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 #define BITSTREAM_READER_LE
  28 #include "parser.h"
  29 #include "tak.h"
  30
  31 typedef struct TAKParseContext {
  32     ParseContext  pc;
  33     TAKStreamInfo ti;
  34     int           index;
  35 } TAKParseContext;
  36
  37 static av_cold int tak_init(AVCodecParserContext *s)
  38 {
  39     ff_tak_init_crc();
  40     return 0;
  41 }
  42
  43 static int tak_parse(AVCodecParserContext *s, AVCodecContext *avctx,
  44                      const uint8_t **poutbuf, int *poutbuf_size,
  45                      const uint8_t *buf, int buf_size)
  46 {
  47     TAKParseContext *t = s->priv_data;
  48     ParseContext *pc   = &t->pc;
  49     int next           = END_NOT_FOUND;
  50     GetBitContext gb;
  51     int consumed = 0;
  52     int needed   = buf_size ? TAK_MAX_FRAME_HEADER_BYTES : 8;
  53
  54     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  55         TAKStreamInfo ti;
  56         init_get_bits(&gb, buf, buf_size);
  57         if (!ff_tak_decode_frame_header(avctx, &gb, &ti, 127))
  58             s->duration = t->ti.last_frame_samples ? t->ti.last_frame_samples
  59                                                    : t->ti.frame_samples;
  60         *poutbuf      = buf;
  61         *poutbuf_size = buf_size;
  62         return buf_size;
  63     }
  64
  65     while (buf_size || t->index + needed <= pc->index) {
  66         if (buf_size && t->index + TAK_MAX_FRAME_HEADER_BYTES > pc->index) {
  67             int tmp_buf_size       = FFMIN(2 * TAK_MAX_FRAME_HEADER_BYTES,
  68                                            buf_size);
  69             const uint8_t *tmp_buf = buf;
  70
  71             ff_combine_frame(pc, END_NOT_FOUND, &tmp_buf, &tmp_buf_size);
  72             consumed += tmp_buf_size;
  73             buf      += tmp_buf_size;
  74             buf_size -= tmp_buf_size;
  75         }
  76
  77         for (; t->index + needed <= pc->index; t->index++)
  78             if (pc->buffer[t->index]     == 0xFF &&
  79                 pc->buffer[t->index + 1] == 0xA0) {
  80                 TAKStreamInfo ti;
  81
  82                 init_get_bits(&gb, pc->buffer + t->index,
  83                               8 * (pc->index - t->index));
  84                 if (!ff_tak_decode_frame_header(avctx, &gb,
  85                                                 pc->frame_start_found ? &ti
  86                                                                       : &t->ti,
  87                                                 127) &&
  88                     !ff_tak_check_crc(pc->buffer + t->index,
  89                                       get_bits_count(&gb) / 8)) {
  90                     if (!pc->frame_start_found) {
  91                         pc->frame_start_found = 1;
  92                         s->duration           = t->ti.last_frame_samples ?
  93                                                 t->ti.last_frame_samples :
  94                                                 t->ti.frame_samples;
  95                     } else {
  96                         pc->frame_start_found = 0;
  97                         next                  = t->index - pc->index;
  98                         t->index              = 0;
  99                         goto found;
 100                     }
 101                 }
 102             }
 103     }
 104
 105 found:
 106     if (consumed && !buf_size && next == END_NOT_FOUND ||
 107         ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 108         *poutbuf      = NULL;
 109         *poutbuf_size = 0;
 110         return buf_size + consumed;
 111     }
 112
 113     if (next != END_NOT_FOUND) {
 114         next        += consumed;
 115         pc->overread = FFMAX(0, -next);
 116     }
 117
 118     *poutbuf      = buf;
 119     *poutbuf_size = buf_size;
 120     return next;
 121 }
 122
 123 AVCodecParser ff_tak_parser = {
 124     .codec_ids      = { AV_CODEC_ID_TAK },
 125     .priv_data_size = sizeof(TAKParseContext),
 126     .parser_init    = tak_init,
 127     .parser_parse   = tak_parse,
 128     .parser_close   = ff_parse_close,
 129 };