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FFmpeg/libavcodec/msvideo1.c
James Almer 9ea6d2149e avcodec/decode: add a flags parameter to ff_reget_buffer() 
Some decoders may not need a writable buffer in some specific cases, but only
a reference to the existing buffer with updated frame properties instead, for
the purpose of returning duplicate frames. For this, the
FF_REGET_BUFFER_FLAG_READONLY flag is added, which will prevent potential
allocations and buffer copies when they are not needed.

Signed-off-by: James Almer <jamrial@gmail.com>
2019-09-04 10:07:12 -03:00

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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 "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,
void *data, 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) {
int size;
const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, &size);
if (pal && size == AVPALETTE_SIZE) {
memcpy(s->pal, pal, AVPALETTE_SIZE);
s->frame->palette_has_changed = 1;
} else if (pal) {
av_log(avctx, AV_LOG_ERROR, "Palette size %d is wrong\n", size);
}
}
if (s->mode_8bit)
msvideo1_decode_8bit(s);
else
msvideo1_decode_16bit(s);
if ((ret = av_frame_ref(data, 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;
}
AVCodec ff_msvideo1_decoder = {
.name = "msvideo1",
.long_name = NULL_IF_CONFIG_SMALL("Microsoft Video 1"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_MSVIDEO1,
.priv_data_size = sizeof(Msvideo1Context),
.init = msvideo1_decode_init,
.close = msvideo1_decode_end,
.decode = msvideo1_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
};
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