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Rev | Author | Line No. | Line |
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6148 | serge | 1 | /* |
2 | * RTP H.263 Depacketizer, RFC 4629 |
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3 | * Copyright (c) 2010 Martin Storsjo |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | #include "avformat.h" |
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23 | #include "rtpdec_formats.h" |
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24 | #include "libavutil/attributes.h" |
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25 | #include "libavutil/intreadwrite.h" |
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26 | |||
27 | static av_cold int h263_init(AVFormatContext *ctx, int st_index, |
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28 | PayloadContext *data) |
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29 | { |
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30 | if (st_index < 0) |
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31 | return 0; |
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32 | ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL; |
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33 | return 0; |
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34 | } |
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35 | |||
36 | int ff_h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, |
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37 | AVStream *st, AVPacket *pkt, uint32_t *timestamp, |
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38 | const uint8_t *buf, int len, uint16_t seq, int flags) |
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39 | { |
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40 | uint8_t *ptr; |
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41 | uint16_t header; |
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42 | int startcode, vrc, picture_header; |
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43 | |||
44 | if (len < 2) { |
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45 | av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet\n"); |
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46 | return AVERROR_INVALIDDATA; |
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47 | } |
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48 | |||
49 | /* Decode the 16 bit H.263+ payload header, as described in section |
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50 | * 5.1 of RFC 4629. The fields of this header are: |
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51 | * - 5 reserved bits, should be ignored. |
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52 | * - One bit (P, startcode), indicating a picture start, picture segment |
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53 | * start or video sequence end. If set, two zero bytes should be |
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54 | * prepended to the payload. |
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55 | * - One bit (V, vrc), indicating the presence of an 8 bit Video |
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56 | * Redundancy Coding field after this 16 bit header. |
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57 | * - 6 bits (PLEN, picture_header), the length (in bytes) of an extra |
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58 | * picture header, following the VRC field. |
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59 | * - 3 bits (PEBIT), the number of bits to ignore of the last byte |
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60 | * of the extra picture header. (Not used at the moment.) |
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61 | */ |
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62 | header = AV_RB16(buf); |
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63 | startcode = (header & 0x0400) >> 9; |
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64 | vrc = header & 0x0200; |
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65 | picture_header = (header & 0x01f8) >> 3; |
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66 | buf += 2; |
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67 | len -= 2; |
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68 | |||
69 | if (vrc) { |
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70 | /* Skip VRC header if present, not used at the moment. */ |
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71 | buf += 1; |
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72 | len -= 1; |
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73 | } |
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74 | if (picture_header) { |
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75 | /* Skip extra picture header if present, not used at the moment. */ |
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76 | buf += picture_header; |
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77 | len -= picture_header; |
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78 | } |
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79 | |||
80 | if (len < 0) { |
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81 | av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet\n"); |
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82 | return AVERROR_INVALIDDATA; |
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83 | } |
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84 | |||
85 | if (av_new_packet(pkt, len + startcode)) { |
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86 | av_log(ctx, AV_LOG_ERROR, "Out of memory\n"); |
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87 | return AVERROR(ENOMEM); |
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88 | } |
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89 | pkt->stream_index = st->index; |
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90 | ptr = pkt->data; |
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91 | |||
92 | if (startcode) { |
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93 | *ptr++ = 0; |
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94 | *ptr++ = 0; |
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95 | } |
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96 | memcpy(ptr, buf, len); |
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97 | |||
98 | return 0; |
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99 | } |
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100 | |||
101 | RTPDynamicProtocolHandler ff_h263_1998_dynamic_handler = { |
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102 | .enc_name = "H263-1998", |
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103 | .codec_type = AVMEDIA_TYPE_VIDEO, |
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104 | .codec_id = AV_CODEC_ID_H263, |
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105 | .init = h263_init, |
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106 | .parse_packet = ff_h263_handle_packet, |
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107 | }; |
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108 | |||
109 | RTPDynamicProtocolHandler ff_h263_2000_dynamic_handler = { |
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110 | .enc_name = "H263-2000", |
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111 | .codec_type = AVMEDIA_TYPE_VIDEO, |
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112 | .codec_id = AV_CODEC_ID_H263, |
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113 | .init = h263_init, |
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114 | .parse_packet = ff_h263_handle_packet, |
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115 | };>>> |