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FFmpeg/libavcodec/vmixdec.c

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/*
* vMix decoder
* Copyright (c) 2023 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/intreadwrite.h"
#include "libavutil/mem_internal.h"
#include "avcodec.h"
#include "codec_internal.h"
#include "decode.h"
#define CACHED_BITSTREAM_READER !ARCH_X86_32
#include "golomb.h"
#include "get_bits.h"
#include "idctdsp.h"
#include "thread.h"
typedef struct SliceContext {
const uint8_t *dc_ptr;
const uint8_t *ac_ptr;
unsigned dc_size;
unsigned ac_size;
} SliceContext;
typedef struct VMIXContext {
int nb_slices;
int lshift;
int16_t factors[64];
uint8_t scan[64];
SliceContext *slices;
unsigned int slices_size;
IDCTDSPContext idsp;
} VMIXContext;
static const uint8_t quality[] = {
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1,64,63,62,61,
60,59,58,57,56,55,54,53,52,51,
50,49,48,47,46,45,44,43,42,41,
40,39,38,37,36,35,34,33,32,31,
30,29,28,27,26,25,24,23,22,21,
20,19,18,17,16,15,14,13,12,11,
10, 9, 8, 7, 6, 5, 4, 3, 2, 1,
};
static const uint8_t quant[64] = {
16, 16, 19, 22, 22, 26, 26, 27,
16, 16, 22, 22, 26, 27, 27, 29,
19, 22, 26, 26, 27, 29, 29, 35,
22, 24, 27, 27, 29, 32, 34, 38,
26, 27, 29, 29, 32, 35, 38, 46,
27, 29, 34, 34, 35, 40, 46, 56,
29, 34, 34, 37, 40, 48, 56, 69,
34, 37, 38, 40, 48, 58, 69, 83,
};
static av_cold int decode_init(AVCodecContext *avctx)
{
VMIXContext *s = avctx->priv_data;
avctx->bits_per_raw_sample = 8;
avctx->pix_fmt = AV_PIX_FMT_YUV422P;
avctx->coded_width = FFALIGN(avctx->width, 16);
avctx->coded_height = FFALIGN(avctx->height, 16);
ff_idctdsp_init(&s->idsp, avctx);
ff_permute_scantable(s->scan, ff_zigzag_direct,
s->idsp.idct_permutation);
return 0;
}
static inline int get_se_golomb_vmix(GetBitContext *gb)
{
unsigned int buf = get_ue_golomb_long(gb);
int sign = (buf & 1) - 1;
return ((buf >> 1) ^ (~sign));
}
static int decode_dcac(AVCodecContext *avctx,
GetBitContext *dc_gb, GetBitContext *ac_gb,
unsigned *dcrun, unsigned *acrun,
AVFrame *frame, int width, int by, int plane)
{
const ptrdiff_t linesize = frame->linesize[plane];
uint8_t *dst = frame->data[plane] + by * linesize;
unsigned dc_run = *dcrun, ac_run = *acrun;
LOCAL_ALIGNED_32(int16_t, block, [64]);
VMIXContext *s = avctx->priv_data;
const int16_t *factors = s->factors;
const uint8_t *scan = s->scan;
const int add = plane ? 0 : 1024;
int i, dc_v = 0, ac_v = 0, dc = 0;
const int lshift = s->lshift;
for (int y = 0; y < 2; y++) {
for (int x = 0; x < width; x += 8) {
memset(block, 0, sizeof(*block)*64);
if (dc_run > 0) {
dc_run--;
} else {
if (get_bits_left(dc_gb) < 1)
return AVERROR_INVALIDDATA;
dc_v = get_se_golomb_vmix(dc_gb);
dc += (unsigned)dc_v;
if (!dc_v)
dc_run = get_ue_golomb_long(dc_gb);
}
for (int n = 0; n < 64; n++) {
if (ac_run > 0) {
ac_run--;
continue;
}
if (get_bits_left(ac_gb) < 1)
return AVERROR_INVALIDDATA;
ac_v = get_se_golomb_vmix(ac_gb);
i = scan[n];
block[i] = ((unsigned)ac_v * factors[i]) >> 4;
if (!ac_v)
ac_run = get_ue_golomb_long(ac_gb);
}
block[0] = ((unsigned)dc << lshift) + (unsigned)add;
s->idsp.idct_put(dst + x, linesize, block);
}
dst += 8 * linesize;
}
*dcrun = dc_run;
*acrun = ac_run;
return 0;
}
static int decode_slice(AVCodecContext *avctx, AVFrame *frame,
const uint8_t *dc_src, unsigned dc_slice_size,
const uint8_t *ac_src, unsigned ac_slice_size,
int by)
{
unsigned dc_run = 0, ac_run = 0;
GetBitContext dc_gb, ac_gb;
int ret;
ret = init_get_bits8(&dc_gb, dc_src, dc_slice_size);
if (ret < 0)
return ret;
ret = init_get_bits8(&ac_gb, ac_src, ac_slice_size);
if (ret < 0)
return ret;
for (int p = 0; p < 3; p++) {
const int rshift = !!p;
ret = decode_dcac(avctx, &dc_gb, &ac_gb,
&dc_run, &ac_run, frame,
frame->width >> rshift, by, p);
if (ret < 0)
return ret;
if (get_bits_left(&dc_gb) < 0)
return AVERROR_INVALIDDATA;
if (get_bits_left(&ac_gb) < 0)
return AVERROR_INVALIDDATA;
align_get_bits(&dc_gb);
align_get_bits(&ac_gb);
}
if (get_bits_left(&dc_gb) > 0)
return AVERROR_INVALIDDATA;
if (get_bits_left(&ac_gb) > 0)
return AVERROR_INVALIDDATA;
return 0;
}
static int decode_slices(AVCodecContext *avctx, void *arg,
int n, int thread_nb)
{
VMIXContext *s = avctx->priv_data;
const uint8_t *dc_slice_ptr = s->slices[n].dc_ptr;
const uint8_t *ac_slice_ptr = s->slices[n].ac_ptr;
unsigned dc_slice_size = s->slices[n].dc_size;
unsigned ac_slice_size = s->slices[n].ac_size;
AVFrame *frame = arg;
return decode_slice(avctx, frame, dc_slice_ptr, dc_slice_size,
ac_slice_ptr, ac_slice_size, n * 16);
}
static int decode_frame(AVCodecContext *avctx,
AVFrame *frame, int *got_frame,
AVPacket *avpkt)
{
VMIXContext *s = avctx->priv_data;
unsigned offset, q;
int ret;
if (avpkt->size <= 7)
return AVERROR_INVALIDDATA;
s->lshift = 0;
offset = 2 + avpkt->data[0];
if (offset == 5)
s->lshift = avpkt->data[1];
else if (offset != 3)
return AVERROR_INVALIDDATA;
q = quality[FFMIN(avpkt->data[offset - 2], FF_ARRAY_ELEMS(quality)-1)];
for (int n = 0; n < 64; n++)
s->factors[n] = quant[n] * q;
s->nb_slices = (avctx->height + 15) / 16;
av_fast_mallocz(&s->slices, &s->slices_size, s->nb_slices * sizeof(*s->slices));
if (!s->slices)
return AVERROR(ENOMEM);
for (int n = 0; n < s->nb_slices; n++) {
unsigned slice_size;
if (offset + 4 > avpkt->size)
return AVERROR_INVALIDDATA;
slice_size = AV_RL32(avpkt->data + offset);
if (slice_size > avpkt->size)
return AVERROR_INVALIDDATA;
if (avpkt->size - slice_size - 4LL < offset)
return AVERROR_INVALIDDATA;
s->slices[n].dc_size = slice_size;
s->slices[n].dc_ptr = avpkt->data + offset + 4;
offset += slice_size + 4;
}
for (int n = 0; n < s->nb_slices; n++) {
unsigned slice_size;
if (offset + 4 > avpkt->size)
return AVERROR_INVALIDDATA;
slice_size = AV_RL32(avpkt->data + offset);
if (slice_size > avpkt->size)
return AVERROR_INVALIDDATA;
if (avpkt->size - slice_size - 4LL < offset)
return AVERROR_INVALIDDATA;
s->slices[n].ac_size = slice_size;
s->slices[n].ac_ptr = avpkt->data + offset + 4;
offset += slice_size + 4;
}
ret = ff_thread_get_buffer(avctx, frame, 0);
if (ret < 0)
return ret;
avctx->execute2(avctx, decode_slices, frame, NULL, s->nb_slices);
frame->pict_type = AV_PICTURE_TYPE_I;
frame->flags |= AV_FRAME_FLAG_KEY;
*got_frame = 1;
return avpkt->size;
}
static av_cold int decode_end(AVCodecContext *avctx)
{
VMIXContext *s = avctx->priv_data;
av_freep(&s->slices);
return 0;
}
const FFCodec ff_vmix_decoder = {
.p.name = "vmix",
CODEC_LONG_NAME("vMix Video"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_VMIX,
.priv_data_size = sizeof(VMIXContext),
.init = decode_init,
.close = decode_end,
FF_CODEC_DECODE_CB(decode_frame),
.p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS |
AV_CODEC_CAP_SLICE_THREADS,
};