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FFmpeg/libavcodec/midivid.c
Andreas Rheinhardt 20f9727018 avcodec/codec_internal: Add FFCodec, hide internal part of AVCodec 
Up until now, codec.h contains both public and private parts
of AVCodec. This exposes the internals of AVCodec to users
and leads them into the temptation of actually using them
and forces us to forward-declare structures and types that
users can't use at all.

This commit changes this by adding a new structure FFCodec to
codec_internal.h that extends AVCodec, i.e. contains the public
AVCodec as first member; the private fields of AVCodec are moved
to this structure, leaving codec.h clean.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-03-21 01:33:09 +01:00

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/*
* MidiVid decoder
* Copyright (c) 2019 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libavutil/imgutils.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#define BITSTREAM_READER_LE
#include "avcodec.h"
#include "get_bits.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "internal.h"
typedef struct MidiVidContext {
GetByteContext gb;
uint8_t *uncompressed;
unsigned int uncompressed_size;
uint8_t *skip;
AVFrame *frame;
} MidiVidContext;
static int decode_mvdv(MidiVidContext *s, AVCodecContext *avctx, AVFrame *frame)
{
GetByteContext *gb = &s->gb;
GetBitContext mask;
GetByteContext idx9;
uint16_t nb_vectors, intra_flag;
const uint8_t *vec;
const uint8_t *mask_start;
uint8_t *skip;
uint32_t mask_size;
int idx9bits = 0;
int idx9val = 0;
uint32_t nb_blocks;
nb_vectors = bytestream2_get_le16(gb);
intra_flag = !!bytestream2_get_le16(gb);
if (intra_flag) {
nb_blocks = (avctx->width / 2) * (avctx->height / 2);
} else {
int ret, skip_linesize, padding;
nb_blocks = bytestream2_get_le32(gb);
skip_linesize = avctx->width >> 1;
mask_start = gb->buffer_start + bytestream2_tell(gb);
mask_size = (FFALIGN(avctx->width, 32) >> 2) * (avctx->height >> 2) >> 3;
padding = (FFALIGN(avctx->width, 32) - avctx->width) >> 2;
if (bytestream2_get_bytes_left(gb) < mask_size)
return AVERROR_INVALIDDATA;
ret = init_get_bits8(&mask, mask_start, mask_size);
if (ret < 0)
return ret;
bytestream2_skip(gb, mask_size);
skip = s->skip;
for (int y = 0; y < avctx->height >> 2; y++) {
for (int x = 0; x < avctx->width >> 2; x++) {
int flag = !get_bits1(&mask);
skip[(y*2) *skip_linesize + x*2 ] = flag;
skip[(y*2) *skip_linesize + x*2+1] = flag;
skip[(y*2+1)*skip_linesize + x*2 ] = flag;
skip[(y*2+1)*skip_linesize + x*2+1] = flag;
}
skip_bits_long(&mask, padding);
}
}
vec = gb->buffer_start + bytestream2_tell(gb);
if (bytestream2_get_bytes_left(gb) < nb_vectors * 12)
return AVERROR_INVALIDDATA;
bytestream2_skip(gb, nb_vectors * 12);
if (nb_vectors > 256) {
if (bytestream2_get_bytes_left(gb) < (nb_blocks + 7 * !intra_flag) / 8)
return AVERROR_INVALIDDATA;
bytestream2_init(&idx9, gb->buffer_start + bytestream2_tell(gb), (nb_blocks + 7 * !intra_flag) / 8);
bytestream2_skip(gb, (nb_blocks + 7 * !intra_flag) / 8);
}
skip = s->skip;
for (int y = avctx->height - 2; y >= 0; y -= 2) {
uint8_t *dsty = frame->data[0] + y * frame->linesize[0];
uint8_t *dstu = frame->data[1] + y * frame->linesize[1];
uint8_t *dstv = frame->data[2] + y * frame->linesize[2];
for (int x = 0; x < avctx->width; x += 2) {
int idx;
if (!intra_flag && *skip++)
continue;
if (bytestream2_get_bytes_left(gb) <= 0)
return AVERROR_INVALIDDATA;
if (nb_vectors <= 256) {
idx = bytestream2_get_byte(gb);
} else {
if (idx9bits == 0) {
idx9val = bytestream2_get_byte(&idx9);
idx9bits = 8;
}
idx9bits--;
idx = bytestream2_get_byte(gb) | (((idx9val >> (7 - idx9bits)) & 1) << 8);
}
if (idx >= nb_vectors)
return AVERROR_INVALIDDATA;
dsty[x +frame->linesize[0]] = vec[idx * 12 + 0];
dsty[x+1+frame->linesize[0]] = vec[idx * 12 + 3];
dsty[x] = vec[idx * 12 + 6];
dsty[x+1] = vec[idx * 12 + 9];
dstu[x +frame->linesize[1]] = vec[idx * 12 + 1];
dstu[x+1+frame->linesize[1]] = vec[idx * 12 + 4];
dstu[x] = vec[idx * 12 + 7];
dstu[x+1] = vec[idx * 12 +10];
dstv[x +frame->linesize[2]] = vec[idx * 12 + 2];
dstv[x+1+frame->linesize[2]] = vec[idx * 12 + 5];
dstv[x] = vec[idx * 12 + 8];
dstv[x+1] = vec[idx * 12 +11];
}
}
return intra_flag;
}
static ptrdiff_t lzss_uncompress(MidiVidContext *s, GetByteContext *gb, uint8_t *dst, unsigned int size)
{
uint8_t *dst_start = dst;
uint8_t *dst_end = dst + size;
for (;bytestream2_get_bytes_left(gb) >= 3;) {
int op = bytestream2_get_le16(gb);
for (int i = 0; i < 16; i++) {
if (op & 1) {
int s0 = bytestream2_get_byte(gb);
int s1 = bytestream2_get_byte(gb);
int offset = ((s0 & 0xF0) << 4) | s1;
int length = (s0 & 0xF) + 3;
if (dst + length > dst_end ||
dst - offset < dst_start)
return AVERROR_INVALIDDATA;
if (offset > 0) {
for (int j = 0; j < length; j++) {
dst[j] = dst[j - offset];
}
}
dst += length;
} else {
if (dst >= dst_end)
return AVERROR_INVALIDDATA;
*dst++ = bytestream2_get_byte(gb);
}
op >>= 1;
}
}
return dst - dst_start;
}
static int decode_frame(AVCodecContext *avctx, void *data,
int *got_frame, AVPacket *avpkt)
{
MidiVidContext *s = avctx->priv_data;
GetByteContext *gb = &s->gb;
AVFrame *frame = s->frame;
int ret, key, uncompressed;
if (avpkt->size <= 13)
return AVERROR_INVALIDDATA;
bytestream2_init(gb, avpkt->data, avpkt->size);
bytestream2_skip(gb, 8);
uncompressed = bytestream2_get_le32(gb);
if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)
return ret;
if (uncompressed) {
ret = decode_mvdv(s, avctx, frame);
} else {
av_fast_padded_malloc(&s->uncompressed, &s->uncompressed_size, 16LL * (avpkt->size - 12));
if (!s->uncompressed)
return AVERROR(ENOMEM);
ret = lzss_uncompress(s, gb, s->uncompressed, s->uncompressed_size);
if (ret < 0)
return ret;
bytestream2_init(gb, s->uncompressed, ret);
ret = decode_mvdv(s, avctx, frame);
}
if (ret < 0)
return ret;
key = ret;
if ((ret = av_frame_ref(data, s->frame)) < 0)
return ret;
frame->pict_type = key ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
frame->key_frame = key;
*got_frame = 1;
return avpkt->size;
}
static av_cold int decode_init(AVCodecContext *avctx)
{
MidiVidContext *s = avctx->priv_data;
int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
if (avctx->width & 3 || avctx->height & 3)
ret = AVERROR_INVALIDDATA;
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
avctx->width, avctx->height);
return ret;
}
avctx->pix_fmt = AV_PIX_FMT_YUV444P;
s->frame = av_frame_alloc();
if (!s->frame)
return AVERROR(ENOMEM);
s->skip = av_calloc(avctx->width >> 1, avctx->height >> 1);
if (!s->skip)
return AVERROR(ENOMEM);
return 0;
}
static void decode_flush(AVCodecContext *avctx)
{
MidiVidContext *s = avctx->priv_data;
av_frame_unref(s->frame);
}
static av_cold int decode_close(AVCodecContext *avctx)
{
MidiVidContext *s = avctx->priv_data;
av_frame_free(&s->frame);
av_freep(&s->uncompressed);
av_freep(&s->skip);
return 0;
}
const FFCodec ff_mvdv_decoder = {
.p.name = "mvdv",
.p.long_name = NULL_IF_CONFIG_SMALL("MidiVid VQ"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_MVDV,
.priv_data_size = sizeof(MidiVidContext),
.init = decode_init,
.decode = decode_frame,
.flush = decode_flush,
.close = decode_close,
.p.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
};
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