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ffmpeg/libavformat/sga.c

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/*
* Digital Pictures SGA game demuxer
*
* Copyright (C) 2021 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 "libavutil/avassert.h"
#include "libavutil/internal.h"
#include "avformat.h"
#include "internal.h"
#include "avio_internal.h"
#define SEGA_CD_PCM_NUM 12500000
#define SEGA_CD_PCM_DEN 786432
typedef struct SGADemuxContext {
int video_stream_index;
int audio_stream_index;
uint8_t sector[65536 * 2];
int sector_headers;
int sample_rate;
int first_audio_size;
int payload_size;
int packet_type;
int flags;
int idx;
int left;
int64_t pkt_pos;
} SGADemuxContext;
static int sga_probe(const AVProbeData *p)
{
const uint8_t *src = p->buf;
int score = 0, sectors = 1;
int last_left = 0;
int sample_rate = -1;
if (p->buf_size < 2048)
return 0;
for (int i = 0; i + 2 < p->buf_size; i += 2048) {
int header = AV_RB16(src + i);
if ((header > 0x07FE && header < 0x8100) ||
(header > 0x8200 && header < 0xA100) ||
(header > 0xA200 && header < 0xC100)) {
sectors = 0;
break;
}
}
for (int i = 0; i + 4 < p->buf_size;) {
int header = AV_RB16(src + i);
int left = AV_RB16(src + i + 2);
int offset, type, size;
if (last_left < 0)
return 0;
if (sectors && header && last_left == 0) {
if (header >> 12) {
last_left = left;
} else {
last_left = left = header;
}
} else if (sectors && header) {
left = header;
last_left -= left;
if (header != 0x7FE && left < 7)
return 0;
} else if (sectors) {
if (left <= 8)
return 0;
i += sectors ? 2048 : left + 4;
last_left = 0;
continue;
}
if (sectors && (i > 0 && left < 0x7fe) &&
(i + left + 14 < p->buf_size)) {
offset = i + left + 2;
} else if (sectors && i > 0) {
i += 2048;
last_left -= FFMIN(last_left, 2046);
continue;
} else {
offset = 0;
last_left = left;
}
header = AV_RB16(src + offset);
size = AV_RB16(src + offset + 2) + 4;
while ((header & 0xFF00) == 0) {
offset++;
if (offset + 4 >= p->buf_size)
break;
header = AV_RB16(src + offset);
size = AV_RB16(src + offset + 2) + 4;
}
if (offset + 12 >= p->buf_size)
break;
if ((header & 0xFF) > 1)
return 0;
type = header >> 8;
if (type == 0xAA ||
type == 0xA1 ||
type == 0xA2 ||
type == 0xA3) {
int new_rate;
if (size <= 12)
return 0;
new_rate = AV_RB16(src + offset + 8);
if (sample_rate < 0)
sample_rate = new_rate;
if (sample_rate == 0 || new_rate != sample_rate)
return 0;
if (src[offset + 10] != 1)
return 0;
score += 10;
} else if (type == 0xC1 ||
type == 0xC6 ||
type == 0xC7 ||
type == 0xC8 ||
type == 0xC9 ||
type == 0xCB ||
type == 0xCD ||
type == 0xE7) {
int nb_pals = src[offset + 9];
int tiles_w = src[offset + 10];
int tiles_h = src[offset + 11];
if (size <= 12)
return 0;
if (nb_pals == 0 || nb_pals > 4)
return 0;
if (tiles_w == 0 || tiles_w > 80)
return 0;
if (tiles_h == 0 || tiles_h > 60)
return 0;
score += 10;
} else if (header == 0x7FE) {
;
} else {
return 0;
}
i += sectors ? 2048 : size + 4;
last_left -= FFMIN(last_left, 2046);
if (score < 0)
break;
}
return av_clip(score, 0, AVPROBE_SCORE_MAX);
}
static int sga_read_header(AVFormatContext *s)
{
SGADemuxContext *sga = s->priv_data;
AVIOContext *pb = s->pb;
sga->sector_headers = 1;
sga->first_audio_size = 0;
sga->video_stream_index = -1;
sga->audio_stream_index = -1;
sga->left = 2048;
sga->idx = 0;
s->ctx_flags |= AVFMTCTX_NOHEADER;
if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
while (!avio_feof(pb)) {
int header = avio_rb16(pb);
int type = header >> 8;
int skip = 2046;
int clock;
if (!sga->first_audio_size &&
(type == 0xAA ||
type == 0xA1 ||
type == 0xA2 ||
type == 0xA3)) {
sga->first_audio_size = avio_rb16(pb);
avio_skip(pb, 4);
clock = avio_rb16(pb);
sga->sample_rate = av_rescale(clock,
SEGA_CD_PCM_NUM,
SEGA_CD_PCM_DEN);
skip -= 8;
}
if ((header > 0x07FE && header < 0x8100) ||
(header > 0x8200 && header < 0xA100) ||
(header > 0xA200 && header < 0xC100)) {
sga->sector_headers = 0;
break;
}
avio_skip(pb, skip);
}
avio_seek(pb, 0, SEEK_SET);
}
return 0;
}
static void print_stats(AVFormatContext *s, const char *where)
{
SGADemuxContext *sga = s->priv_data;
av_log(s, AV_LOG_DEBUG, "START %s\n", where);
av_log(s, AV_LOG_DEBUG, "pos: %lX\n", avio_tell(s->pb));
av_log(s, AV_LOG_DEBUG, "idx: %X\n", sga->idx);
av_log(s, AV_LOG_DEBUG, "packet_type: %X\n", sga->packet_type);
av_log(s, AV_LOG_DEBUG, "payload_size: %X\n", sga->payload_size);
av_log(s, AV_LOG_DEBUG, "SECTOR: %016lX\n", AV_RB64(sga->sector));
av_log(s, AV_LOG_DEBUG, "stream: %X\n", sga->sector[1]);
av_log(s, AV_LOG_DEBUG, "END %s\n", where);
}
static void update_type_size(AVFormatContext *s)
{
SGADemuxContext *sga = s->priv_data;
if (sga->idx >= 4) {
sga->packet_type = sga->sector[0];
sga->payload_size = AV_RB16(sga->sector + 2);
} else {
sga->packet_type = 0;
sga->payload_size = 0;
}
}
static int sga_video_packet(AVFormatContext *s, AVPacket *pkt)
{
SGADemuxContext *sga = s->priv_data;
int ret;
if (sga->payload_size <= 8)
return AVERROR_INVALIDDATA;
if (sga->video_stream_index == -1) {
AVRational frame_rate;
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
st->start_time = 0;
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_tag = 0;
st->codecpar->codec_id = AV_CODEC_ID_SGA_VIDEO;
sga->video_stream_index = st->index;
if (sga->first_audio_size > 0 && sga->sample_rate > 0) {
frame_rate.num = sga->sample_rate;
frame_rate.den = sga->first_audio_size;
} else {
frame_rate.num = 15;
frame_rate.den = 1;
}
avpriv_set_pts_info(st, 64, frame_rate.den, frame_rate.num);
}
ret = av_new_packet(pkt, sga->payload_size + 4);
if (ret < 0)
return AVERROR(ENOMEM);
memcpy(pkt->data, sga->sector, sga->payload_size + 4);
av_assert0(sga->idx >= sga->payload_size + 4);
memmove(sga->sector, sga->sector + sga->payload_size + 4, sga->idx - sga->payload_size - 4);
pkt->stream_index = sga->video_stream_index;
pkt->duration = 1;
pkt->pos = sga->pkt_pos;
pkt->flags |= sga->flags;
sga->idx -= sga->payload_size + 4;
sga->flags = 0;
update_type_size(s);
av_log(s, AV_LOG_DEBUG, "VIDEO PACKET: %d:%016lX i:%X\n", pkt->size, AV_RB64(sga->sector), sga->idx);
return 0;
}
static int sga_audio_packet(AVFormatContext *s, AVPacket *pkt)
{
SGADemuxContext *sga = s->priv_data;
int ret;
if (sga->payload_size <= 8)
return AVERROR_INVALIDDATA;
if (sga->audio_stream_index == -1) {
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
st->start_time = 0;
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->codec_tag = 0;
st->codecpar->codec_id = AV_CODEC_ID_PCM_SGA;
st->codecpar->channels = 1;
st->codecpar->channel_layout= AV_CH_LAYOUT_MONO;
st->codecpar->sample_rate = av_rescale(AV_RB16(sga->sector + 8),
SEGA_CD_PCM_NUM,
SEGA_CD_PCM_DEN);
sga->audio_stream_index = st->index;
avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
}
ret = av_new_packet(pkt, sga->payload_size - 8);
if (ret < 0)
return AVERROR(ENOMEM);
memcpy(pkt->data, sga->sector + 12, sga->payload_size - 8);
av_assert0(sga->idx >= sga->payload_size + 4);
memmove(sga->sector, sga->sector + sga->payload_size + 4, sga->idx - sga->payload_size - 4);
pkt->stream_index = sga->audio_stream_index;
pkt->duration = pkt->size;
pkt->pos = sga->pkt_pos;
pkt->flags |= sga->flags;
sga->idx -= sga->payload_size + 4;
sga->flags = 0;
update_type_size(s);
av_log(s, AV_LOG_DEBUG, "AUDIO PACKET: %d:%016lX i:%X\n", pkt->size, AV_RB64(sga->sector), sga->idx);
return 0;
}
static int sga_packet(AVFormatContext *s, AVPacket *pkt)
{
SGADemuxContext *sga = s->priv_data;
int ret = 0;
if (sga->packet_type == 0xCD ||
sga->packet_type == 0xCB ||
sga->packet_type == 0xC9 ||
sga->packet_type == 0xC8 ||
sga->packet_type == 0xC7 ||
sga->packet_type == 0xC6 ||
sga->packet_type == 0xC1 ||
sga->packet_type == 0xE7) {
ret = sga_video_packet(s, pkt);
} else if (sga->packet_type == 0xA1 ||
sga->packet_type == 0xA2 ||
sga->packet_type == 0xA3 ||
sga->packet_type == 0xAA) {
ret = sga_audio_packet(s, pkt);
} else {
if (sga->idx == 0)
return AVERROR_EOF;
if (sga->sector[0])
return AVERROR_INVALIDDATA;
memmove(sga->sector, sga->sector + 1, sga->idx - 1);
sga->idx--;
return AVERROR(EAGAIN);
}
return ret;
}
static int try_packet(AVFormatContext *s, AVPacket *pkt)
{
SGADemuxContext *sga = s->priv_data;
int ret = AVERROR(EAGAIN);
update_type_size(s);
if (sga->idx >= sga->payload_size + 4) {
print_stats(s, "before sga_packet");
ret = sga_packet(s, pkt);
print_stats(s, "after sga_packet");
if (ret != AVERROR(EAGAIN))
return ret;
}
return sga->idx < sga->payload_size + 4 ? AVERROR(EAGAIN) : ret;
}
static int sga_read_packet(AVFormatContext *s, AVPacket *pkt)
{
SGADemuxContext *sga = s->priv_data;
AVIOContext *pb = s->pb;
int header, ret = 0;
sga->pkt_pos = avio_tell(pb);
retry:
update_type_size(s);
print_stats(s, "start");
if (avio_feof(pb) &&
(!sga->payload_size || sga->idx < sga->payload_size + 4))
return AVERROR_EOF;
if (sga->idx < sga->payload_size + 4) {
ret = ffio_ensure_seekback(pb, 2);
if (ret < 0)
return ret;
print_stats(s, "before read header");
header = avio_rb16(pb);
if (!header) {
avio_skip(pb, 2046);
sga->left = 0;
} else if (!avio_feof(pb) &&
((header >> 15) ||
!sga->sector_headers)) {
avio_seek(pb, -2, SEEK_CUR);
sga->flags = AV_PKT_FLAG_KEY;
sga->left = 2048;
} else {
sga->left = 2046;
}
av_assert0(sga->idx + sga->left < sizeof(sga->sector));
ret = avio_read(pb, sga->sector + sga->idx, sga->left);
if (ret > 0)
sga->idx += ret;
else if (ret != AVERROR_EOF && ret)
return ret;
print_stats(s, "after read header");
update_type_size(s);
}
ret = try_packet(s, pkt);
if (ret == AVERROR(EAGAIN))
goto retry;
return ret;
}
static int sga_seek(AVFormatContext *s, int stream_index,
int64_t timestamp, int flags)
{
SGADemuxContext *sga = s->priv_data;
sga->packet_type = sga->payload_size = sga->idx = 0;
memset(sga->sector, 0, sizeof(sga->sector));
return -1;
}
AVInputFormat ff_sga_demuxer = {
.name = "sga",
.long_name = NULL_IF_CONFIG_SMALL("Digital Pictures SGA"),
.priv_data_size = sizeof(SGADemuxContext),
.read_probe = sga_probe,
.read_header = sga_read_header,
.read_packet = sga_read_packet,
.read_seek = sga_seek,
.extensions = "sga",
.flags = AVFMT_GENERIC_INDEX,
};
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