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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-12 19:18:44 +02:00
FFmpeg/libavcodec/mss1.c
Reimar Döffinger cbeaf67888 Avoid using empty macro arguments.
These are not supported by all compilers (gcc 2.95 but also older SPARC
compilers, see gcc bug  for example), and there is no real need for them.
One use of this feature remains in libavdevice/v4l2.c which can't be
replaced quite as easily.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
2013-12-31 12:19:59 +01:00

227 lines
6.0 KiB
C

/*
* Microsoft Screen 1 (aka Windows Media Video V7 Screen) decoder
* Copyright (c) 2012 Konstantin Shishkov
*
* 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 Screen 1 (aka Windows Media Video V7 Screen) decoder
*/
#include "avcodec.h"
#include "internal.h"
#include "mss12.h"
typedef struct MSS1Context {
MSS12Context ctx;
AVFrame *pic;
SliceContext sc;
} MSS1Context;
static void arith_normalise(ArithCoder *c)
{
for (;;) {
if (c->high >= 0x8000) {
if (c->low < 0x8000) {
if (c->low >= 0x4000 && c->high < 0xC000) {
c->value -= 0x4000;
c->low -= 0x4000;
c->high -= 0x4000;
} else {
return;
}
} else {
c->value -= 0x8000;
c->low -= 0x8000;
c->high -= 0x8000;
}
}
c->value <<= 1;
c->low <<= 1;
c->high <<= 1;
c->high |= 1;
c->value |= get_bits1(c->gbc.gb);
}
}
ARITH_GET_BIT(arith)
static int arith_get_bits(ArithCoder *c, int bits)
{
int range = c->high - c->low + 1;
int val = (((c->value - c->low + 1) << bits) - 1) / range;
int prob = range * val;
c->high = ((prob + range) >> bits) + c->low - 1;
c->low += prob >> bits;
arith_normalise(c);
return val;
}
static int arith_get_number(ArithCoder *c, int mod_val)
{
int range = c->high - c->low + 1;
int val = ((c->value - c->low + 1) * mod_val - 1) / range;
int prob = range * val;
c->high = (prob + range) / mod_val + c->low - 1;
c->low += prob / mod_val;
arith_normalise(c);
return val;
}
static int arith_get_prob(ArithCoder *c, int16_t *probs)
{
int range = c->high - c->low + 1;
int val = ((c->value - c->low + 1) * probs[0] - 1) / range;
int sym = 1;
while (probs[sym] > val)
sym++;
c->high = range * probs[sym - 1] / probs[0] + c->low - 1;
c->low += range * probs[sym] / probs[0];
return sym;
}
ARITH_GET_MODEL_SYM(arith)
static void arith_init(ArithCoder *c, GetBitContext *gb)
{
c->low = 0;
c->high = 0xFFFF;
c->value = get_bits(gb, 16);
c->gbc.gb = gb;
c->get_model_sym = arith_get_model_sym;
c->get_number = arith_get_number;
}
static int decode_pal(MSS12Context *ctx, ArithCoder *acoder)
{
int i, ncol, r, g, b;
uint32_t *pal = ctx->pal + 256 - ctx->free_colours;
if (!ctx->free_colours)
return 0;
ncol = arith_get_number(acoder, ctx->free_colours + 1);
for (i = 0; i < ncol; i++) {
r = arith_get_bits(acoder, 8);
g = arith_get_bits(acoder, 8);
b = arith_get_bits(acoder, 8);
*pal++ = (0xFFU << 24) | (r << 16) | (g << 8) | b;
}
return !!ncol;
}
static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *avpkt)
{
MSS1Context *ctx = avctx->priv_data;
MSS12Context *c = &ctx->ctx;
GetBitContext gb;
ArithCoder acoder;
int pal_changed = 0;
int ret;
if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
return ret;
arith_init(&acoder, &gb);
if ((ret = ff_reget_buffer(avctx, ctx->pic)) < 0)
return ret;
c->pal_pic = ctx->pic->data[0] + ctx->pic->linesize[0] * (avctx->height - 1);
c->pal_stride = -ctx->pic->linesize[0];
c->keyframe = !arith_get_bit(&acoder);
if (c->keyframe) {
c->corrupted = 0;
ff_mss12_slicecontext_reset(&ctx->sc);
pal_changed = decode_pal(c, &acoder);
ctx->pic->key_frame = 1;
ctx->pic->pict_type = AV_PICTURE_TYPE_I;
} else {
if (c->corrupted)
return AVERROR_INVALIDDATA;
ctx->pic->key_frame = 0;
ctx->pic->pict_type = AV_PICTURE_TYPE_P;
}
c->corrupted = ff_mss12_decode_rect(&ctx->sc, &acoder, 0, 0,
avctx->width, avctx->height);
if (c->corrupted)
return AVERROR_INVALIDDATA;
memcpy(ctx->pic->data[1], c->pal, AVPALETTE_SIZE);
ctx->pic->palette_has_changed = pal_changed;
if ((ret = av_frame_ref(data, ctx->pic)) < 0)
return ret;
*got_frame = 1;
/* always report that the buffer was completely consumed */
return avpkt->size;
}
static av_cold int mss1_decode_init(AVCodecContext *avctx)
{
MSS1Context * const c = avctx->priv_data;
int ret;
c->ctx.avctx = avctx;
c->pic = av_frame_alloc();
if (!c->pic)
return AVERROR(ENOMEM);
ret = ff_mss12_decode_init(&c->ctx, 0, &c->sc, NULL);
avctx->pix_fmt = AV_PIX_FMT_PAL8;
return ret;
}
static av_cold int mss1_decode_end(AVCodecContext *avctx)
{
MSS1Context * const ctx = avctx->priv_data;
av_frame_free(&ctx->pic);
ff_mss12_decode_end(&ctx->ctx);
return 0;
}
AVCodec ff_mss1_decoder = {
.name = "mss1",
.long_name = NULL_IF_CONFIG_SMALL("MS Screen 1"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_MSS1,
.priv_data_size = sizeof(MSS1Context),
.init = mss1_decode_init,
.close = mss1_decode_end,
.decode = mss1_decode_frame,
.capabilities = CODEC_CAP_DR1,
};