libavformat/rtpdec_qdm2.c

   1 /*
   2  * QDesign Music 2 (QDM2) payload for RTP
   3  * Copyright (c) 2010 Ronald S. Bultje
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 RTP support for the QDM2 payload (todo: wiki)
  25  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
  26  */
  27
  28 #include <string.h>
  29 #include "libavutil/intreadwrite.h"
  30 #include "libavcodec/avcodec.h"
  31 #include "rtp.h"
  32 #include "rtpdec.h"
  33 #include "rtpdec_formats.h"
  34
  35 struct PayloadContext {
  36     /** values read from the config header, used as packet headers */
  37     //@{
  38     int block_type;            ///< superblock type, value 2 .. 8
  39     int block_size;            ///< from extradata, used as pkt length
  40     int subpkts_per_block;     ///< max. nr. of subpackets to add per output buffer
  41     //@}
  42
  43     /** Temporary storage for superblock restoring, per packet ID (0x80 total) */
  44     //@{
  45     uint16_t len[0x80];        ///< how much the temporary buffer is filled
  46     uint8_t  buf[0x80][0x800]; ///< the temporary storage buffer
  47
  48     unsigned int cache;        ///< number of data packets that we have cached right now
  49     unsigned int n_pkts;       ///< number of RTP packets received since last packet output / config
  50     uint32_t timestamp;        ///< timestamp of next-to-be-returned packet
  51     //@}
  52 };
  53
  54 /**
  55  * Parse configuration (basically the codec-specific extradata) from
  56  * an RTP config subpacket (starts with 0xff).
  57  *
  58  * Layout of the config subpacket (in bytes):
  59  * 1: 0xFF          <- config ID
  60  * then an array {
  61  *     1: size      <- of the current item
  62  *     1: item type <- 0 .. 4
  63  *     size-2: data <- data depends on the item type
  64  * }
  65  *
  66  * Item 0 implies the end of the config subpacket, and has no data.
  67  * Item 1 implies a stream configuration without extradata.
  68  * Item 2 max. nr. of subpackets per superblock
  69  * Item 3 superblock type for the stream
  70  * Item 4 implies a stream configuration with extradata (size >= 0x1c).
  71  *
  72  * @return <0 on error, otherwise the number of bytes parsed from the
  73  *         input buffer.
  74  */
  75 static int qdm2_parse_config(PayloadContext *qdm, AVStream *st,
  76                              const uint8_t *buf, const uint8_t *end)
  77 {
  78     const uint8_t *p = buf;
  79
  80     while (end - p >= 2) {
  81         unsigned int item_len = p[0], config_item = p[1];
  82
  83         if (item_len < 2 || end - p < item_len || config_item > 4)
  84             return AVERROR_INVALIDDATA;
  85
  86         switch (config_item) {
  87             case 0: /* end of config block */
  88                 return p - buf + item_len;
  89             case 1: /* stream without extradata */
  90                 /* FIXME: set default qdm->block_size */
  91                 break;
  92             case 2: /**< subpackets per block */
  93                 if (item_len < 3)
  94                     return AVERROR_INVALIDDATA;
  95                 qdm->subpkts_per_block = p[2];
  96                 break;
  97             case 3: /* superblock type */
  98                 if (item_len < 4)
  99                     return AVERROR_INVALIDDATA;
 100                 qdm->block_type = AV_RB16(p + 2);
 101                 break;
 102             case 4: /* stream with extradata */
 103                 if (item_len < 30)
 104                     return AVERROR_INVALIDDATA;
 105                 av_freep(&st->codec->extradata);
 106                 st->codec->extradata_size = 26 + item_len;
 107                 if (!(st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE))) {
 108                     st->codec->extradata_size = 0;
 109                     return AVERROR(ENOMEM);
 110                 }
 111                 AV_WB32(st->codec->extradata, 12);
 112                 memcpy(st->codec->extradata + 4, "frma", 4);
 113                 memcpy(st->codec->extradata + 8, "QDM2", 4);
 114                 AV_WB32(st->codec->extradata + 12, 6 + item_len);
 115                 memcpy(st->codec->extradata + 16, "QDCA", 4);
 116                 memcpy(st->codec->extradata + 20, p + 2, item_len - 2);
 117                 AV_WB32(st->codec->extradata + 18 + item_len, 8);
 118                 AV_WB32(st->codec->extradata + 22 + item_len, 0);
 119
 120                 qdm->block_size = AV_RB32(p + 26);
 121                 break;
 122         }
 123
 124         p += item_len;
 125     }
 126
 127     return AVERROR(EAGAIN); /* not enough data */
 128 }
 129
 130 /**
 131  * Parse a single subpacket. We store this subpacket in an intermediate
 132  * buffer (position depends on the ID (byte[0]). When called, at least
 133  * 4 bytes are available for reading (see qdm2_parse_packet()).
 134  *
 135  * Layout of a single subpacket (RTP packets commonly contain multiple
 136  * such subpackets) - length in bytes:
 137  * 1:    ordering ID        <- 0 .. 0x7F
 138  * 1:    subpacket type     <- 0 .. 0x7F; value & 0x80 means subpacket length = 2 bytes, else 1 byte
 139  * 1/2:  subpacket length   <- length of the data following the flags/length fields
 140  * if (subpacket type & 0x7F) == 0x7F
 141  *   1:  subpacket type, higher bits
 142  * size: subpacket data
 143  *
 144  * The subpackets come in randomly, and should be encapsulated into 1
 145  * or more superblocks (containing qdm->subpkts_per_block subpackets
 146  * each) per RTP packet, in order of ascending "ordering ID", see
 147  * qdm2_restore_block().
 148  *
 149  * @return <0 on error, otherwise the number of bytes parsed from the
 150  *         input buffer.
 151  */
 152 static int qdm2_parse_subpacket(PayloadContext *qdm, AVStream *st,
 153                                 const uint8_t *buf, const uint8_t *end)
 154 {
 155     const uint8_t *p = buf;
 156     unsigned int id, len, type, to_copy;
 157
 158     /* parse header so we know the size of the header/data */
 159     id       = *p++;
 160     type     = *p++;
 161     if (type & 0x80) {
 162         len   = AV_RB16(p);
 163         p    += 2;
 164         type &= 0x7F;
 165     } else
 166         len = *p++;
 167
 168     if (end - p < len + (type == 0x7F) || id >= 0x80)
 169         return AVERROR_INVALIDDATA;
 170     if (type == 0x7F)
 171         type |= *p++ << 8;
 172
 173     /* copy data into a temporary buffer */
 174     to_copy = FFMIN(len + (p - &buf[1]), 0x800 - qdm->len[id]);
 175     memcpy(&qdm->buf[id][qdm->len[id]], buf + 1, to_copy);
 176     qdm->len[id] += to_copy;
 177
 178     return p + len - buf;
 179 }
 180
 181 /**
 182  * Add a superblock header around a set of subpackets.
 183  *
 184  * @return <0 on error, else 0.
 185  */
 186 static int qdm2_restore_block(PayloadContext *qdm, AVStream *st, AVPacket *pkt)
 187 {
 188     int to_copy, n, res, include_csum;
 189     uint8_t *p, *csum_pos = NULL;
 190
 191     /* create packet to hold subpkts into a superblock */
 192     assert(qdm->cache > 0);
 193     for (n = 0; n < 0x80; n++)
 194         if (qdm->len[n] > 0)
 195             break;
 196     assert(n < 0x80);
 197
 198     if ((res = av_new_packet(pkt, qdm->block_size)) < 0)
 199         return res;
 200     memset(pkt->data, 0, pkt->size);
 201     pkt->stream_index  = st->index;
 202     p                  = pkt->data;
 203
 204     /* superblock header */
 205     if (qdm->len[n] > 0xff) {
 206         *p++ = qdm->block_type | 0x80;
 207         AV_WB16(p, qdm->len[n]);
 208         p   += 2;
 209     } else {
 210         *p++ = qdm->block_type;
 211         *p++ = qdm->len[n];
 212     }
 213     if ((include_csum = (qdm->block_type == 2 || qdm->block_type == 4))) {
 214         csum_pos = p;
 215         p       += 2;
 216     }
 217
 218     /* subpacket data */
 219     to_copy = FFMIN(qdm->len[n], pkt->size - (p - pkt->data));
 220     memcpy(p, qdm->buf[n], to_copy);
 221     qdm->len[n] = 0;
 222
 223     /* checksum header */
 224     if (include_csum) {
 225         unsigned int total = 0;
 226         uint8_t *q;
 227
 228         for (q = pkt->data; q < &pkt->data[qdm->block_size]; q++)
 229             total += *q;
 230         AV_WB16(csum_pos, (uint16_t) total);
 231     }
 232
 233     return 0;
 234 }
 235
 236 /** return 0 on packet, no more left, 1 on packet, -1 on partial packet... */
 237 static int qdm2_parse_packet(AVFormatContext *s, PayloadContext *qdm,
 238                              AVStream *st, AVPacket *pkt,
 239                              uint32_t *timestamp,
 240                              const uint8_t *buf, int len, uint16_t seq,
 241                              int flags)
 242 {
 243     int res = AVERROR_INVALIDDATA, n;
 244     const uint8_t *end = buf + len, *p = buf;
 245
 246     if (len > 0) {
 247         if (len < 2)
 248             return AVERROR_INVALIDDATA;
 249
 250         /* configuration block */
 251         if (*p == 0xff) {
 252             if (qdm->n_pkts > 0) {
 253                 av_log(s, AV_LOG_WARNING,
 254                        "Out of sequence config - dropping queue\n");
 255                 qdm->n_pkts = 0;
 256                 memset(qdm->len, 0, sizeof(qdm->len));
 257             }
 258
 259             if ((res = qdm2_parse_config(qdm, st, ++p, end)) < 0)
 260                 return res;
 261             p += res;
 262
 263             /* We set codec_id to AV_CODEC_ID_NONE initially to
 264              * delay decoder initialization since extradata is
 265              * carried within the RTP stream, not SDP. Here,
 266              * by setting codec_id to AV_CODEC_ID_QDM2, we are signalling
 267              * to the decoder that it is OK to initialize. */
 268             st->codec->codec_id = AV_CODEC_ID_QDM2;
 269         }
 270         if (st->codec->codec_id == AV_CODEC_ID_NONE)
 271             return AVERROR(EAGAIN);
 272
 273         /* subpackets */
 274         while (end - p >= 4) {
 275             if ((res = qdm2_parse_subpacket(qdm, st, p, end)) < 0)
 276                 return res;
 277             p += res;
 278         }
 279
 280         qdm->timestamp = *timestamp;
 281         if (++qdm->n_pkts < qdm->subpkts_per_block)
 282             return AVERROR(EAGAIN);
 283         qdm->cache = 0;
 284         for (n = 0; n < 0x80; n++)
 285             if (qdm->len[n] > 0)
 286                 qdm->cache++;
 287     }
 288
 289     /* output the subpackets into freshly created superblock structures */
 290     if (!qdm->cache || (res = qdm2_restore_block(qdm, st, pkt)) < 0)
 291         return res;
 292     if (--qdm->cache == 0)
 293         qdm->n_pkts = 0;
 294
 295     *timestamp = qdm->timestamp;
 296     qdm->timestamp = RTP_NOTS_VALUE;
 297
 298     return (qdm->cache > 0) ? 1 : 0;
 299 }
 300
 301 static PayloadContext *qdm2_extradata_new(void)
 302 {
 303     return av_mallocz(sizeof(PayloadContext));
 304 }
 305
 306 static void qdm2_extradata_free(PayloadContext *qdm)
 307 {
 308     av_free(qdm);
 309 }
 310
 311 RTPDynamicProtocolHandler ff_qdm2_dynamic_handler = {
 312     .enc_name         = "X-QDM",
 313     .codec_type       = AVMEDIA_TYPE_AUDIO,
 314     .codec_id         = AV_CODEC_ID_NONE,
 315     .alloc            = qdm2_extradata_new,
 316     .free             = qdm2_extradata_free,
 317     .parse_packet     = qdm2_parse_packet,
 318 };