FFmpeg/libavformat/rtpdec_h264.c

/*
 * RTP H264 Protocol (RFC3984)
 * Copyright (c) 2006 Ryan Martell
 *
 * 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
 */

/**
 * @file
 * @brief H.264 / RTP Code (RFC3984)
 * @author Ryan Martell <rdm4@martellventures.com>
 *
 * @note Notes:
 * Notes:
 * This currently supports packetization mode:
 * Single Nal Unit Mode (0), or
 * Non-Interleaved Mode (1).  It currently does not support
 * Interleaved Mode (2). (This requires implementing STAP-B, MTAP16, MTAP24,
 *                        FU-B packet types)
 */

#include "libavutil/attributes.h"
#include "libavutil/base64.h"
#include "libavutil/avstring.h"
#include "libavcodec/get_bits.h"
#include "avformat.h"

#include "network.h"

#include "rtpdec.h"
#include "rtpdec_formats.h"

struct PayloadContext {
    // sdp setup parameters
    uint8_t profile_idc;
    uint8_t profile_iop;
    uint8_t level_idc;
    int packetization_mode;
#ifdef DEBUG
    int packet_types_received[32];
#endif
};

#ifdef DEBUG
#define COUNT_NAL_TYPE(data, nal) data->packet_types_received[(nal) & 0x1f]++
#else
#define COUNT_NAL_TYPE(data, nal) do { } while (0)
#endif

static const uint8_t start_sequence[] = { 0, 0, 0, 1 };

static void parse_profile_level_id(AVFormatContext *s,
                                   PayloadContext *h264_data,
                                   char *value)
{
    char buffer[3];
    // 6 characters=3 bytes, in hex.
    uint8_t profile_idc;
    uint8_t profile_iop;
    uint8_t level_idc;

    buffer[0]   = value[0];
    buffer[1]   = value[1];
    buffer[2]   = '\0';
    profile_idc = strtol(buffer, NULL, 16);
    buffer[0]   = value[2];
    buffer[1]   = value[3];
    profile_iop = strtol(buffer, NULL, 16);
    buffer[0]   = value[4];
    buffer[1]   = value[5];
    level_idc   = strtol(buffer, NULL, 16);

    av_log(s, AV_LOG_DEBUG,
           "RTP Profile IDC: %x Profile IOP: %x Level: %x\n",
           profile_idc, profile_iop, level_idc);
    h264_data->profile_idc = profile_idc;
    h264_data->profile_iop = profile_iop;
    h264_data->level_idc   = level_idc;
}

static int parse_sprop_parameter_sets(AVFormatContext *s,
                                      AVCodecContext *codec,
                                      char *value)
{
    char base64packet[1024];
    uint8_t decoded_packet[1024];
    int packet_size;

    while (*value) {
        char *dst = base64packet;

        while (*value && *value != ','
               && (dst - base64packet) < sizeof(base64packet) - 1) {
            *dst++ = *value++;
        }
        *dst++ = '\0';

        if (*value == ',')
            value++;

        packet_size = av_base64_decode(decoded_packet, base64packet,
                                       sizeof(decoded_packet));
        if (packet_size > 0) {
            uint8_t *dest = av_malloc(packet_size + sizeof(start_sequence) +
                                      codec->extradata_size +
                                      FF_INPUT_BUFFER_PADDING_SIZE);
            if (!dest) {
                av_log(s, AV_LOG_ERROR,
                       "Unable to allocate memory for extradata!\n");
                return AVERROR(ENOMEM);
            }
            if (codec->extradata_size) {
                memcpy(dest, codec->extradata, codec->extradata_size);
                av_free(codec->extradata);
            }

            memcpy(dest + codec->extradata_size, start_sequence,
                   sizeof(start_sequence));
            memcpy(dest + codec->extradata_size + sizeof(start_sequence),
                   decoded_packet, packet_size);
            memset(dest + codec->extradata_size + sizeof(start_sequence) +
                   packet_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

            codec->extradata       = dest;
            codec->extradata_size += sizeof(start_sequence) + packet_size;
        }
    }

    av_log(s, AV_LOG_DEBUG, "Extradata set to %p (size: %d)\n",
           codec->extradata, codec->extradata_size);

    return 0;
}

static int sdp_parse_fmtp_config_h264(AVFormatContext *s,
                                      AVStream *stream,
                                      PayloadContext *h264_data,
                                      char *attr, char *value)
{
    AVCodecContext *codec = stream->codec;

    if (!strcmp(attr, "packetization-mode")) {
        av_log(s, AV_LOG_DEBUG, "RTP Packetization Mode: %d\n", atoi(value));
        h264_data->packetization_mode = atoi(value);
        /*
         * Packetization Mode:
         * 0 or not present: Single NAL mode (Only nals from 1-23 are allowed)
         * 1: Non-interleaved Mode: 1-23, 24 (STAP-A), 28 (FU-A) are allowed.
         * 2: Interleaved Mode: 25 (STAP-B), 26 (MTAP16), 27 (MTAP24), 28 (FU-A),
         *                      and 29 (FU-B) are allowed.
         */
        if (h264_data->packetization_mode > 1)
            av_log(s, AV_LOG_ERROR,
                   "Interleaved RTP mode is not supported yet.\n");
    } else if (!strcmp(attr, "profile-level-id")) {
        if (strlen(value) == 6)
            parse_profile_level_id(s, h264_data, value);
    } else if (!strcmp(attr, "sprop-parameter-sets")) {
        codec->extradata_size = 0;
        av_freep(&codec->extradata);
        return parse_sprop_parameter_sets(s, codec, value);
    }
    return 0;
}

static int h264_handle_packet_stap_a(AVFormatContext *ctx, PayloadContext *data, AVPacket *pkt,
                                     const uint8_t *buf, int len)
{
    int pass         = 0;
    int total_length = 0;
    uint8_t *dst     = NULL;
    int ret;

    for (pass = 0; pass < 2; pass++) {
        const uint8_t *src = buf;
        int src_len        = len;

        while (src_len > 2) {
            uint16_t nal_size = AV_RB16(src);

            // consume the length of the aggregate
            src     += 2;
            src_len -= 2;

            if (nal_size <= src_len) {
                if (pass == 0) {
                    // counting
                    total_length += sizeof(start_sequence) + nal_size;
                } else {
                    // copying
                    memcpy(dst, start_sequence, sizeof(start_sequence));
                    dst += sizeof(start_sequence);
                    memcpy(dst, src, nal_size);
                    COUNT_NAL_TYPE(data, *src);
                    dst += nal_size;
                }
            } else {
                av_log(ctx, AV_LOG_ERROR,
                       "nal size exceeds length: %d %d\n", nal_size, src_len);
            }

            // eat what we handled
            src     += nal_size;
            src_len -= nal_size;

            if (src_len < 0)
                av_log(ctx, AV_LOG_ERROR,
                       "Consumed more bytes than we got! (%d)\n", src_len);
        }

        if (pass == 0) {
            /* now we know the total size of the packet (with the
             * start sequences added) */
            if ((ret = av_new_packet(pkt, total_length)) < 0)
                return ret;
            dst = pkt->data;
        }
    }

    return 0;
}

static int h264_handle_packet_fu_a(AVFormatContext *ctx, PayloadContext *data, AVPacket *pkt,
                                   const uint8_t *buf, int len)
{
    uint8_t fu_indicator, fu_header, start_bit, nal_type, nal;
    int ret;

    if (len < 3) {
        av_log(ctx, AV_LOG_ERROR, "Too short data for FU-A H264 RTP packet\n");
        return AVERROR_INVALIDDATA;
    }

    fu_indicator = buf[0];
    fu_header    = buf[1];
    start_bit    = fu_header >> 7;
    nal_type     = fu_header & 0x1f;
    nal          = fu_indicator & 0xe0 | nal_type;

    // skip the fu_indicator and fu_header
    buf += 2;
    len -= 2;

    if (start_bit) {
        COUNT_NAL_TYPE(data, nal_type);
        /* copy in the start sequence, and the reconstructed nal */
        if ((ret = av_new_packet(pkt, sizeof(start_sequence) + sizeof(nal) + len)) < 0)
            return ret;
        memcpy(pkt->data, start_sequence, sizeof(start_sequence));
        pkt->data[sizeof(start_sequence)] = nal;
        memcpy(pkt->data + sizeof(start_sequence) + sizeof(nal), buf, len);
    } else {
        if ((ret = av_new_packet(pkt, len)) < 0)
            return ret;
        memcpy(pkt->data, buf, len);
    }

    return 0;
}

// return 0 on packet, no more left, 1 on packet, 1 on partial packet
static int h264_handle_packet(AVFormatContext *ctx, PayloadContext *data,
                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
                              const uint8_t *buf, int len, uint16_t seq,
                              int flags)
{
    uint8_t nal;
    uint8_t type;
    int result = 0;

    if (!len) {
        av_log(ctx, AV_LOG_ERROR, "Empty H264 RTP packet\n");
        return AVERROR_INVALIDDATA;
    }
    nal  = buf[0];
    type = nal & 0x1f;

    /* Simplify the case (these are all the nal types used internally by
     * the h264 codec). */
    if (type >= 1 && type <= 23)
        type = 1;
    switch (type) {
    case 0:                    // undefined, but pass them through
    case 1:
        if ((result = av_new_packet(pkt, len + sizeof(start_sequence))) < 0)
            return result;
        memcpy(pkt->data, start_sequence, sizeof(start_sequence));
        memcpy(pkt->data + sizeof(start_sequence), buf, len);
        COUNT_NAL_TYPE(data, nal);
        break;

    case 24:                   // STAP-A (one packet, multiple nals)
        // consume the STAP-A NAL
        buf++;
        len--;
        // first we are going to figure out the total size
        result = h264_handle_packet_stap_a(ctx, data, pkt, buf, len);
        break;

    case 25:                   // STAP-B
    case 26:                   // MTAP-16
    case 27:                   // MTAP-24
    case 29:                   // FU-B
        av_log(ctx, AV_LOG_ERROR,
               "Unhandled type (%d) (See RFC for implementation details\n",
               type);
        result = AVERROR(ENOSYS);
        break;

    case 28:                   // FU-A (fragmented nal)
        result = h264_handle_packet_fu_a(ctx, data, pkt, buf, len);
        break;

    case 30:                   // undefined
    case 31:                   // undefined
    default:
        av_log(ctx, AV_LOG_ERROR, "Undefined type (%d)\n", type);
        result = AVERROR_INVALIDDATA;
        break;
    }

    pkt->stream_index = st->index;

    return result;
}

static PayloadContext *h264_new_context(void)
{
    return av_mallocz(sizeof(PayloadContext) + FF_INPUT_BUFFER_PADDING_SIZE);
}

static void h264_free_context(PayloadContext *data)
{
#ifdef DEBUG
    int ii;

    for (ii = 0; ii < 32; ii++) {
        if (data->packet_types_received[ii])
            av_log(NULL, AV_LOG_DEBUG, "Received %d packets of type %d\n",
                   data->packet_types_received[ii], ii);
    }
#endif

    av_free(data);
}

static av_cold int h264_init(AVFormatContext *s, int st_index,
                             PayloadContext *data)
{
    if (st_index < 0)
        return 0;
    s->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
    return 0;
}

static int parse_h264_sdp_line(AVFormatContext *s, int st_index,
                               PayloadContext *h264_data, const char *line)
{
    AVStream *stream;
    AVCodecContext *codec;
    const char *p = line;

    if (st_index < 0)
        return 0;

    stream = s->streams[st_index];
    codec  = stream->codec;

    if (av_strstart(p, "framesize:", &p)) {
        char buf1[50];
        char *dst = buf1;

        // remove the protocol identifier
        while (*p && *p == ' ')
            p++;                     // strip spaces.
        while (*p && *p != ' ')
            p++;                     // eat protocol identifier
        while (*p && *p == ' ')
            p++;                     // strip trailing spaces.
        while (*p && *p != '-' && (dst - buf1) < sizeof(buf1) - 1)
            *dst++ = *p++;
        *dst = '\0';

        // a='framesize:96 320-240'
        // set our parameters
        codec->width   = atoi(buf1);
        codec->height  = atoi(p + 1); // skip the -
    } else if (av_strstart(p, "fmtp:", &p)) {
        return ff_parse_fmtp(s, stream, h264_data, p, sdp_parse_fmtp_config_h264);
    } else if (av_strstart(p, "cliprect:", &p)) {
        // could use this if we wanted.
    }

    return 0;
}

RTPDynamicProtocolHandler ff_h264_dynamic_handler = {
    .enc_name         = "H264",
    .codec_type       = AVMEDIA_TYPE_VIDEO,
    .codec_id         = AV_CODEC_ID_H264,
    .init             = h264_init,
    .parse_sdp_a_line = parse_h264_sdp_line,
    .alloc            = h264_new_context,
    .free             = h264_free_context,
    .parse_packet     = h264_handle_packet
};