PeerStreamer

/*

 * QDesign Music 2 (QDM2) payload for RTP

 * Copyright (c) 2010 Ronald S. Bultje

 *

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * @brief RTP support for the QDM2 payload (todo: wiki)

 * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>

 */

#include <string.h>

#include "libavutil/intreadwrite.h"

#include "libavcodec/avcodec.h"

#include "rtp.h"

#include "rtpdec.h"

#include "rtpdec_formats.h"

struct PayloadContext {

    /** values read from the config header, used as packet headers */

    //@{

    int block_type;            ///< superblock type, value 2 .. 8

    int block_size;            ///< from extradata, used as pkt length

    int subpkts_per_block;     ///< max. nr. of subpackets to add per output buffer

    //@}

    /** Temporary storage for superblock restoring, per packet ID (0x80 total) */

    //@{

    uint16_t len[0x80];        ///< how much the temporary buffer is filled

    uint8_t  buf[0x80][0x800]; ///< the temporary storage buffer

    unsigned int cache;        ///< number of data packets that we have cached right now

    unsigned int n_pkts;       ///< number of RTP packets received since last packet output / config

    uint32_t timestamp;        ///< timestamp of next-to-be-returned packet

    //@}

};

/**

 * Parses configuration (basically the codec-specific extradata) from

 * a RTP config subpacket (starts with 0xff).

 *

 * Layout of the config subpacket (in bytes):

 * 1: 0xFF          <- config ID

 * then an array {

 *     1: size      <- of the current item

 *     1: item type <- 0 .. 4

 *     size-2: data <- data depends on the item type

 * }

 *

 * Item 0 implies the end of the config subpacket, and has no data.

 * Item 1 implies a stream configuration without extradata.

 * Item 2 max. nr. of subpackets per superblock

 * Item 3 superblock type for the stream

 * Item 4 implies a stream configuration with extradata (size >= 0x1c).

 *

 * @return <0 on error, otherwise the number of bytes parsed from the

 *         input buffer.

 */

static int qdm2_parse_config(PayloadContext *qdm, AVStream *st,

                             const uint8_t *buf, const uint8_t *end)

{

    const uint8_t *p = buf;

    while (end - p >= 2) {

        unsigned int item_len = p[0], config_item = p[1];

        if (item_len < 2 || end - p < item_len || config_item > 4)

            return AVERROR_INVALIDDATA;

        switch (config_item) {

            case 0: /* end of config block */

                return p - buf + item_len;

            case 1: /* stream without extradata */

                /* FIXME: set default qdm->block_size */

                break;

            case 2: /**< subpackets per block */

                if (item_len < 3)

                    return AVERROR_INVALIDDATA;

                qdm->subpkts_per_block = p[2];

                break;

            case 3: /* superblock type */

                if (item_len < 4)

                    return AVERROR_INVALIDDATA;

                qdm->block_type = AV_RB16(p + 2);

                break;

            case 4: /* stream with extradata */

                if (item_len < 30)

                    return AVERROR_INVALIDDATA;

                av_freep(&st->codec->extradata);

                st->codec->extradata_size = 26 + item_len;

                if (!(st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE))) {

                    st->codec->extradata_size = 0;

                    return AVERROR(ENOMEM);

                }

                AV_WB32(st->codec->extradata, 12);

                memcpy(st->codec->extradata + 4, "frma", 4);

                memcpy(st->codec->extradata + 8, "QDM2", 4);

                AV_WB32(st->codec->extradata + 12, 6 + item_len);

                memcpy(st->codec->extradata + 16, "QDCA", 4);

                memcpy(st->codec->extradata + 20, p + 2, item_len - 2);

                AV_WB32(st->codec->extradata + 18 + item_len, 8);

                AV_WB32(st->codec->extradata + 22 + item_len, 0);

                qdm->block_size = AV_RB32(p + 26);

                break;

        }

        p += item_len;

    }

    return AVERROR(EAGAIN); /* not enough data */

}

/**

 * Parses a single subpacket. We store this subpacket in an intermediate

 * buffer (position depends on the ID (byte[0]). When called, at least

 * 4 bytes are available for reading (see qdm2_parse_packet()).

 *

 * Layout of a single subpacket (RTP packets commonly contain multiple

 * such subpackets) - length in bytes:

 * 1:    ordering ID        <- 0 .. 0x7F

 * 1:    subpacket type     <- 0 .. 0x7F; value & 0x80 means subpacket length = 2 bytes, else 1 byte

 * 1/2:  subpacket length   <- length of the data following the flags/length fields

 * if (subpacket type & 0x7F) == 0x7F

 *   1:  subpacket type, higher bits

 * size: subpacket data

 *

 * The subpackets come in randomly, and should be encapsulated into 1

 * or more superblocks (containing qdm->subpkts_per_block subpackets

 * each) per RTP packet, in order of ascending "ordering ID", see

 * qdm2_restore_block().

 *

 * @return <0 on error, otherwise the number of bytes parsed from the

 *         input buffer.

 */

static int qdm2_parse_subpacket(PayloadContext *qdm, AVStream *st,

                                const uint8_t *buf, const uint8_t *end)

{

    const uint8_t *p = buf;

    unsigned int id, len, type, to_copy;

    /* parse header so we know the size of the header/data */

    id       = *p++;

    type     = *p++;

    if (type & 0x80) {

        len   = AV_RB16(p);

        p    += 2;

        type &= 0x7F;

    } else

        len = *p++;

    if (end - p < len + (type == 0x7F) || id >= 0x80)

        return AVERROR_INVALIDDATA;

    if (type == 0x7F)

        type |= *p++ << 8;

    /* copy data into a temporary buffer */

    to_copy = FFMIN(len + (p - &buf[1]), 0x800 - qdm->len[id]);

    memcpy(&qdm->buf[id][qdm->len[id]], buf + 1, to_copy);

    qdm->len[id] += to_copy;

    return p + len - buf;

}

/**

 * Adds a superblock header around a set of subpackets.

 *

 * @return <0 on error, else 0.

 */

static int qdm2_restore_block(PayloadContext *qdm, AVStream *st, AVPacket *pkt)

{

    int to_copy, n, res, include_csum;

    uint8_t *p, *csum_pos = NULL;

    /* create packet to hold subpkts into a superblock */

    assert(qdm->cache > 0);

    for (n = 0; n < 0x80; n++)

        if (qdm->len[n] > 0)

            break;

    assert(n < 0x80);

    if ((res = av_new_packet(pkt, qdm->block_size)) < 0)

        return res;

    memset(pkt->data, 0, pkt->size);

    pkt->stream_index  = st->index;

    p                  = pkt->data;

    /* superblock header */

    if (qdm->len[n] > 0xff) {

        *p++ = qdm->block_type | 0x80;

        AV_WB16(p, qdm->len[n]);

        p   += 2;

    } else {

        *p++ = qdm->block_type;

        *p++ = qdm->len[n];

    }

    if ((include_csum = (qdm->block_type == 2 || qdm->block_type == 4))) {

        csum_pos = p;

        p       += 2;

    }

    /* subpacket data */

    to_copy = FFMIN(qdm->len[n], pkt->size - (p - pkt->data));

    memcpy(p, qdm->buf[n], to_copy);

    qdm->len[n] = 0;

    /* checksum header */

    if (include_csum) {

        unsigned int total = 0;

        uint8_t *q;

        for (q = pkt->data; q < &pkt->data[qdm->block_size]; q++)

            total += *q;

        AV_WB16(csum_pos, (uint16_t) total);

    }

    return 0;

}

/** return 0 on packet, no more left, 1 on packet, -1 on partial packet... */

static int qdm2_parse_packet(AVFormatContext *s, PayloadContext *qdm,

                             AVStream *st, AVPacket *pkt,

                             uint32_t *timestamp,

                             const uint8_t *buf, int len, int flags)

{

    int res = AVERROR_INVALIDDATA, n;

    const uint8_t *end = buf + len, *p = buf;

    if (len > 0) {

        if (len < 2)

            return AVERROR_INVALIDDATA;

        /* configuration block */

        if (*p == 0xff) {

            if (qdm->n_pkts > 0) {

                av_log(s, AV_LOG_WARNING,

                       "Out of sequence config - dropping queue\n");

                qdm->n_pkts = 0;

                memset(qdm->len, 0, sizeof(qdm->len));

            }

            if ((res = qdm2_parse_config(qdm, st, ++p, end)) < 0)

                return res;

            p += res;

            /* We set codec_id to CODEC_ID_NONE initially to

             * delay decoder initialization since extradata is

             * carried within the RTP stream, not SDP. Here,

             * by setting codec_id to CODEC_ID_QDM2, we are signalling

             * to the decoder that it is OK to initialize. */

            st->codec->codec_id = CODEC_ID_QDM2;

        }

        /* subpackets */

        while (end - p >= 4) {

            if ((res = qdm2_parse_subpacket(qdm, st, p, end)) < 0)

                return res;

            p += res;

        }

        qdm->timestamp = *timestamp;

        if (++qdm->n_pkts < qdm->subpkts_per_block)

            return AVERROR(EAGAIN);

        qdm->cache = 0;

        for (n = 0; n < 0x80; n++)

            if (qdm->len[n] > 0)

                qdm->cache++;

    }

    /* output the subpackets into freshly created superblock structures */

    if (!qdm->cache || (res = qdm2_restore_block(qdm, st, pkt)) < 0)

        return res;

    if (--qdm->cache == 0)

        qdm->n_pkts = 0;

    *timestamp = qdm->timestamp;

    qdm->timestamp = RTP_NOTS_VALUE;

    return (qdm->cache > 0) ? 1 : 0;

}

static PayloadContext *qdm2_extradata_new(void)

{

    return av_mallocz(sizeof(PayloadContext));

}

static void qdm2_extradata_free(PayloadContext *qdm)

{

    av_free(qdm);

}

RTPDynamicProtocolHandler ff_qdm2_dynamic_handler = {

    .enc_name         = "X-QDM",

    .codec_type       = AVMEDIA_TYPE_AUDIO,

    .codec_id         = CODEC_ID_NONE,

    .open             = qdm2_extradata_new,

    .close            = qdm2_extradata_free,

    .parse_packet     = qdm2_parse_packet,

};