git.sesse.net Git - ffmpeg/blob - libavcodec/tak_parser.c

   1 /*
   2  * TAK parser
   3  * Copyright (c) 2012 Michael Niedermayer
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * TAK parser
  25  **/
  26
  27 #include "tak.h"
  28 #include "parser.h"
  29
  30 typedef struct TAKParseContext {
  31     ParseContext  pc;
  32     TAKStreamInfo ti;
  33     int           index;
  34 } TAKParseContext;
  35
  36 static av_cold int tak_init(AVCodecParserContext *s)
  37 {
  38     ff_tak_init_crc();
  39     return 0;
  40 }
  41
  42 static int tak_parse(AVCodecParserContext *s, AVCodecContext *avctx,
  43                      const uint8_t **poutbuf, int *poutbuf_size,
  44                      const uint8_t *buf, int buf_size)
  45 {
  46     TAKParseContext *t = s->priv_data;
  47     ParseContext *pc   = &t->pc;
  48     int next           = END_NOT_FOUND;
  49     GetBitContext gb;
  50     int consumed = 0;
  51     int needed   = buf_size ? TAK_MAX_FRAME_HEADER_BYTES : 8;
  52
  53     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  54         TAKStreamInfo ti;
  55         init_get_bits(&gb, buf, buf_size);
  56         if (!ff_tak_decode_frame_header(avctx, &gb, &ti, 127))
  57             s->duration = t->ti.last_frame_samples ? t->ti.last_frame_samples
  58                                                    : t->ti.frame_samples;
  59         *poutbuf      = buf;
  60         *poutbuf_size = buf_size;
  61         return buf_size;
  62     }
  63
  64     while (buf_size || t->index + needed <= pc->index) {
  65         if (buf_size && t->index + TAK_MAX_FRAME_HEADER_BYTES > pc->index) {
  66             int tmp_buf_size       = FFMIN(2 * TAK_MAX_FRAME_HEADER_BYTES,
  67                                            buf_size);
  68             const uint8_t *tmp_buf = buf;
  69
  70             ff_combine_frame(pc, END_NOT_FOUND, &tmp_buf, &tmp_buf_size);
  71             consumed += tmp_buf_size;
  72             buf      += tmp_buf_size;
  73             buf_size -= tmp_buf_size;
  74         }
  75
  76         for (; t->index + needed <= pc->index; t->index++)
  77             if (pc->buffer[t->index]     == 0xFF &&
  78                 pc->buffer[t->index + 1] == 0xA0) {
  79                 TAKStreamInfo ti;
  80
  81                 init_get_bits(&gb, pc->buffer + t->index,
  82                               8 * (pc->index - t->index));
  83                 if (!ff_tak_decode_frame_header(avctx, &gb,
  84                                                 pc->frame_start_found ? &ti
  85                                                                       : &t->ti,
  86                                                 127) &&
  87                     !ff_tak_check_crc(pc->buffer + t->index,
  88                                       get_bits_count(&gb) / 8)) {
  89                     if (!pc->frame_start_found) {
  90                         pc->frame_start_found = 1;
  91                         s->duration           = t->ti.last_frame_samples ?
  92                                                 t->ti.last_frame_samples :
  93                                                 t->ti.frame_samples;
  94                     } else {
  95                         pc->frame_start_found = 0;
  96                         next                  = t->index - pc->index;
  97                         t->index              = 0;
  98                         goto found;
  99                     }
 100                 }
 101             }
 102     }
 103
 104 found:
 105     if (consumed && !buf_size && next == END_NOT_FOUND ||
 106         ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 107         *poutbuf      = NULL;
 108         *poutbuf_size = 0;
 109         return buf_size + consumed;
 110     }
 111
 112     if (next != END_NOT_FOUND) {
 113         next        += consumed;
 114         pc->overread = FFMAX(0, -next);
 115     }
 116
 117     *poutbuf      = buf;
 118     *poutbuf_size = buf_size;
 119     return next;
 120 }
 121
 122 AVCodecParser ff_tak_parser = {
 123     .codec_ids      = { AV_CODEC_ID_TAK },
 124     .priv_data_size = sizeof(TAKParseContext),
 125     .parser_init    = tak_init,
 126     .parser_parse   = tak_parse,
 127     .parser_close   = ff_parse_close,
 128 };