ffmpeg/libavcodec/truehd_core_bsf.c

185 lines
5.0 KiB
C

/*
* Copyright (c) 2018 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 "avcodec.h"
#include "bsf.h"
#include "get_bits.h"
#include "mlp_parse.h"
#include "mlp.h"
typedef struct AccessUnit {
uint8_t bits[4];
uint16_t offset;
uint16_t optional;
} AccessUnit;
typedef struct TrueHDCoreContext {
const AVClass *class;
MLPHeaderInfo hdr;
} TrueHDCoreContext;
static int truehd_core_filter(AVBSFContext *ctx, AVPacket *pkt)
{
TrueHDCoreContext *s = ctx->priv_data;
GetBitContext gbc;
AccessUnit units[MAX_SUBSTREAMS];
int ret, i, last_offset = 0;
int in_size, out_size;
int have_header = 0;
int substream_bytes = 0;
int end;
ret = ff_bsf_get_packet_ref(ctx, pkt);
if (ret < 0)
return ret;
if (pkt->size < 4) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
in_size = (AV_RB16(pkt->data) & 0xFFF) * 2;
if (in_size < 4 || in_size > pkt->size) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
ret = init_get_bits8(&gbc, pkt->data + 4, pkt->size - 4);
if (ret < 0)
goto fail;
if (show_bits_long(&gbc, 32) == 0xf8726fba) {
if ((ret = ff_mlp_read_major_sync(ctx, &s->hdr, &gbc)) < 0)
goto fail;
have_header = 1;
}
if (s->hdr.num_substreams > MAX_SUBSTREAMS) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
for (i = 0; i < s->hdr.num_substreams; i++) {
for (int j = 0; j < 4; j++)
units[i].bits[j] = get_bits1(&gbc);
units[i].offset = get_bits(&gbc, 12);
if (i < 3) {
last_offset = units[i].offset * 2;
substream_bytes += 2;
}
if (units[i].bits[0]) {
units[i].optional = get_bits(&gbc, 16);
if (i < 3)
substream_bytes += 2;
}
}
end = get_bits_count(&gbc) >> 3;
out_size = end + 4 + last_offset;
if (out_size < in_size) {
int bpos = 0, reduce = end - have_header * 28 - substream_bytes;
uint16_t parity_nibble, dts = AV_RB16(pkt->data + 2);
uint16_t auheader;
uint8_t header[28];
av_assert1(reduce >= 0 && reduce % 2 == 0);
if (have_header) {
memcpy(header, pkt->data + 4, 28);
header[16] = (header[16] & 0x0c) | (FFMIN(s->hdr.num_substreams, 3) << 4);
header[17] &= 0x7f;
header[25] &= 0xfe;
AV_WL16(header + 26, ff_mlp_checksum16(header, 26));
}
pkt->data += reduce;
out_size -= reduce;
pkt->size = out_size;
ret = av_packet_make_writable(pkt);
if (ret < 0)
goto fail;
AV_WB16(pkt->data + 2, dts);
parity_nibble = dts;
parity_nibble ^= out_size / 2;
for (i = 0; i < FFMIN(s->hdr.num_substreams, 3); i++) {
uint16_t substr_hdr = 0;
substr_hdr |= (units[i].bits[0] << 15);
substr_hdr |= (units[i].bits[1] << 14);
substr_hdr |= (units[i].bits[2] << 13);
substr_hdr |= (units[i].bits[3] << 12);
substr_hdr |= units[i].offset;
AV_WB16(pkt->data + have_header * 28 + 4 + bpos, substr_hdr);
parity_nibble ^= substr_hdr;
bpos += 2;
if (units[i].bits[0]) {
AV_WB16(pkt->data + have_header * 28 + 4 + bpos, units[i].optional);
parity_nibble ^= units[i].optional;
bpos += 2;
}
}
parity_nibble ^= parity_nibble >> 8;
parity_nibble ^= parity_nibble >> 4;
parity_nibble &= 0xF;
auheader = (parity_nibble ^ 0xF) << 12;
auheader |= (out_size / 2) & 0x0fff;
AV_WB16(pkt->data, auheader);
if (have_header)
memcpy(pkt->data + 4, header, 28);
}
fail:
if (ret < 0)
av_packet_unref(pkt);
return ret;
}
static void truehd_core_flush(AVBSFContext *ctx)
{
TrueHDCoreContext *s = ctx->priv_data;
memset(&s->hdr, 0, sizeof(s->hdr));
}
static const enum AVCodecID codec_ids[] = {
AV_CODEC_ID_TRUEHD, AV_CODEC_ID_NONE,
};
const AVBitStreamFilter ff_truehd_core_bsf = {
.name = "truehd_core",
.priv_data_size = sizeof(TrueHDCoreContext),
.filter = truehd_core_filter,
.flush = truehd_core_flush,
.codec_ids = codec_ids,
};