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FFmpeg/libavcodec/msvideo1.c
Andreas Rheinhardt 4243da4ff4 avcodec/codec_internal: Use union for FFCodec decode/encode callbacks 
This is possible, because every given FFCodec has to implement
exactly one of these. Doing so decreases sizeof(FFCodec) and
therefore decreases the size of the binary.
Notice that in case of position-independent code the decrease
is in .data.rel.ro, so that this translates to decreased
memory consumption.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-04-05 20:02:37 +02:00

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/*
* Microsoft Video-1 Decoder
* Copyright (C) 2003 The FFmpeg project
*
* 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
*/
/**
* @file
* Microsoft Video-1 Decoder by Mike Melanson (melanson@pcisys.net)
* For more information about the MS Video-1 format, visit:
* http://www.pcisys.net/~melanson/codecs/
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#include "codec_internal.h"
#include "decode.h"
#include "internal.h"
#define PALETTE_COUNT 256
#define CHECK_STREAM_PTR(n) \
if ((stream_ptr + n) > s->size ) { \
av_log(s->avctx, AV_LOG_ERROR, " MS Video-1 warning: stream_ptr out of bounds (%d >= %d)\n", \
stream_ptr + n, s->size); \
return; \
}
typedef struct Msvideo1Context {
AVCodecContext *avctx;
AVFrame *frame;
const unsigned char *buf;
int size;
int mode_8bit; /* if it's not 8-bit, it's 16-bit */
uint32_t pal[256];
} Msvideo1Context;
static av_cold int msvideo1_decode_init(AVCodecContext *avctx)
{
Msvideo1Context *s = avctx->priv_data;
s->avctx = avctx;
if (avctx->width < 4 || avctx->height < 4)
return AVERROR_INVALIDDATA;
/* figure out the colorspace based on the presence of a palette */
if (s->avctx->bits_per_coded_sample == 8) {
s->mode_8bit = 1;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
if (avctx->extradata_size >= AVPALETTE_SIZE)
memcpy(s->pal, avctx->extradata, AVPALETTE_SIZE);
} else {
s->mode_8bit = 0;
avctx->pix_fmt = AV_PIX_FMT_RGB555;
}
s->frame = av_frame_alloc();
if (!s->frame)
return AVERROR(ENOMEM);
return 0;
}
static void msvideo1_decode_8bit(Msvideo1Context *s)
{
int block_ptr, pixel_ptr;
int total_blocks;
int pixel_x, pixel_y; /* pixel width and height iterators */
int block_x, block_y; /* block width and height iterators */
int blocks_wide, blocks_high; /* width and height in 4x4 blocks */
int block_inc;
int row_dec;
/* decoding parameters */
int stream_ptr;
unsigned char byte_a, byte_b;
unsigned short flags;
int skip_blocks;
unsigned char colors[8];
unsigned char *pixels = s->frame->data[0];
int stride = s->frame->linesize[0];
stream_ptr = 0;
skip_blocks = 0;
blocks_wide = s->avctx->width / 4;
blocks_high = s->avctx->height / 4;
total_blocks = blocks_wide * blocks_high;
block_inc = 4;
row_dec = stride + 4;
for (block_y = blocks_high; block_y > 0; block_y--) {
block_ptr = ((block_y * 4) - 1) * stride;
for (block_x = blocks_wide; block_x > 0; block_x--) {
/* check if this block should be skipped */
if (skip_blocks) {
block_ptr += block_inc;
skip_blocks--;
total_blocks--;
continue;
}
pixel_ptr = block_ptr;
/* get the next two bytes in the encoded data stream */
CHECK_STREAM_PTR(2);
byte_a = s->buf[stream_ptr++];
byte_b = s->buf[stream_ptr++];
/* check if the decode is finished */
if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0))
return;
else if ((byte_b & 0xFC) == 0x84) {
/* skip code, but don't count the current block */
skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
} else if (byte_b < 0x80) {
/* 2-color encoding */
flags = (byte_b << 8) | byte_a;
CHECK_STREAM_PTR(2);
colors[0] = s->buf[stream_ptr++];
colors[1] = s->buf[stream_ptr++];
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
pixel_ptr -= row_dec;
}
} else if (byte_b >= 0x90) {
/* 8-color encoding */
flags = (byte_b << 8) | byte_a;
CHECK_STREAM_PTR(8);
memcpy(colors, &s->buf[stream_ptr], 8);
stream_ptr += 8;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
pixels[pixel_ptr++] =
colors[((pixel_y & 0x2) << 1) +
(pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
pixel_ptr -= row_dec;
}
} else {
/* 1-color encoding */
colors[0] = byte_a;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++)
pixels[pixel_ptr++] = colors[0];
pixel_ptr -= row_dec;
}
}
block_ptr += block_inc;
total_blocks--;
}
}
/* make the palette available on the way out */
if (s->avctx->pix_fmt == AV_PIX_FMT_PAL8)
memcpy(s->frame->data[1], s->pal, AVPALETTE_SIZE);
}
static void msvideo1_decode_16bit(Msvideo1Context *s)
{
int block_ptr, pixel_ptr;
int total_blocks;
int pixel_x, pixel_y; /* pixel width and height iterators */
int block_x, block_y; /* block width and height iterators */
int blocks_wide, blocks_high; /* width and height in 4x4 blocks */
int block_inc;
int row_dec;
/* decoding parameters */
int stream_ptr;
unsigned char byte_a, byte_b;
unsigned short flags;
int skip_blocks;
unsigned short colors[8];
unsigned short *pixels = (unsigned short *)s->frame->data[0];
int stride = s->frame->linesize[0] / 2;
stream_ptr = 0;
skip_blocks = 0;
blocks_wide = s->avctx->width / 4;
blocks_high = s->avctx->height / 4;
total_blocks = blocks_wide * blocks_high;
block_inc = 4;
row_dec = stride + 4;
for (block_y = blocks_high; block_y > 0; block_y--) {
block_ptr = ((block_y * 4) - 1) * stride;
for (block_x = blocks_wide; block_x > 0; block_x--) {
/* check if this block should be skipped */
if (skip_blocks) {
block_ptr += block_inc;
skip_blocks--;
total_blocks--;
continue;
}
pixel_ptr = block_ptr;
/* get the next two bytes in the encoded data stream */
CHECK_STREAM_PTR(2);
byte_a = s->buf[stream_ptr++];
byte_b = s->buf[stream_ptr++];
/* check if the decode is finished */
if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0)) {
return;
} else if ((byte_b & 0xFC) == 0x84) {
/* skip code, but don't count the current block */
skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
} else if (byte_b < 0x80) {
/* 2- or 8-color encoding modes */
flags = (byte_b << 8) | byte_a;
CHECK_STREAM_PTR(4);
colors[0] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[1] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
if (colors[0] & 0x8000) {
/* 8-color encoding */
CHECK_STREAM_PTR(12);
colors[2] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[3] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[4] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[5] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[6] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
colors[7] = AV_RL16(&s->buf[stream_ptr]);
stream_ptr += 2;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
pixels[pixel_ptr++] =
colors[((pixel_y & 0x2) << 1) +
(pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
pixel_ptr -= row_dec;
}
} else {
/* 2-color encoding */
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
pixel_ptr -= row_dec;
}
}
} else {
/* otherwise, it's a 1-color block */
colors[0] = (byte_b << 8) | byte_a;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++)
pixels[pixel_ptr++] = colors[0];
pixel_ptr -= row_dec;
}
}
block_ptr += block_inc;
total_blocks--;
}
}
}
static int msvideo1_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
int *got_frame, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
Msvideo1Context *s = avctx->priv_data;
int ret;
s->buf = buf;
s->size = buf_size;
// Discard frame if its smaller than the minimum frame size
if (buf_size < (avctx->width/4) * (avctx->height/4) / 512) {
av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
return AVERROR_INVALIDDATA;
}
if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)
return ret;
if (s->mode_8bit) {
s->frame->palette_has_changed = ff_copy_palette(s->pal, avpkt, avctx);
}
if (s->mode_8bit)
msvideo1_decode_8bit(s);
else
msvideo1_decode_16bit(s);
if ((ret = av_frame_ref(rframe, s->frame)) < 0)
return ret;
*got_frame = 1;
/* report that the buffer was completely consumed */
return buf_size;
}
static av_cold int msvideo1_decode_end(AVCodecContext *avctx)
{
Msvideo1Context *s = avctx->priv_data;
av_frame_free(&s->frame);
return 0;
}
const FFCodec ff_msvideo1_decoder = {
.p.name = "msvideo1",
.p.long_name = NULL_IF_CONFIG_SMALL("Microsoft Video 1"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_MSVIDEO1,
.priv_data_size = sizeof(Msvideo1Context),
.init = msvideo1_decode_init,
.close = msvideo1_decode_end,
FF_CODEC_DECODE_CB(msvideo1_decode_frame),
.p.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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