| 1 | /* |
| 2 | * RTP H.263 Depacketizer, RFC 2190 |
| 3 | * Copyright (c) 2012 Martin Storsjo |
| 4 | * Based on the GStreamer H.263 Depayloder: |
| 5 | * Copyright 2005 Wim Taymans |
| 6 | * Copyright 2007 Edward Hervey |
| 7 | * Copyright 2007 Nokia Corporation |
| 8 | * Copyright 2007 Collabora Ltd, Philippe Kalaf |
| 9 | * Copyright 2010 Mark Nauwelaerts |
| 10 | * |
| 11 | * This file is part of FFmpeg. |
| 12 | * |
| 13 | * FFmpeg is free software; you can redistribute it and/or |
| 14 | * modify it under the terms of the GNU Lesser General Public |
| 15 | * License as published by the Free Software Foundation; either |
| 16 | * version 2.1 of the License, or (at your option) any later version. |
| 17 | * |
| 18 | * FFmpeg is distributed in the hope that it will be useful, |
| 19 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 20 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 21 | * Lesser General Public License for more details. |
| 22 | * |
| 23 | * You should have received a copy of the GNU Lesser General Public |
| 24 | * License along with FFmpeg; if not, write to the Free Software |
| 25 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 26 | */ |
| 27 | |
| 28 | #include "avformat.h" |
| 29 | #include "rtpdec_formats.h" |
| 30 | #include "libavutil/attributes.h" |
| 31 | #include "libavutil/intreadwrite.h" |
| 32 | #include "libavcodec/get_bits.h" |
| 33 | |
| 34 | struct PayloadContext { |
| 35 | AVIOContext *buf; |
| 36 | uint8_t endbyte; |
| 37 | int endbyte_bits; |
| 38 | uint32_t timestamp; |
| 39 | int newformat; |
| 40 | }; |
| 41 | |
| 42 | static PayloadContext *h263_new_context(void) |
| 43 | { |
| 44 | return av_mallocz(sizeof(PayloadContext)); |
| 45 | } |
| 46 | |
| 47 | static void h263_free_context(PayloadContext *data) |
| 48 | { |
| 49 | if (!data) |
| 50 | return; |
| 51 | if (data->buf) { |
| 52 | uint8_t *p; |
| 53 | avio_close_dyn_buf(data->buf, &p); |
| 54 | av_free(p); |
| 55 | } |
| 56 | av_free(data); |
| 57 | } |
| 58 | |
| 59 | static av_cold int h263_init(AVFormatContext *ctx, int st_index, PayloadContext *data) |
| 60 | { |
| 61 | if (st_index < 0) |
| 62 | return 0; |
| 63 | ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL; |
| 64 | return 0; |
| 65 | } |
| 66 | |
| 67 | static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, |
| 68 | AVStream *st, AVPacket *pkt, uint32_t *timestamp, |
| 69 | const uint8_t *buf, int len, uint16_t seq, |
| 70 | int flags) |
| 71 | { |
| 72 | /* Corresponding to header fields in the RFC */ |
| 73 | int f, p, i, sbit, ebit, src, r; |
| 74 | int header_size, ret; |
| 75 | |
| 76 | if (data->newformat) |
| 77 | return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, len, |
| 78 | seq, flags); |
| 79 | |
| 80 | if (data->buf && data->timestamp != *timestamp) { |
| 81 | /* Dropping old buffered, unfinished data */ |
| 82 | uint8_t *p; |
| 83 | avio_close_dyn_buf(data->buf, &p); |
| 84 | av_free(p); |
| 85 | data->buf = NULL; |
| 86 | } |
| 87 | |
| 88 | if (len < 4) { |
| 89 | av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len); |
| 90 | return AVERROR_INVALIDDATA; |
| 91 | } |
| 92 | |
| 93 | f = buf[0] & 0x80; |
| 94 | p = buf[0] & 0x40; |
| 95 | if (!f) { |
| 96 | /* Mode A */ |
| 97 | header_size = 4; |
| 98 | i = buf[1] & 0x10; |
| 99 | r = ((buf[1] & 0x01) << 3) | ((buf[2] & 0xe0) >> 5); |
| 100 | } else if (!p) { |
| 101 | /* Mode B */ |
| 102 | header_size = 8; |
| 103 | if (len < header_size) { |
| 104 | av_log(ctx, AV_LOG_ERROR, |
| 105 | "Too short H.263 RTP packet: %d bytes, %d header bytes\n", |
| 106 | len, header_size); |
| 107 | return AVERROR_INVALIDDATA; |
| 108 | } |
| 109 | r = buf[3] & 0x03; |
| 110 | i = buf[4] & 0x80; |
| 111 | } else { |
| 112 | /* Mode C */ |
| 113 | header_size = 12; |
| 114 | if (len < header_size) { |
| 115 | av_log(ctx, AV_LOG_ERROR, |
| 116 | "Too short H.263 RTP packet: %d bytes, %d header bytes\n", |
| 117 | len, header_size); |
| 118 | return AVERROR_INVALIDDATA; |
| 119 | } |
| 120 | r = buf[3] & 0x03; |
| 121 | i = buf[4] & 0x80; |
| 122 | } |
| 123 | sbit = (buf[0] >> 3) & 0x7; |
| 124 | ebit = buf[0] & 0x7; |
| 125 | src = (buf[1] & 0xe0) >> 5; |
| 126 | if (!(buf[0] & 0xf8)) { /* Reserved bits in RFC 2429/4629 are zero */ |
| 127 | if ((src == 0 || src >= 6) && r) { |
| 128 | /* Invalid src for this format, and bits that should be zero |
| 129 | * according to RFC 2190 aren't zero. */ |
| 130 | av_log(ctx, AV_LOG_WARNING, |
| 131 | "Interpreting H263 RTP data as RFC 2429/4629 even though " |
| 132 | "signalled with a static payload type.\n"); |
| 133 | data->newformat = 1; |
| 134 | return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, |
| 135 | len, seq, flags); |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | buf += header_size; |
| 140 | len -= header_size; |
| 141 | |
| 142 | if (!data->buf) { |
| 143 | /* Check the picture start code, only start buffering a new frame |
| 144 | * if this is correct */ |
| 145 | if (len > 4 && AV_RB32(buf) >> 10 == 0x20) { |
| 146 | ret = avio_open_dyn_buf(&data->buf); |
| 147 | if (ret < 0) |
| 148 | return ret; |
| 149 | data->timestamp = *timestamp; |
| 150 | } else { |
| 151 | /* Frame not started yet, skipping */ |
| 152 | return AVERROR(EAGAIN); |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | if (data->endbyte_bits || sbit) { |
| 157 | if (data->endbyte_bits == sbit) { |
| 158 | data->endbyte |= buf[0] & (0xff >> sbit); |
| 159 | data->endbyte_bits = 0; |
| 160 | buf++; |
| 161 | len--; |
| 162 | avio_w8(data->buf, data->endbyte); |
| 163 | } else { |
| 164 | /* Start/end skip bits not matching - missed packets? */ |
| 165 | GetBitContext gb; |
| 166 | init_get_bits(&gb, buf, len*8 - ebit); |
| 167 | skip_bits(&gb, sbit); |
| 168 | if (data->endbyte_bits) { |
| 169 | data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits); |
| 170 | avio_w8(data->buf, data->endbyte); |
| 171 | } |
| 172 | while (get_bits_left(&gb) >= 8) |
| 173 | avio_w8(data->buf, get_bits(&gb, 8)); |
| 174 | data->endbyte_bits = get_bits_left(&gb); |
| 175 | if (data->endbyte_bits) |
| 176 | data->endbyte = get_bits(&gb, data->endbyte_bits) << |
| 177 | (8 - data->endbyte_bits); |
| 178 | ebit = 0; |
| 179 | len = 0; |
| 180 | } |
| 181 | } |
| 182 | if (ebit) { |
| 183 | if (len > 0) |
| 184 | avio_write(data->buf, buf, len - 1); |
| 185 | data->endbyte_bits = 8 - ebit; |
| 186 | data->endbyte = buf[len - 1] & (0xff << ebit); |
| 187 | } else { |
| 188 | avio_write(data->buf, buf, len); |
| 189 | } |
| 190 | |
| 191 | if (!(flags & RTP_FLAG_MARKER)) |
| 192 | return AVERROR(EAGAIN); |
| 193 | |
| 194 | if (data->endbyte_bits) |
| 195 | avio_w8(data->buf, data->endbyte); |
| 196 | data->endbyte_bits = 0; |
| 197 | |
| 198 | ret = ff_rtp_finalize_packet(pkt, &data->buf, st->index); |
| 199 | if (ret < 0) |
| 200 | return ret; |
| 201 | if (!i) |
| 202 | pkt->flags |= AV_PKT_FLAG_KEY; |
| 203 | |
| 204 | return 0; |
| 205 | } |
| 206 | |
| 207 | RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = { |
| 208 | .codec_type = AVMEDIA_TYPE_VIDEO, |
| 209 | .codec_id = AV_CODEC_ID_H263, |
| 210 | .init = h263_init, |
| 211 | .parse_packet = h263_handle_packet, |
| 212 | .alloc = h263_new_context, |
| 213 | .free = h263_free_context, |
| 214 | .static_payload_id = 34, |
| 215 | }; |