libavcodec/dvaudiodec.c

   1 /*
   2  * Copyright (c) 2012 Laurent Aimar
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include "libavutil/channel_layout.h"
  22 #include "libavutil/intreadwrite.h"
  23 #include "avcodec.h"
  24 #include "codec_internal.h"
  25 #include "decode.h"
  26 #include "dvaudio.h"
  27
  28 typedef struct DVAudioContext {
  29     int block_size;
  30     int is_12bit;
  31     int is_pal;
  32     int16_t shuffle[2000];
  33 } DVAudioContext;
  34
  35 static av_cold int decode_init(AVCodecContext *avctx)
  36 {
  37     DVAudioContext *s = avctx->priv_data;
  38     int i;
  39
  40     if (avctx->codec_tag == 0x0215) {
  41         s->block_size = 7200;
  42     } else if (avctx->codec_tag == 0x0216) {
  43         s->block_size = 8640;
  44     } else if (avctx->block_align == 7200 ||
  45                avctx->block_align == 8640) {
  46         s->block_size = avctx->block_align;
  47     } else {
  48         return AVERROR(EINVAL);
  49     }
  50
  51     s->is_pal = s->block_size == 8640;
  52     s->is_12bit = avctx->bits_per_coded_sample == 12;
  53     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  54     av_channel_layout_uninit(&avctx->ch_layout);
  55     avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
  56
  57     for (i = 0; i < FF_ARRAY_ELEMS(s->shuffle); i++) {
  58         const unsigned a = s->is_pal ? 18 : 15;
  59         const unsigned b = 3 * a;
  60
  61         s->shuffle[i] = 80 * ((21 * (i % 3) + 9 * (i / 3) + ((i / a) % 3)) % b) +
  62                          (2 + s->is_12bit) * (i / b) + 8;
  63     }
  64
  65     return 0;
  66 }
  67
  68 static inline uint16_t dv_audio_12to16(uint16_t sample)
  69 {
  70     uint16_t shift, result;
  71
  72     sample = (sample < 0x800) ? sample : sample | 0xf000;
  73     shift  = (sample & 0xf00) >> 8;
  74
  75     if (shift < 0x2 || shift > 0xd) {
  76         result = sample;
  77     } else if (shift < 0x8) {
  78         shift--;
  79         result = (sample - (256 * shift)) << shift;
  80     } else {
  81         shift  = 0xe - shift;
  82         result = ((sample + ((256 * shift) + 1)) << shift) - 1;
  83     }
  84
  85     return result;
  86 }
  87
  88 static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
  89                         int *got_frame_ptr, AVPacket *pkt)
  90 {
  91     DVAudioContext *s = avctx->priv_data;
  92     const uint8_t *src = pkt->data;
  93     int16_t *dst;
  94     int ret, i;
  95
  96     if (pkt->size < s->block_size)
  97         return AVERROR_INVALIDDATA;
  98
  99     frame->nb_samples = dv_get_audio_sample_count(pkt->data + 244, s->is_pal);
 100     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 101         return ret;
 102     dst = (int16_t *)frame->data[0];
 103
 104     for (i = 0; i < frame->nb_samples; i++) {
 105        const uint8_t *v = &src[s->shuffle[i]];
 106
 107        if (s->is_12bit) {
 108            *dst++ = dv_audio_12to16((v[0] << 4) | ((v[2] >> 4) & 0x0f));
 109            *dst++ = dv_audio_12to16((v[1] << 4) | ((v[2] >> 0) & 0x0f));
 110        } else {
 111            *dst++ = AV_RB16(&v[0]);
 112            *dst++ = AV_RB16(&v[s->is_pal ? 4320 : 3600]);
 113        }
 114     }
 115
 116     *got_frame_ptr = 1;
 117
 118     return s->block_size;
 119 }
 120
 121 const FFCodec ff_dvaudio_decoder = {
 122     .p.name         = "dvaudio",
 123     CODEC_LONG_NAME("Ulead DV Audio"),
 124     .p.type         = AVMEDIA_TYPE_AUDIO,
 125     .p.id           = AV_CODEC_ID_DVAUDIO,
 126     .init           = decode_init,
 127     FF_CODEC_DECODE_CB(decode_frame),
 128     .p.capabilities = AV_CODEC_CAP_DR1,
 129     .priv_data_size = sizeof(DVAudioContext),
 130 };