r8(pb);
94  avio_r8(pb); /* counter not used */
95  reserved = avio_r8(pb);
96  flags = avio_r8(pb);
97  length = avio_rb16(pb);
98 
99  pts_flag = flags & 0x10;
100 
101  if (syncword != PVA_MAGIC) {
102  pva_log(s, AV_LOG_ERROR, "invalid syncword\n");
103  return AVERROR(EIO);
104  }
105  if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) {
106  pva_log(s, AV_LOG_ERROR, "invalid streamid\n");
107  return AVERROR(EIO);
108  }
109  if (reserved != 0x55) {
110  pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n");
111  }
112  if (length > PVA_MAX_PAYLOAD_LENGTH) {
113  pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length);
114  return AVERROR(EIO);
115  }
116 
117  if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) {
118  pva_pts = avio_rb32(pb);
119  length -= 4;
120  } else if (streamid == PVA_AUDIO_PAYLOAD) {
121  /* PVA Audio Packets either start with a signaled PES packet or
122  * are a continuation of the previous PES packet. New PES packets
123  * always start at the beginning of a PVA Packet, never somewhere in
124  * the middle. */
125  if (!pvactx->continue_pes) {
126  int pes_signal, pes_header_data_length, pes_packet_length,
127  pes_flags;
128  unsigned char pes_header_data[256];
129 
130  pes_signal = avio_rb24(pb);
131  avio_r8(pb);
132  pes_packet_length = avio_rb16(pb);
133  pes_flags = avio_rb16(pb);
134  pes_header_data_length = avio_r8(pb);
135 
136  if (pes_signal != 1) {
137  pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, "
138  "trying to recover\n");
139  avio_skip(pb, length - 9);
140  if (!read_packet)
141  return AVERROR(EIO);
142  goto recover;
143  }
144 
145  avio_read(pb, pes_header_data, pes_header_data_length);
146  length -= 9 + pes_header_data_length;
147 
148  pes_packet_length -= 3 + pes_header_data_length;
149 
150  pvactx->continue_pes = pes_packet_length;
151 
152  if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20)
153  pva_pts = ff_parse_pes_pts(pes_header_data);
154  }
155 
156  pvactx->continue_pes -= length;
157 
158  if (pvactx->continue_pes < 0) {
159  pva_log(s, AV_LOG_WARNING, "audio data corruption\n");
160  pvactx->continue_pes = 0;
161  }
162  }
163 
164  if (pva_pts != AV_NOPTS_VALUE)
165  av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME);
166 
167  *pts = pva_pts;
168  *len = length;
169  *strid = streamid;
170  return 0;
171 }
172 
174  AVIOContext *pb = s->pb;
175  int64_t pva_pts;
176  int ret, length, streamid;
177 
178  if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 ||
179  (ret = av_get_packet(pb, pkt, length)) <= 0)
180  return AVERROR(EIO);
181 
182  pkt->stream_index = streamid - 1;
183  pkt->pts = pva_pts;
184 
185  return ret;
186 }
187 
188 static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index,
189  int64_t *pos, int64_t pos_limit) {
190  AVIOContext *pb = s->pb;
191  PVAContext *pvactx = s->priv_data;
192  int length, streamid;
193  int64_t res = AV_NOPTS_VALUE;
194 
195  pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit);
196 
197  while (*pos < pos_limit) {
198  res = AV_NOPTS_VALUE;
199  avio_seek(pb, *pos, SEEK_SET);
200 
201  pvactx->continue_pes = 0;
202  if (read_part_of_packet(s, &res, &length, &streamid, 0)) {
203  (*pos)++;
204  continue;
205  }
206  if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) {
207  *pos = avio_tell(pb) + length;
208  continue;
209  }
210  break;
211  }
212 
213  pvactx->continue_pes = 0;
214  return res;
215 }
216 
218  .name = "pva",
219  .long_name = NULL_IF_CONFIG_SMALL("TechnoTrend PVA"),
220  .priv_data_size = sizeof(PVAContext),
224  .read_timestamp = pva_read_timestamp,
225 };