libavformat/rtpdec_asf.c

   1 /*
   2  * Microsoft RTP/ASF support.
   3  * Copyright (c) 2008 Ronald S. Bultje
   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 /**
  23  * @file
  24  * @brief Microsoft RTP/ASF support
  25  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
  26  */
  27
  28 #include "libavutil/base64.h"
  29 #include "libavutil/avstring.h"
  30 #include "libavutil/intreadwrite.h"
  31 #include "libavutil/mem.h"
  32 #include "rtpdec_formats.h"
  33 #include "rtsp.h"
  34 #include "asf.h"
  35 #include "avio_internal.h"
  36 #include "demux.h"
  37 #include "internal.h"
  38
  39 /**
  40  * From MSDN 2.2.1.4, we learn that ASF data packets over RTP should not
  41  * contain any padding. Unfortunately, the header min/max_pktsize are not
  42  * updated (thus making min_pktsize invalid). Here, we "fix" these faulty
  43  * min_pktsize values in the ASF file header.
  44  * @return 0 on success, <0 on failure (currently -1).
  45  */
  46 static int rtp_asf_fix_header(uint8_t *buf, int len)
  47 {
  48     uint8_t *p = buf, *end = buf + len;
  49
  50     if (len < sizeof(ff_asf_guid) * 2 + 22 ||
  51         memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
  52         return -1;
  53     }
  54     p += sizeof(ff_asf_guid) + 14;
  55     do {
  56         uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
  57         int skip = 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
  58         if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
  59             if (chunksize > end - p)
  60                 return -1;
  61             p += chunksize;
  62             continue;
  63         }
  64
  65         if (end - p < 8 + skip)
  66             break;
  67         /* skip most of the file header, to min_pktsize */
  68         p += skip;
  69         if (AV_RL32(p) == AV_RL32(p + 4)) {
  70             /* and set that to zero */
  71             AV_WL32(p, 0);
  72             return 0;
  73         }
  74         break;
  75     } while (end - p >= sizeof(ff_asf_guid) + 8);
  76
  77     return -1;
  78 }
  79
  80 /**
  81  * The following code is basically a buffered AVIOContext,
  82  * with the added benefit of returning -EAGAIN (instead of 0)
  83  * on packet boundaries, such that the ASF demuxer can return
  84  * safely and resume business at the next packet.
  85  */
  86 static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
  87 {
  88     return AVERROR(EAGAIN);
  89 }
  90
  91 static void init_packetizer(FFIOContext *pb, uint8_t *buf, int len)
  92 {
  93     ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
  94
  95     /* this "fills" the buffer with its current content */
  96     pb->pub.pos     = len;
  97     pb->pub.buf_end = buf + len;
  98 }
  99
 100 int ff_wms_parse_sdp_a_line(AVFormatContext *s, const char *p)
 101 {
 102     int ret = 0;
 103     if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
 104         FFIOContext pb;
 105         RTSPState *rt = s->priv_data;
 106         AVDictionary *opts = NULL;
 107         int len = strlen(p) * 6 / 8;
 108         char *buf = av_mallocz(len);
 109         const AVInputFormat *iformat;
 110
 111         if (!buf)
 112             return AVERROR(ENOMEM);
 113         av_base64_decode(buf, p, len);
 114
 115         if (rtp_asf_fix_header(buf, len) < 0)
 116             av_log(s, AV_LOG_ERROR,
 117                    "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
 118         init_packetizer(&pb, buf, len);
 119         if (rt->asf_ctx) {
 120             avformat_close_input(&rt->asf_ctx);
 121         }
 122
 123         if (!(iformat = av_find_input_format("asf")))
 124             return AVERROR_DEMUXER_NOT_FOUND;
 125
 126         rt->asf_ctx = avformat_alloc_context();
 127         if (!rt->asf_ctx) {
 128             av_free(buf);
 129             return AVERROR(ENOMEM);
 130         }
 131         rt->asf_ctx->pb      = &pb.pub;
 132         av_dict_set(&opts, "no_resync_search", "1", 0);
 133
 134         if ((ret = ff_copy_whiteblacklists(rt->asf_ctx, s)) < 0) {
 135             av_dict_free(&opts);
 136             return ret;
 137         }
 138
 139         ret = avformat_open_input(&rt->asf_ctx, "", iformat, &opts);
 140         av_dict_free(&opts);
 141         if (ret < 0) {
 142             av_free(pb.pub.buffer);
 143             return ret;
 144         }
 145         av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
 146         rt->asf_pb_pos = avio_tell(&pb.pub);
 147         av_free(pb.pub.buffer);
 148         rt->asf_ctx->pb = NULL;
 149     }
 150     return ret;
 151 }
 152
 153 static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
 154                                  PayloadContext *asf, const char *line)
 155 {
 156     if (stream_index < 0)
 157         return 0;
 158     if (av_strstart(line, "stream:", &line)) {
 159         RTSPState *rt = s->priv_data;
 160
 161         s->streams[stream_index]->id = strtol(line, NULL, 10);
 162
 163         if (rt->asf_ctx) {
 164             int i;
 165
 166             for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
 167                 if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
 168                     avcodec_parameters_copy(s->streams[stream_index]->codecpar,
 169                                             rt->asf_ctx->streams[i]->codecpar);
 170                     ffstream(s->streams[stream_index])->need_parsing =
 171                         ffstream(rt->asf_ctx->streams[i])->need_parsing;
 172                     avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
 173                 }
 174            }
 175         }
 176     }
 177
 178     return 0;
 179 }
 180
 181 struct PayloadContext {
 182     FFIOContext pb;
 183     AVIOContext *pktbuf;
 184     uint8_t *buf;
 185 };
 186
 187 /**
 188  * @return 0 when a packet was written into /p pkt, and no more data is left;
 189  *         1 when a packet was written into /p pkt, and more packets might be left;
 190  *        <0 when not enough data was provided to return a full packet, or on error.
 191  */
 192 static int asfrtp_parse_packet(AVFormatContext *s, PayloadContext *asf,
 193                                AVStream *st, AVPacket *pkt,
 194                                uint32_t *timestamp,
 195                                const uint8_t *buf, int len, uint16_t seq,
 196                                int flags)
 197 {
 198     FFIOContext *const pb0 = &asf->pb;
 199     AVIOContext *const pb  = &pb0->pub;
 200     int res, mflags, len_off;
 201     RTSPState *rt = s->priv_data;
 202
 203     if (!rt->asf_ctx)
 204         return -1;
 205
 206     if (len > 0) {
 207         int off, out_len = 0;
 208
 209         if (len < 4)
 210             return -1;
 211
 212         av_freep(&asf->buf);
 213
 214         ffio_init_read_context(pb0, buf, len);
 215
 216         while (avio_tell(pb) + 4 < len) {
 217             int start_off = avio_tell(pb);
 218
 219             mflags = avio_r8(pb);
 220             len_off = avio_rb24(pb);
 221             if (mflags & 0x20)   /**< relative timestamp */
 222                 avio_skip(pb, 4);
 223             if (mflags & 0x10)   /**< has duration */
 224                 avio_skip(pb, 4);
 225             if (mflags & 0x8)    /**< has location ID */
 226                 avio_skip(pb, 4);
 227             off = avio_tell(pb);
 228
 229             if (!(mflags & 0x40)) {
 230                 /**
 231                  * If 0x40 is not set, the len_off field specifies an offset
 232                  * of this packet's payload data in the complete (reassembled)
 233                  * ASF packet. This is used to spread one ASF packet over
 234                  * multiple RTP packets.
 235                  */
 236                 if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
 237                     ffio_free_dyn_buf(&asf->pktbuf);
 238                 }
 239                 if (!len_off && !asf->pktbuf &&
 240                     (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
 241                     return res;
 242                 if (!asf->pktbuf)
 243                     return AVERROR(EIO);
 244
 245                 avio_write(asf->pktbuf, buf + off, len - off);
 246                 avio_skip(pb, len - off);
 247                 if (!(flags & RTP_FLAG_MARKER))
 248                     return -1;
 249                 out_len     = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
 250                 asf->pktbuf = NULL;
 251             } else {
 252                 /**
 253                  * If 0x40 is set, the len_off field specifies the length of
 254                  * the next ASF packet that can be read from this payload
 255                  * data alone. This is commonly the same as the payload size,
 256                  * but could be less in case of packet splitting (i.e.
 257                  * multiple ASF packets in one RTP packet).
 258                  */
 259
 260                 int cur_len = start_off + len_off - off;
 261                 int prev_len = out_len;
 262                 out_len += cur_len;
 263                 if (FFMIN(cur_len, len - off) < 0)
 264                     return -1;
 265                 if ((res = av_reallocp(&asf->buf, out_len)) < 0)
 266                     return res;
 267                 memcpy(asf->buf + prev_len, buf + off,
 268                        FFMIN(cur_len, len - off));
 269                 avio_skip(pb, cur_len);
 270             }
 271         }
 272
 273         init_packetizer(pb0, asf->buf, out_len);
 274         pb->pos += rt->asf_pb_pos;
 275         pb->eof_reached = 0;
 276         rt->asf_ctx->pb = pb;
 277     }
 278
 279     for (;;) {
 280         int i;
 281
 282         res = ff_read_packet(rt->asf_ctx, pkt);
 283         rt->asf_pb_pos = avio_tell(pb);
 284         if (res != 0)
 285             break;
 286         for (i = 0; i < s->nb_streams; i++) {
 287             if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
 288                 pkt->stream_index = i;
 289                 return 1; // FIXME: return 0 if last packet
 290             }
 291         }
 292         av_packet_unref(pkt);
 293     }
 294
 295     return res == 1 ? -1 : res;
 296 }
 297
 298 static void asfrtp_close_context(PayloadContext *asf)
 299 {
 300     ffio_free_dyn_buf(&asf->pktbuf);
 301     av_freep(&asf->buf);
 302 }
 303
 304 #define RTP_ASF_HANDLER(n, s, t) \
 305 const RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
 306     .enc_name         = s, \
 307     .codec_type       = t, \
 308     .codec_id         = AV_CODEC_ID_NONE, \
 309     .priv_data_size   = sizeof(PayloadContext), \
 310     .parse_sdp_a_line = asfrtp_parse_sdp_line, \
 311     .close            = asfrtp_close_context, \
 312     .parse_packet     = asfrtp_parse_packet,   \
 313 }
 314
 315 RTP_ASF_HANDLER(asf_pfv, "x-asf-pf",  AVMEDIA_TYPE_VIDEO);
 316 RTP_ASF_HANDLER(asf_pfa, "x-asf-pf",  AVMEDIA_TYPE_AUDIO);