libavcodec/opus_parser.c

   1 /*
   2  * Copyright (c) 2013-2014 Mozilla Corporation
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * Libav is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with Libav; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * Opus parser
  24  *
  25  * Determines the duration for each packet.
  26  */
  27
  28 #include "avcodec.h"
  29 #include "bytestream.h"
  30 #include "opus.h"
  31 #include "parser.h"
  32
  33 typedef struct OpusParseContext {
  34     OpusContext ctx;
  35     OpusPacket pkt;
  36     int extradata_parsed;
  37     ParseContext pc;
  38     int ts_framing;
  39 } OpusParseContext;
  40
  41 static const uint8_t *parse_opus_ts_header(const uint8_t *start, int *payload_len, int buf_len)
  42 {
  43     const uint8_t *buf = start + 1;
  44     int start_trim_flag, end_trim_flag, control_extension_flag, control_extension_length;
  45     uint8_t flags;
  46
  47     GetByteContext gb;
  48     bytestream2_init(&gb, buf, buf_len);
  49
  50     flags = bytestream2_get_byte(&gb);
  51     start_trim_flag        = (flags >> 4) & 1;
  52     end_trim_flag          = (flags >> 3) & 1;
  53     control_extension_flag = (flags >> 2) & 1;
  54
  55     *payload_len = 0;
  56     while (bytestream2_peek_byte(&gb) == 0xff)
  57         *payload_len += bytestream2_get_byte(&gb);
  58
  59     *payload_len += bytestream2_get_byte(&gb);
  60
  61     if (start_trim_flag)
  62         bytestream2_skip(&gb, 2);
  63     if (end_trim_flag)
  64         bytestream2_skip(&gb, 2);
  65     if (control_extension_flag) {
  66         control_extension_length = bytestream2_get_byte(&gb);
  67         bytestream2_skip(&gb, control_extension_length);
  68     }
  69
  70     return buf + bytestream2_tell(&gb);
  71 }
  72
  73 /**
  74  * Find the end of the current frame in the bitstream.
  75  * @return the position of the first byte of the next frame, or -1
  76  */
  77 static int opus_find_frame_end(AVCodecParserContext *ctx, AVCodecContext *avctx,
  78                                const uint8_t *buf, int buf_size, int *header_len)
  79 {
  80     OpusParseContext *s = ctx->priv_data;
  81     ParseContext *pc    = &s->pc;
  82     int ret, start_found, i = 0, payload_len = 0;
  83     const uint8_t *payload;
  84     uint32_t state;
  85     uint16_t hdr;
  86     *header_len = 0;
  87
  88     if (!buf_size)
  89         return 0;
  90
  91     start_found = pc->frame_start_found;
  92     state = pc->state;
  93     payload = buf;
  94
  95     /* Check if we're using Opus in MPEG-TS framing */
  96     if (!s->ts_framing && buf_size > 2) {
  97         hdr = AV_RB16(buf);
  98         if ((hdr & OPUS_TS_MASK) == OPUS_TS_HEADER)
  99             s->ts_framing = 1;
 100     }
 101
 102     if (s->ts_framing && !start_found) {
 103         for (i = 0; i < buf_size-2; i++) {
 104             state = (state << 8) | payload[i];
 105             if ((state & OPUS_TS_MASK) == OPUS_TS_HEADER) {
 106                 payload = parse_opus_ts_header(payload, &payload_len, buf_size - i);
 107                 *header_len = payload - buf;
 108                 start_found = 1;
 109                 break;
 110             }
 111         }
 112     }
 113
 114     if (!s->ts_framing)
 115         payload_len = buf_size;
 116
 117     if (avctx->extradata && !s->extradata_parsed) {
 118         ret = ff_opus_parse_extradata(avctx, &s->ctx);
 119         if (ret < 0) {
 120             av_log(avctx, AV_LOG_ERROR, "Error parsing Ogg extradata.\n");
 121             return AVERROR_INVALIDDATA;
 122         }
 123         av_freep(&s->ctx.channel_maps);
 124         s->extradata_parsed = 1;
 125     }
 126
 127     if (payload_len <= buf_size && (!s->ts_framing || start_found)) {
 128         ret = ff_opus_parse_packet(&s->pkt, payload, payload_len, s->ctx.nb_streams > 1);
 129         if (ret < 0) {
 130             av_log(avctx, AV_LOG_ERROR, "Error parsing Opus packet header.\n");
 131             pc->frame_start_found = 0;
 132             return AVERROR_INVALIDDATA;
 133         }
 134
 135         ctx->duration = s->pkt.frame_count * s->pkt.frame_duration;
 136     }
 137
 138     if (s->ts_framing) {
 139         if (start_found) {
 140             if (payload_len + *header_len <= buf_size) {
 141                 pc->frame_start_found = 0;
 142                 pc->state             = -1;
 143                 return payload_len + *header_len;
 144             }
 145         }
 146
 147         pc->frame_start_found = start_found;
 148         pc->state = state;
 149         return END_NOT_FOUND;
 150     }
 151
 152     return buf_size;
 153 }
 154
 155 static int opus_parse(AVCodecParserContext *ctx, AVCodecContext *avctx,
 156                        const uint8_t **poutbuf, int *poutbuf_size,
 157                        const uint8_t *buf, int buf_size)
 158 {
 159     OpusParseContext *s = ctx->priv_data;
 160     ParseContext *pc    = &s->pc;
 161     int next, header_len;
 162
 163     next = opus_find_frame_end(ctx, avctx, buf, buf_size, &header_len);
 164
 165     if (s->ts_framing && next != AVERROR_INVALIDDATA &&
 166         ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 167         *poutbuf      = NULL;
 168         *poutbuf_size = 0;
 169         return buf_size;
 170     }
 171
 172     if (next == AVERROR_INVALIDDATA){
 173         *poutbuf      = NULL;
 174         *poutbuf_size = 0;
 175         return buf_size;
 176     }
 177
 178     *poutbuf      = buf + header_len;
 179     *poutbuf_size = buf_size - header_len;
 180     return next;
 181 }
 182
 183 AVCodecParser ff_opus_parser = {
 184     .codec_ids      = { AV_CODEC_ID_OPUS },
 185     .priv_data_size = sizeof(OpusParseContext),
 186     .parser_parse   = opus_parse,
 187     .parser_close   = ff_parse_close
 188 };