libavformat/sdsdec.c

   1 /*
   2  * MIDI Sample Dump Standard format demuxer
   3  * Copyright (c) 2017 Paul B Mahol
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/intreadwrite.h"
  23 #include "avformat.h"
  24 #include "internal.h"
  25
  26 typedef struct SDSContext {
  27     uint8_t data[120];
  28     int bit_depth;
  29     int size;
  30     void (*read_block)(const uint8_t *src, uint32_t *dst);
  31 } SDSContext;
  32
  33 static int sds_probe(const AVProbeData *p)
  34 {
  35     if (AV_RB32(p->buf) == 0xF07E0001 && p->buf[20] == 0xF7 &&
  36         p->buf[6] >= 8 && p->buf[6] <= 28)
  37         return AVPROBE_SCORE_EXTENSION;
  38     return 0;
  39 }
  40
  41 static void byte2_read(const uint8_t *src, uint32_t *dst)
  42 {
  43     int i;
  44
  45     for (i = 0; i < 120; i += 2) {
  46         unsigned sample = ((unsigned)src[i + 0] << 25) + ((unsigned)src[i + 1] << 18);
  47
  48         dst[i / 2] = sample;
  49     }
  50 }
  51
  52 static void byte3_read(const uint8_t *src, uint32_t *dst)
  53 {
  54     int i;
  55
  56     for (i = 0; i < 120; i += 3) {
  57         unsigned sample;
  58
  59         sample = ((unsigned)src[i + 0] << 25) | ((unsigned)src[i + 1] << 18) | ((unsigned)src[i + 2] << 11);
  60         dst[i / 3] = sample;
  61     }
  62 }
  63
  64 static void byte4_read(const uint8_t *src, uint32_t *dst)
  65 {
  66     int i;
  67
  68     for (i = 0; i < 120; i += 4) {
  69         unsigned sample;
  70
  71         sample = ((unsigned)src[i + 0] << 25) | ((unsigned)src[i + 1] << 18) | ((unsigned)src[i + 2] << 11) | ((unsigned)src[i + 3] << 4);
  72         dst[i / 4] = sample;
  73     }
  74 }
  75
  76 #define SDS_3BYTE_TO_INT_DECODE(x) (((x) & 0x7F) | (((x) & 0x7F00) >> 1) | (((x) & 0x7F0000) >> 2))
  77
  78 static int sds_read_header(AVFormatContext *ctx)
  79 {
  80     SDSContext *s = ctx->priv_data;
  81     unsigned sample_period;
  82     AVIOContext *pb = ctx->pb;
  83     AVStream *st;
  84
  85     st = avformat_new_stream(ctx, NULL);
  86     if (!st)
  87         return AVERROR(ENOMEM);
  88
  89     avio_skip(pb, 4);
  90     avio_skip(pb, 2);
  91
  92     s->bit_depth = avio_r8(pb);
  93     if (s->bit_depth < 8 || s->bit_depth > 28)
  94         return AVERROR_INVALIDDATA;
  95
  96     if (s->bit_depth < 14) {
  97         s->read_block = byte2_read;
  98         s->size = 60 * 4;
  99     } else if (s->bit_depth < 21) {
 100         s->read_block = byte3_read;
 101         s->size = 40 * 4;
 102     } else {
 103         s->read_block = byte4_read;
 104         s->size = 30 * 4;
 105     }
 106     st->codecpar->codec_id = AV_CODEC_ID_PCM_U32LE;
 107
 108     sample_period = avio_rl24(pb);
 109     sample_period = SDS_3BYTE_TO_INT_DECODE(sample_period);
 110     avio_skip(pb, 11);
 111
 112     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 113     st->codecpar->channels = 1;
 114     st->codecpar->sample_rate = sample_period ? 1000000000 / sample_period : 16000;
 115     st->duration = av_rescale((avio_size(pb) - 21) / 127,  s->size, 4);
 116
 117     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
 118
 119     return 0;
 120 }
 121
 122 static int sds_read_packet(AVFormatContext *ctx, AVPacket *pkt)
 123 {
 124     SDSContext *s = ctx->priv_data;
 125     AVIOContext *pb = ctx->pb;
 126     int64_t pos;
 127     int ret;
 128
 129     if (avio_feof(pb))
 130         return AVERROR_EOF;
 131
 132     pos = avio_tell(pb);
 133     if (avio_rb16(pb) != 0xF07E)
 134         return AVERROR_INVALIDDATA;
 135     avio_skip(pb, 3);
 136
 137     ret = av_new_packet(pkt, s->size);
 138     if (ret < 0)
 139         return ret;
 140
 141     ret = avio_read(pb, s->data, 120);
 142
 143     s->read_block(s->data, (uint32_t *)pkt->data);
 144
 145     avio_skip(pb, 1); // checksum
 146     if (avio_r8(pb) != 0xF7)
 147         return AVERROR_INVALIDDATA;
 148
 149     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
 150     pkt->stream_index = 0;
 151     pkt->pos = pos;
 152
 153     return ret;
 154 }
 155
 156 AVInputFormat ff_sds_demuxer = {
 157     .name           = "sds",
 158     .long_name      = NULL_IF_CONFIG_SMALL("MIDI Sample Dump Standard"),
 159     .priv_data_size = sizeof(SDSContext),
 160     .read_probe     = sds_probe,
 161     .read_header    = sds_read_header,
 162     .read_packet    = sds_read_packet,
 163     .extensions     = "sds",
 164     .flags          = AVFMT_GENERIC_INDEX,
 165 };