FFmpeg: libavcodec/dca_parser.c Source File

00001 /*
00002  * DCA parser
00003  * Copyright (C) 2004 Gildas Bazin
00004  * Copyright (C) 2004 Benjamin Zores
00005  * Copyright (C) 2006 Benjamin Larsson
00006  * Copyright (C) 2007 Konstantin Shishkov
00007  *
00008  * This file is part of FFmpeg.
00009  *
00010  * FFmpeg is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * FFmpeg is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with FFmpeg; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 
00025 #include "parser.h"
00026 #include "dca.h"
00027 #include "dcadata.h"
00028 #include "dca_parser.h"
00029 #include "get_bits.h"
00030 #include "put_bits.h"
00031 
00032 typedef struct DCAParseContext {
00033     ParseContext pc;
00034     uint32_t lastmarker;
00035     int size;
00036     int framesize;
00037     int hd_pos;
00038 } DCAParseContext;
00039 
00040 #define IS_MARKER(state, i, buf, buf_size) \
00041  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
00042  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
00043  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE || state == DCA_HD_MARKER)
00044 
00049 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
00050                               int buf_size)
00051 {
00052     int start_found, i;
00053     uint32_t state;
00054     ParseContext *pc = &pc1->pc;
00055 
00056     start_found = pc->frame_start_found;
00057     state = pc->state;
00058 
00059     i = 0;
00060     if (!start_found) {
00061         for (i = 0; i < buf_size; i++) {
00062             state = (state << 8) | buf[i];
00063             if (IS_MARKER(state, i, buf, buf_size)) {
00064                 if (!pc1->lastmarker || state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER) {
00065                     start_found = 1;
00066                     pc1->lastmarker = state;
00067                     break;
00068                 }
00069             }
00070         }
00071     }
00072     if (start_found) {
00073         for (; i < buf_size; i++) {
00074             pc1->size++;
00075             state = (state << 8) | buf[i];
00076             if (state == DCA_HD_MARKER && !pc1->hd_pos)
00077                 pc1->hd_pos = pc1->size;
00078             if (IS_MARKER(state, i, buf, buf_size) && (state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER)) {
00079                 if(pc1->framesize > pc1->size)
00080                     continue;
00081                 // We have to check that we really read a full frame here, and that it isn't a pure HD frame, because their size is not constant.
00082                 if(!pc1->framesize && state == pc1->lastmarker && state != DCA_HD_MARKER){
00083                     pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
00084                 }
00085                 pc->frame_start_found = 0;
00086                 pc->state = -1;
00087                 pc1->size = 0;
00088                 return i - 3;
00089             }
00090         }
00091     }
00092     pc->frame_start_found = start_found;
00093     pc->state = state;
00094     return END_NOT_FOUND;
00095 }
00096 
00097 static av_cold int dca_parse_init(AVCodecParserContext * s)
00098 {
00099     DCAParseContext *pc1 = s->priv_data;
00100 
00101     pc1->lastmarker = 0;
00102     return 0;
00103 }
00104 
00105 int ff_dca_convert_bitstream(const uint8_t *src, int src_size, uint8_t *dst,
00106                              int max_size)
00107 {
00108     uint32_t mrk;
00109     int i, tmp;
00110     const uint16_t *ssrc = (const uint16_t *) src;
00111     uint16_t *sdst = (uint16_t *) dst;
00112     PutBitContext pb;
00113 
00114     if ((unsigned) src_size > (unsigned) max_size)
00115         src_size = max_size;
00116 
00117     mrk = AV_RB32(src);
00118     switch (mrk) {
00119     case DCA_MARKER_RAW_BE:
00120         memcpy(dst, src, src_size);
00121         return src_size;
00122     case DCA_MARKER_RAW_LE:
00123         for (i = 0; i < (src_size + 1) >> 1; i++)
00124             *sdst++ = av_bswap16(*ssrc++);
00125         return src_size;
00126     case DCA_MARKER_14B_BE:
00127     case DCA_MARKER_14B_LE:
00128         init_put_bits(&pb, dst, max_size);
00129         for (i = 0; i < (src_size + 1) >> 1; i++, src += 2) {
00130             tmp = ((mrk == DCA_MARKER_14B_BE) ? AV_RB16(src) : AV_RL16(src)) & 0x3FFF;
00131             put_bits(&pb, 14, tmp);
00132         }
00133         flush_put_bits(&pb);
00134         return (put_bits_count(&pb) + 7) >> 3;
00135     default:
00136         return AVERROR_INVALIDDATA;
00137     }
00138 }
00139 
00140 static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
00141                             int *sample_rate)
00142 {
00143     GetBitContext gb;
00144     uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
00145     int ret, sample_blocks, sr_code;
00146 
00147     if (buf_size < 12)
00148         return AVERROR_INVALIDDATA;
00149 
00150     if ((ret = ff_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
00151         return ret;
00152 
00153     init_get_bits(&gb, hdr, 96);
00154 
00155     skip_bits_long(&gb, 39);
00156     sample_blocks = get_bits(&gb, 7) + 1;
00157     if (sample_blocks < 8)
00158         return AVERROR_INVALIDDATA;
00159     *duration = 256 * (sample_blocks / 8);
00160 
00161     skip_bits(&gb, 20);
00162     sr_code = get_bits(&gb, 4);
00163     *sample_rate = dca_sample_rates[sr_code];
00164     if (*sample_rate == 0)
00165         return AVERROR_INVALIDDATA;
00166 
00167     return 0;
00168 }
00169 
00170 static int dca_parse(AVCodecParserContext * s,
00171                      AVCodecContext * avctx,
00172                      const uint8_t ** poutbuf, int *poutbuf_size,
00173                      const uint8_t * buf, int buf_size)
00174 {
00175     DCAParseContext *pc1 = s->priv_data;
00176     ParseContext *pc = &pc1->pc;
00177     int next, duration, sample_rate;
00178 
00179     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
00180         next = buf_size;
00181     } else {
00182         next = dca_find_frame_end(pc1, buf, buf_size);
00183 
00184         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00185             *poutbuf = NULL;
00186             *poutbuf_size = 0;
00187             return buf_size;
00188         }
00189     }
00190 
00191     /* read the duration and sample rate from the frame header */
00192     if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {
00193         s->duration = duration;
00194         if (!avctx->sample_rate)
00195             avctx->sample_rate = sample_rate;
00196     } else
00197         s->duration = 0;
00198 
00199     *poutbuf = buf;
00200     *poutbuf_size = buf_size;
00201     return next;
00202 }
00203 
00204 AVCodecParser ff_dca_parser = {
00205     .codec_ids      = { CODEC_ID_DTS },
00206     .priv_data_size = sizeof(DCAParseContext),
00207     .parser_init    = dca_parse_init,
00208     .parser_parse   = dca_parse,
00209     .parser_close   = ff_parse_close,
00210 };