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 "dca_parser.h"
00028 #include "get_bits.h"
00029 #include "put_bits.h"
00030 
00031 typedef struct DCAParseContext {
00032     ParseContext pc;
00033     uint32_t lastmarker;
00034     int size;
00035     int framesize;
00036     int hd_pos;
00037 } DCAParseContext;
00038 
00039 #define IS_MARKER(state, i, buf, buf_size) \
00040  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
00041  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
00042  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE || state == DCA_HD_MARKER)
00043 
00048 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
00049                               int buf_size)
00050 {
00051     int start_found, i;
00052     uint32_t state;
00053     ParseContext *pc = &pc1->pc;
00054 
00055     start_found = pc->frame_start_found;
00056     state = pc->state;
00057 
00058     i = 0;
00059     if (!start_found) {
00060         for (i = 0; i < buf_size; i++) {
00061             state = (state << 8) | buf[i];
00062             if (IS_MARKER(state, i, buf, buf_size)) {
00063                 if (!pc1->lastmarker || state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER) {
00064                     start_found = 1;
00065                     pc1->lastmarker = state;
00066                     break;
00067                 }
00068             }
00069         }
00070     }
00071     if (start_found) {
00072         for (; i < buf_size; i++) {
00073             pc1->size++;
00074             state = (state << 8) | buf[i];
00075             if (state == DCA_HD_MARKER && !pc1->hd_pos)
00076                 pc1->hd_pos = pc1->size;
00077             if (IS_MARKER(state, i, buf, buf_size) && (state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER)) {
00078                 if(pc1->framesize > pc1->size)
00079                     continue;
00080                 // 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.
00081                 if(!pc1->framesize && state == pc1->lastmarker && state != DCA_HD_MARKER){
00082                     pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
00083                 }
00084                 pc->frame_start_found = 0;
00085                 pc->state = -1;
00086                 pc1->size = 0;
00087                 return i - 3;
00088             }
00089         }
00090     }
00091     pc->frame_start_found = start_found;
00092     pc->state = state;
00093     return END_NOT_FOUND;
00094 }
00095 
00096 static av_cold int dca_parse_init(AVCodecParserContext * s)
00097 {
00098     DCAParseContext *pc1 = s->priv_data;
00099 
00100     pc1->lastmarker = 0;
00101     return 0;
00102 }
00103 
00104 int ff_dca_convert_bitstream(const uint8_t *src, int src_size, uint8_t *dst,
00105                              int max_size)
00106 {
00107     uint32_t mrk;
00108     int i, tmp;
00109     const uint16_t *ssrc = (const uint16_t *) src;
00110     uint16_t *sdst = (uint16_t *) dst;
00111     PutBitContext pb;
00112 
00113     if ((unsigned) src_size > (unsigned) max_size)
00114         src_size = max_size;
00115 
00116     mrk = AV_RB32(src);
00117     switch (mrk) {
00118     case DCA_MARKER_RAW_BE:
00119         memcpy(dst, src, src_size);
00120         return src_size;
00121     case DCA_MARKER_RAW_LE:
00122         for (i = 0; i < (src_size + 1) >> 1; i++)
00123             *sdst++ = av_bswap16(*ssrc++);
00124         return src_size;
00125     case DCA_MARKER_14B_BE:
00126     case DCA_MARKER_14B_LE:
00127         init_put_bits(&pb, dst, max_size);
00128         for (i = 0; i < (src_size + 1) >> 1; i++, src += 2) {
00129             tmp = ((mrk == DCA_MARKER_14B_BE) ? AV_RB16(src) : AV_RL16(src)) & 0x3FFF;
00130             put_bits(&pb, 14, tmp);
00131         }
00132         flush_put_bits(&pb);
00133         return (put_bits_count(&pb) + 7) >> 3;
00134     default:
00135         return AVERROR_INVALIDDATA;
00136     }
00137 }
00138 
00139 static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
00140                             int *sample_rate)
00141 {
00142     GetBitContext gb;
00143     uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
00144     int ret, sample_blocks, sr_code;
00145 
00146     if (buf_size < 12)
00147         return AVERROR_INVALIDDATA;
00148 
00149     if ((ret = ff_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
00150         return ret;
00151 
00152     init_get_bits(&gb, hdr, 96);
00153 
00154     skip_bits_long(&gb, 39);
00155     sample_blocks = get_bits(&gb, 7) + 1;
00156     if (sample_blocks < 8)
00157         return AVERROR_INVALIDDATA;
00158     *duration = 256 * (sample_blocks / 8);
00159 
00160     skip_bits(&gb, 20);
00161     sr_code = get_bits(&gb, 4);
00162     *sample_rate = avpriv_dca_sample_rates[sr_code];
00163     if (*sample_rate == 0)
00164         return AVERROR_INVALIDDATA;
00165 
00166     return 0;
00167 }
00168 
00169 static int dca_parse(AVCodecParserContext * s,
00170                      AVCodecContext * avctx,
00171                      const uint8_t ** poutbuf, int *poutbuf_size,
00172                      const uint8_t * buf, int buf_size)
00173 {
00174     DCAParseContext *pc1 = s->priv_data;
00175     ParseContext *pc = &pc1->pc;
00176     int next, duration, sample_rate;
00177 
00178     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
00179         next = buf_size;
00180     } else {
00181         next = dca_find_frame_end(pc1, buf, buf_size);
00182 
00183         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00184             *poutbuf = NULL;
00185             *poutbuf_size = 0;
00186             return buf_size;
00187         }
00188     }
00189 
00190     /* read the duration and sample rate from the frame header */
00191     if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {
00192         s->duration = duration;
00193         if (!avctx->sample_rate)
00194             avctx->sample_rate = sample_rate;
00195     } else
00196         s->duration = 0;
00197 
00198     *poutbuf = buf;
00199     *poutbuf_size = buf_size;
00200     return next;
00201 }
00202 
00203 AVCodecParser ff_dca_parser = {
00204     .codec_ids      = { AV_CODEC_ID_DTS },
00205     .priv_data_size = sizeof(DCAParseContext),
00206     .parser_init    = dca_parse_init,
00207     .parser_parse   = dca_parse,
00208     .parser_close   = ff_parse_close,
00209 };