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FFmpeg/libavcodec/mimic.c
Andreas Rheinhardt 5975bb7f81 avcodec/mimic: Only keep what is used from ScanTable 
Namely ScanTable.permutated.

Reviewed-by: Peter Ross <pross@xvid.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-10-24 00:47:09 +02:00

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/*
* Copyright (C) 2005 Ole André Vadla Ravnås <oleavr@gmail.com>
* Copyright (C) 2008 Ramiro Polla
*
* 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 <stdint.h>
#include "libavutil/mem_internal.h"
#include "libavutil/thread.h"
#include "avcodec.h"
#include "blockdsp.h"
#include "codec_internal.h"
#include "decode.h"
#include "get_bits.h"
#include "bytestream.h"
#include "bswapdsp.h"
#include "hpeldsp.h"
#include "idctdsp.h"
#include "thread.h"
#include "threadframe.h"
#define MIMIC_HEADER_SIZE 20
#define MIMIC_VLC_BITS 11
typedef struct MimicContext {
AVCodecContext *avctx;
int num_vblocks[3];
int num_hblocks[3];
void *swap_buf;
int swap_buf_size;
int cur_index;
int prev_index;
ThreadFrame frames [16];
DECLARE_ALIGNED(32, int16_t, dct_block)[64];
GetBitContext gb;
uint8_t permutated_scantable[64];
BlockDSPContext bdsp;
BswapDSPContext bbdsp;
HpelDSPContext hdsp;
IDCTDSPContext idsp;
/* Kept in the context so multithreading can have a constant to read from */
int next_cur_index;
int next_prev_index;
} MimicContext;
static VLC block_vlc;
static const uint8_t huffsyms[] = {
0x10, 0x20, 0x30, 0x00, 0x11, 0x40, 0x50, 0x12, 0x13, 0x21, 0x31, 0x60,
0x14, 0x15, 0x16, 0x22, 0x41, 0x17, 0x18, 0x23, 0x24, 0x25, 0x32, 0x42,
0x51, 0x61, 0x70, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x26, 0x27,
0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x33, 0x34, 0x35, 0x36, 0x37,
0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x43, 0x44, 0x45, 0x46, 0x47,
0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x52, 0x53, 0x54, 0x55, 0x56,
0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x62, 0x63, 0x64, 0x65,
0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x71, 0x72, 0x73,
0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E,
};
static const uint8_t huffbits[] = {
2, 2, 3, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8,
8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12,
13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17,
17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21,
22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26,
26, 26, 27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 29, 30, 30, 30,
};
static const uint8_t col_zag[64] = {
0, 8, 1, 2, 9, 16, 24, 17,
10, 3, 4, 11, 18, 25, 32, 40,
33, 26, 19, 12, 5, 6, 13, 20,
27, 34, 41, 48, 56, 49, 42, 35,
28, 21, 14, 7, 15, 22, 29, 36,
43, 50, 57, 58, 51, 44, 37, 30,
23, 31, 38, 45, 52, 59, 39, 46,
53, 60, 61, 54, 47, 55, 62, 63,
};
static av_cold int mimic_decode_end(AVCodecContext *avctx)
{
MimicContext *ctx = avctx->priv_data;
int i;
av_freep(&ctx->swap_buf);
ctx->swap_buf_size = 0;
for (i = 0; i < FF_ARRAY_ELEMS(ctx->frames); i++) {
if (ctx->frames[i].f)
ff_thread_release_ext_buffer(avctx, &ctx->frames[i]);
av_frame_free(&ctx->frames[i].f);
}
return 0;
}
static av_cold void mimic_init_static(void)
{
INIT_VLC_STATIC_FROM_LENGTHS(&block_vlc, MIMIC_VLC_BITS, FF_ARRAY_ELEMS(huffbits),
huffbits, 1, huffsyms, 1, 1, 0, 0, 4368);
}
static av_cold int mimic_decode_init(AVCodecContext *avctx)
{
static AVOnce init_static_once = AV_ONCE_INIT;
MimicContext *ctx = avctx->priv_data;
int i;
ctx->prev_index = 0;
ctx->cur_index = 15;
ff_blockdsp_init(&ctx->bdsp);
ff_bswapdsp_init(&ctx->bbdsp);
ff_hpeldsp_init(&ctx->hdsp, avctx->flags);
ff_idctdsp_init(&ctx->idsp, avctx);
ff_permute_scantable(ctx->permutated_scantable, col_zag, ctx->idsp.idct_permutation);
for (i = 0; i < FF_ARRAY_ELEMS(ctx->frames); i++) {
ctx->frames[i].f = av_frame_alloc();
if (!ctx->frames[i].f)
return AVERROR(ENOMEM);
}
ff_thread_once(&init_static_once, mimic_init_static);
return 0;
}
#if HAVE_THREADS
static int mimic_decode_update_thread_context(AVCodecContext *avctx, const AVCodecContext *avctx_from)
{
MimicContext *dst = avctx->priv_data, *src = avctx_from->priv_data;
int i, ret;
if (avctx == avctx_from)
return 0;
dst->cur_index = src->next_cur_index;
dst->prev_index = src->next_prev_index;
for (i = 0; i < FF_ARRAY_ELEMS(dst->frames); i++) {
ff_thread_release_ext_buffer(avctx, &dst->frames[i]);
if (i != src->next_cur_index && src->frames[i].f->data[0]) {
ret = ff_thread_ref_frame(&dst->frames[i], &src->frames[i]);
if (ret < 0)
return ret;
}
}
return 0;
}
#endif
static const int8_t vlcdec_lookup[9][64] = {
{ 0, },
{ -1, 1, },
{ -3, 3, -2, 2, },
{ -7, 7, -6, 6, -5, 5, -4, 4, },
{ -15, 15, -14, 14, -13, 13, -12, 12,
-11, 11, -10, 10, -9, 9, -8, 8, },
{ -31, 31, -30, 30, -29, 29, -28, 28,
-27, 27, -26, 26, -25, 25, -24, 24,
-23, 23, -22, 22, -21, 21, -20, 20,
-19, 19, -18, 18, -17, 17, -16, 16, },
{ -63, 63, -62, 62, -61, 61, -60, 60,
-59, 59, -58, 58, -57, 57, -56, 56,
-55, 55, -54, 54, -53, 53, -52, 52,
-51, 51, -50, 50, -49, 49, -48, 48,
-47, 47, -46, 46, -45, 45, -44, 44,
-43, 43, -42, 42, -41, 41, -40, 40,
-39, 39, -38, 38, -37, 37, -36, 36,
-35, 35, -34, 34, -33, 33, -32, 32, },
{ -127, 127, -126, 126, -125, 125, -124, 124,
-123, 123, -122, 122, -121, 121, -120, 120,
-119, 119, -118, 118, -117, 117, -116, 116,
-115, 115, -114, 114, -113, 113, -112, 112,
-111, 111, -110, 110, -109, 109, -108, 108,
-107, 107, -106, 106, -105, 105, -104, 104,
-103, 103, -102, 102, -101, 101, -100, 100,
-99, 99, -98, 98, -97, 97, -96, 96, },
{ -95, 95, -94, 94, -93, 93, -92, 92,
-91, 91, -90, 90, -89, 89, -88, 88,
-87, 87, -86, 86, -85, 85, -84, 84,
-83, 83, -82, 82, -81, 81, -80, 80,
-79, 79, -78, 78, -77, 77, -76, 76,
-75, 75, -74, 74, -73, 73, -72, 72,
-71, 71, -70, 70, -69, 69, -68, 68,
-67, 67, -66, 66, -65, 65, -64, 64, },
};
static int vlc_decode_block(MimicContext *ctx, int num_coeffs, int qscale)
{
int16_t *block = ctx->dct_block;
unsigned int pos;
ctx->bdsp.clear_block(block);
block[0] = get_bits(&ctx->gb, 8) << 3;
for (pos = 1; pos < num_coeffs; pos++) {
uint32_t vlc, num_bits;
int value;
int coeff;
vlc = get_vlc2(&ctx->gb, block_vlc.table, MIMIC_VLC_BITS, 3);
if (!vlc) /* end-of-block code */
return 0;
if (vlc == -1)
return AVERROR_INVALIDDATA;
/* pos_add and num_bits are coded in the vlc code */
pos += vlc & 15; // pos_add
num_bits = vlc >> 4; // num_bits
if (pos >= 64)
return AVERROR_INVALIDDATA;
value = get_bits(&ctx->gb, num_bits);
/* FFmpeg's IDCT behaves somewhat different from the original code, so
* a factor of 4 was added to the input */
coeff = ((int8_t*)vlcdec_lookup[num_bits])[value];
if (pos < 3)
coeff *= 16;
else /* TODO Use >> 10 instead of / 1001 */
coeff = (coeff * qscale) / 1001;
block[ctx->permutated_scantable[pos]] = coeff;
}
return 0;
}
static int decode(MimicContext *ctx, int quality, int num_coeffs,
int is_iframe)
{
int ret, y, x, plane, cur_row = 0;
for (plane = 0; plane < 3; plane++) {
const int is_chroma = !!plane;
const int qscale = av_clip(10000 - quality, is_chroma ? 1000 : 2000,
10000) << 2;
const int stride = ctx->frames[ctx->cur_index ].f->linesize[plane];
uint8_t *dst = ctx->frames[ctx->cur_index ].f->data[plane];
/* src is unused for I frames; set to avoid UB pointer arithmetic. */
const uint8_t *src = is_iframe ? dst : ctx->frames[ctx->prev_index].f->data[plane];
for (y = 0; y < ctx->num_vblocks[plane]; y++) {
for (x = 0; x < ctx->num_hblocks[plane]; x++) {
/* Check for a change condition in the current block.
* - iframes always change.
* - Luma plane changes on get_bits1 == 0
* - Chroma planes change on get_bits1 == 1 */
if (is_iframe || get_bits1(&ctx->gb) == is_chroma) {
/* Luma planes may use a backreference from the 15 last
* frames preceding the previous. (get_bits1 == 1)
* Chroma planes don't use backreferences. */
if (is_chroma || is_iframe || !get_bits1(&ctx->gb)) {
if ((ret = vlc_decode_block(ctx, num_coeffs,
qscale)) < 0) {
av_log(ctx->avctx, AV_LOG_ERROR, "Error decoding "
"block.\n");
return ret;
}
ctx->idsp.idct_put(dst, stride, ctx->dct_block);
} else {
unsigned int backref = get_bits(&ctx->gb, 4);
int index = (ctx->cur_index + backref) & 15;
uint8_t *p = ctx->frames[index].f->data[0];
if (index != ctx->cur_index && p) {
ff_thread_await_progress(&ctx->frames[index],
cur_row, 0);
p += src -
ctx->frames[ctx->prev_index].f->data[plane];
ctx->hdsp.put_pixels_tab[1][0](dst, p, stride, 8);
} else {
av_log(ctx->avctx, AV_LOG_ERROR,
"No such backreference! Buggy sample.\n");
}
}
} else {
ff_thread_await_progress(&ctx->frames[ctx->prev_index],
cur_row, 0);
ctx->hdsp.put_pixels_tab[1][0](dst, src, stride, 8);
}
src += 8;
dst += 8;
}
src += (stride - ctx->num_hblocks[plane]) << 3;
dst += (stride - ctx->num_hblocks[plane]) << 3;
ff_thread_report_progress(&ctx->frames[ctx->cur_index],
cur_row++, 0);
}
}
return 0;
}
/**
* Flip the buffer upside-down and put it in the YVU order to revert the
* way Mimic encodes frames.
*/
static void flip_swap_frame(AVFrame *f)
{
int i;
uint8_t *data_1 = f->data[1];
f->data[0] = f->data[0] + ( f->height - 1) * f->linesize[0];
f->data[1] = f->data[2] + ((f->height >> 1) - 1) * f->linesize[2];
f->data[2] = data_1 + ((f->height >> 1) - 1) * f->linesize[1];
for (i = 0; i < 3; i++)
f->linesize[i] *= -1;
}
static int mimic_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
int *got_frame, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
int swap_buf_size = buf_size - MIMIC_HEADER_SIZE;
MimicContext *ctx = avctx->priv_data;
GetByteContext gb;
int is_pframe;
int width, height;
int quality, num_coeffs;
int res;
if (buf_size <= MIMIC_HEADER_SIZE) {
av_log(avctx, AV_LOG_ERROR, "insufficient data\n");
return AVERROR_INVALIDDATA;
}
bytestream2_init(&gb, buf, MIMIC_HEADER_SIZE);
bytestream2_skip(&gb, 2); /* some constant (always 256) */
quality = bytestream2_get_le16u(&gb);
width = bytestream2_get_le16u(&gb);
height = bytestream2_get_le16u(&gb);
bytestream2_skip(&gb, 4); /* some constant */
is_pframe = bytestream2_get_le32u(&gb);
num_coeffs = bytestream2_get_byteu(&gb);
bytestream2_skip(&gb, 3); /* some constant */
if (!ctx->avctx) {
int i;
if (!(width == 160 && height == 120) &&
!(width == 320 && height == 240)) {
av_log(avctx, AV_LOG_ERROR, "invalid width/height!\n");
return AVERROR_INVALIDDATA;
}
res = ff_set_dimensions(avctx, width, height);
if (res < 0)
return res;
ctx->avctx = avctx;
avctx->pix_fmt = AV_PIX_FMT_YUV420P;
for (i = 0; i < 3; i++) {
ctx->num_vblocks[i] = AV_CEIL_RSHIFT(height, 3 + !!i);
ctx->num_hblocks[i] = width >> (3 + !!i);
}
} else if (width != ctx->avctx->width || height != ctx->avctx->height) {
avpriv_request_sample(avctx, "Resolution changing");
return AVERROR_PATCHWELCOME;
}
if (is_pframe && !ctx->frames[ctx->prev_index].f->data[0]) {
av_log(avctx, AV_LOG_ERROR, "decoding must start with keyframe\n");
return AVERROR_INVALIDDATA;
}
ff_thread_release_ext_buffer(avctx, &ctx->frames[ctx->cur_index]);
ctx->frames[ctx->cur_index].f->pict_type = is_pframe ? AV_PICTURE_TYPE_P :
AV_PICTURE_TYPE_I;
if ((res = ff_thread_get_ext_buffer(avctx, &ctx->frames[ctx->cur_index],
AV_GET_BUFFER_FLAG_REF)) < 0)
return res;
ctx->next_prev_index = ctx->cur_index;
ctx->next_cur_index = (ctx->cur_index - 1) & 15;
ff_thread_finish_setup(avctx);
av_fast_padded_malloc(&ctx->swap_buf, &ctx->swap_buf_size, swap_buf_size);
if (!ctx->swap_buf)
return AVERROR(ENOMEM);
ctx->bbdsp.bswap_buf(ctx->swap_buf,
(const uint32_t *) (buf + MIMIC_HEADER_SIZE),
swap_buf_size >> 2);
init_get_bits(&ctx->gb, ctx->swap_buf, swap_buf_size << 3);
res = decode(ctx, quality, num_coeffs, !is_pframe);
ff_thread_report_progress(&ctx->frames[ctx->cur_index], INT_MAX, 0);
if (res < 0) {
if (!(avctx->active_thread_type & FF_THREAD_FRAME))
ff_thread_release_ext_buffer(avctx, &ctx->frames[ctx->cur_index]);
return res;
}
if ((res = av_frame_ref(rframe, ctx->frames[ctx->cur_index].f)) < 0)
return res;
*got_frame = 1;
flip_swap_frame(rframe);
ctx->prev_index = ctx->next_prev_index;
ctx->cur_index = ctx->next_cur_index;
return buf_size;
}
const FFCodec ff_mimic_decoder = {
.p.name = "mimic",
CODEC_LONG_NAME("Mimic"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_MIMIC,
.priv_data_size = sizeof(MimicContext),
.init = mimic_decode_init,
.close = mimic_decode_end,
FF_CODEC_DECODE_CB(mimic_decode_frame),
.p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
UPDATE_THREAD_CONTEXT(mimic_decode_update_thread_context),
.caps_internal = FF_CODEC_CAP_ALLOCATE_PROGRESS |
FF_CODEC_CAP_INIT_CLEANUP,
};
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