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/*
* MIDI Sample Dump Standard format demuxer
* Copyright (c) 2017 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "internal.h"
typedef struct SDSContext {
uint8_t data[120];
int bit_depth;
int size;
void (*read_block)(const uint8_t *src, uint32_t *dst);
} SDSContext;
static int sds_probe(AVProbeData *p)
{
if (AV_RB32(p->buf) == 0xF07E0001 && p->buf[20] == 0xF7 &&
p->buf[6] >= 8 && p->buf[6] <= 28)
return AVPROBE_SCORE_EXTENSION;
return 0;
}
static void byte2_read(const uint8_t *src, uint32_t *dst)
{
int i;
for (i = 0; i < 120; i += 2) {
unsigned sample = (src[i + 0] << 25) + (src[i + 1] << 18);
dst[i / 2] = sample;
}
}
static void byte3_read(const uint8_t *src, uint32_t *dst)
{
int i;
for (i = 0; i < 120; i += 3) {
unsigned sample;
sample = (src[i + 0] << 25) | (src[i + 1] << 18) | (src[i + 2] << 11);
dst[i / 3] = sample;
}
}
static void byte4_read(const uint8_t *src, uint32_t *dst)
{
int i;
for (i = 0; i < 120; i += 4) {
unsigned sample;
sample = (src[i + 0] << 25) | (src[i + 1] << 18) | (src[i + 2] << 11) | (src[i + 3] << 4);
dst[i / 4] = sample;
}
}
#define SDS_3BYTE_TO_INT_DECODE(x) (((x) & 0x7F) | (((x) & 0x7F00) >> 1) | (((x) & 0x7F0000) >> 2))
static int sds_read_header(AVFormatContext *ctx)
{
SDSContext *s = ctx->priv_data;
unsigned sample_period;
AVIOContext *pb = ctx->pb;
AVStream *st;
st = avformat_new_stream(ctx, NULL);
if (!st)
return AVERROR(ENOMEM);
avio_skip(pb, 4);
avio_skip(pb, 2);
s->bit_depth = avio_r8(pb);
if (s->bit_depth < 8 || s->bit_depth > 28)
return AVERROR_INVALIDDATA;
if (s->bit_depth < 14) {
s->read_block = byte2_read;
s->size = 60 * 4;
} else if (s->bit_depth < 21) {
s->read_block = byte3_read;
s->size = 40 * 4;
} else {
s->read_block = byte4_read;
s->size = 30 * 4;
}
st->codecpar->codec_id = AV_CODEC_ID_PCM_U32LE;
sample_period = avio_rl24(pb);
sample_period = SDS_3BYTE_TO_INT_DECODE(sample_period);
avio_skip(pb, 11);
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->channels = 1;
st->codecpar->sample_rate = sample_period ? 1000000000 / sample_period : 16000;
st->duration = av_rescale((avio_size(pb) - 21) / 127, s->size, 4);
avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
return 0;
}
static int sds_read_packet(AVFormatContext *ctx, AVPacket *pkt)
{
SDSContext *s = ctx->priv_data;
AVIOContext *pb = ctx->pb;
int64_t pos;
int ret;
if (avio_feof(pb))
return AVERROR_EOF;
pos = avio_tell(pb);
if (avio_rb16(pb) != 0xF07E)
return AVERROR_INVALIDDATA;
avio_skip(pb, 3);
ret = av_new_packet(pkt, s->size);
if (ret < 0)
return ret;
ret = avio_read(pb, s->data, 120);
s->read_block(s->data, (uint32_t *)pkt->data);
avio_skip(pb, 1); // checksum
if (avio_r8(pb) != 0xF7)
return AVERROR_INVALIDDATA;
pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
pkt->stream_index = 0;
pkt->pos = pos;
return ret;
}
AVInputFormat ff_sds_demuxer = {
.name = "sds",
.long_name = NULL_IF_CONFIG_SMALL("MIDI Sample Dump Standard"),
.priv_data_size = sizeof(SDSContext),
.read_probe = sds_probe,
.read_header = sds_read_header,
.read_packet = sds_read_packet,
.extensions = "sds",
.flags = AVFMT_GENERIC_INDEX,
};
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