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FFmpeg/libavcodec/bmp.c
Michael Niedermayer aec340c533 avcodec/bmp: Analyze BGRA files alpha channel to choose pixel format 
BGRA BMPs commonly do contain an all transparent alpha channel

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2015-09-10 16:36:47 +02:00

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/*
* BMP image format decoder
* Copyright (c) 2005 Mans Rullgard
*
* 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 <inttypes.h>
#include "avcodec.h"
#include "bytestream.h"
#include "bmp.h"
#include "internal.h"
#include "msrledec.h"
static int bmp_decode_frame(AVCodecContext *avctx,
void *data, int *got_frame,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
AVFrame *p = data;
unsigned int fsize, hsize;
int width, height;
unsigned int depth;
BiCompression comp;
unsigned int ihsize;
int i, j, n, linesize, ret;
uint32_t rgb[3] = {0};
uint32_t alpha = 0;
uint8_t *ptr;
int dsize;
const uint8_t *buf0 = buf;
GetByteContext gb;
if (buf_size < 14) {
av_log(avctx, AV_LOG_ERROR, "buf size too small (%d)\n", buf_size);
return AVERROR_INVALIDDATA;
}
if (bytestream_get_byte(&buf) != 'B' ||
bytestream_get_byte(&buf) != 'M') {
av_log(avctx, AV_LOG_ERROR, "bad magic number\n");
return AVERROR_INVALIDDATA;
}
fsize = bytestream_get_le32(&buf);
if (buf_size < fsize) {
av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %u), trying to decode anyway\n",
buf_size, fsize);
fsize = buf_size;
}
buf += 2; /* reserved1 */
buf += 2; /* reserved2 */
hsize = bytestream_get_le32(&buf); /* header size */
ihsize = bytestream_get_le32(&buf); /* more header size */
if (ihsize + 14LL > hsize) {
av_log(avctx, AV_LOG_ERROR, "invalid header size %u\n", hsize);
return AVERROR_INVALIDDATA;
}
/* sometimes file size is set to some headers size, set a real size in that case */
if (fsize == 14 || fsize == ihsize + 14)
fsize = buf_size - 2;
if (fsize <= hsize) {
av_log(avctx, AV_LOG_ERROR,
"Declared file size is less than header size (%u < %u)\n",
fsize, hsize);
return AVERROR_INVALIDDATA;
}
switch (ihsize) {
case 40: // windib
case 56: // windib v3
case 64: // OS/2 v2
case 108: // windib v4
case 124: // windib v5
width = bytestream_get_le32(&buf);
height = bytestream_get_le32(&buf);
break;
case 12: // OS/2 v1
width = bytestream_get_le16(&buf);
height = bytestream_get_le16(&buf);
break;
default:
av_log(avctx, AV_LOG_ERROR, "unsupported BMP file, patch welcome\n");
return AVERROR_PATCHWELCOME;
}
/* planes */
if (bytestream_get_le16(&buf) != 1) {
av_log(avctx, AV_LOG_ERROR, "invalid BMP header\n");
return AVERROR_INVALIDDATA;
}
depth = bytestream_get_le16(&buf);
if (ihsize >= 40)
comp = bytestream_get_le32(&buf);
else
comp = BMP_RGB;
if (comp != BMP_RGB && comp != BMP_BITFIELDS && comp != BMP_RLE4 &&
comp != BMP_RLE8) {
av_log(avctx, AV_LOG_ERROR, "BMP coding %d not supported\n", comp);
return AVERROR_INVALIDDATA;
}
if (comp == BMP_BITFIELDS) {
buf += 20;
rgb[0] = bytestream_get_le32(&buf);
rgb[1] = bytestream_get_le32(&buf);
rgb[2] = bytestream_get_le32(&buf);
if (ihsize > 40)
alpha = bytestream_get_le32(&buf);
}
avctx->width = width;
avctx->height = height > 0 ? height : -height;
avctx->pix_fmt = AV_PIX_FMT_NONE;
switch (depth) {
case 32:
if (comp == BMP_BITFIELDS) {
if (rgb[0] == 0xFF000000 && rgb[1] == 0x00FF0000 && rgb[2] == 0x0000FF00)
avctx->pix_fmt = alpha ? AV_PIX_FMT_ABGR : AV_PIX_FMT_0BGR;
else if (rgb[0] == 0x00FF0000 && rgb[1] == 0x0000FF00 && rgb[2] == 0x000000FF)
avctx->pix_fmt = alpha ? AV_PIX_FMT_BGRA : AV_PIX_FMT_BGR0;
else if (rgb[0] == 0x0000FF00 && rgb[1] == 0x00FF0000 && rgb[2] == 0xFF000000)
avctx->pix_fmt = alpha ? AV_PIX_FMT_ARGB : AV_PIX_FMT_0RGB;
else if (rgb[0] == 0x000000FF && rgb[1] == 0x0000FF00 && rgb[2] == 0x00FF0000)
avctx->pix_fmt = alpha ? AV_PIX_FMT_RGBA : AV_PIX_FMT_RGB0;
else {
av_log(avctx, AV_LOG_ERROR, "Unknown bitfields %0X %0X %0X\n", rgb[0], rgb[1], rgb[2]);
return AVERROR(EINVAL);
}
} else {
avctx->pix_fmt = AV_PIX_FMT_BGRA;
}
break;
case 24:
avctx->pix_fmt = AV_PIX_FMT_BGR24;
break;
case 16:
if (comp == BMP_RGB)
avctx->pix_fmt = AV_PIX_FMT_RGB555;
else if (comp == BMP_BITFIELDS) {
if (rgb[0] == 0xF800 && rgb[1] == 0x07E0 && rgb[2] == 0x001F)
avctx->pix_fmt = AV_PIX_FMT_RGB565;
else if (rgb[0] == 0x7C00 && rgb[1] == 0x03E0 && rgb[2] == 0x001F)
avctx->pix_fmt = AV_PIX_FMT_RGB555;
else if (rgb[0] == 0x0F00 && rgb[1] == 0x00F0 && rgb[2] == 0x000F)
avctx->pix_fmt = AV_PIX_FMT_RGB444;
else {
av_log(avctx, AV_LOG_ERROR,
"Unknown bitfields %0"PRIX32" %0"PRIX32" %0"PRIX32"\n",
rgb[0], rgb[1], rgb[2]);
return AVERROR(EINVAL);
}
}
break;
case 8:
if (hsize - ihsize - 14 > 0)
avctx->pix_fmt = AV_PIX_FMT_PAL8;
else
avctx->pix_fmt = AV_PIX_FMT_GRAY8;
break;
case 1:
case 4:
if (hsize - ihsize - 14 > 0) {
avctx->pix_fmt = AV_PIX_FMT_PAL8;
} else {
av_log(avctx, AV_LOG_ERROR, "Unknown palette for %u-colour BMP\n",
1 << depth);
return AVERROR_INVALIDDATA;
}
break;
default:
av_log(avctx, AV_LOG_ERROR, "depth %u not supported\n", depth);
return AVERROR_INVALIDDATA;
}
if (avctx->pix_fmt == AV_PIX_FMT_NONE) {
av_log(avctx, AV_LOG_ERROR, "unsupported pixel format\n");
return AVERROR_INVALIDDATA;
}
if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
return ret;
p->pict_type = AV_PICTURE_TYPE_I;
p->key_frame = 1;
buf = buf0 + hsize;
dsize = buf_size - hsize;
/* Line size in file multiple of 4 */
n = ((avctx->width * depth + 31) / 8) & ~3;
if (n * avctx->height > dsize && comp != BMP_RLE4 && comp != BMP_RLE8) {
n = (avctx->width * depth + 7) / 8;
if (n * avctx->height > dsize) {
av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %d)\n",
dsize, n * avctx->height);
return AVERROR_INVALIDDATA;
}
av_log(avctx, AV_LOG_ERROR, "data size too small, assuming missing line alignment\n");
}
// RLE may skip decoding some picture areas, so blank picture before decoding
if (comp == BMP_RLE4 || comp == BMP_RLE8)
memset(p->data[0], 0, avctx->height * p->linesize[0]);
if (height > 0) {
ptr = p->data[0] + (avctx->height - 1) * p->linesize[0];
linesize = -p->linesize[0];
} else {
ptr = p->data[0];
linesize = p->linesize[0];
}
if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
int colors = 1 << depth;
memset(p->data[1], 0, 1024);
if (ihsize >= 36) {
int t;
buf = buf0 + 46;
t = bytestream_get_le32(&buf);
if (t < 0 || t > (1 << depth)) {
av_log(avctx, AV_LOG_ERROR,
"Incorrect number of colors - %X for bitdepth %u\n",
t, depth);
} else if (t) {
colors = t;
}
} else {
colors = FFMIN(256, (hsize-ihsize-14) / 3);
}
buf = buf0 + 14 + ihsize; //palette location
// OS/2 bitmap, 3 bytes per palette entry
if ((hsize-ihsize-14) < (colors << 2)) {
if ((hsize-ihsize-14) < colors * 3) {
av_log(avctx, AV_LOG_ERROR, "palette doesn't fit in packet\n");
return AVERROR_INVALIDDATA;
}
for (i = 0; i < colors; i++)
((uint32_t*)p->data[1])[i] = (0xFFU<<24) | bytestream_get_le24(&buf);
} else {
for (i = 0; i < colors; i++)
((uint32_t*)p->data[1])[i] = 0xFFU << 24 | bytestream_get_le32(&buf);
}
buf = buf0 + hsize;
}
if (comp == BMP_RLE4 || comp == BMP_RLE8) {
if (comp == BMP_RLE8 && height < 0) {
p->data[0] += p->linesize[0] * (avctx->height - 1);
p->linesize[0] = -p->linesize[0];
}
bytestream2_init(&gb, buf, dsize);
ff_msrle_decode(avctx, (AVPicture*)p, depth, &gb);
if (height < 0) {
p->data[0] += p->linesize[0] * (avctx->height - 1);
p->linesize[0] = -p->linesize[0];
}
} else {
switch (depth) {
case 1:
for (i = 0; i < avctx->height; i++) {
int j;
for (j = 0; j < n; j++) {
ptr[j*8+0] = buf[j] >> 7;
ptr[j*8+1] = (buf[j] >> 6) & 1;
ptr[j*8+2] = (buf[j] >> 5) & 1;
ptr[j*8+3] = (buf[j] >> 4) & 1;
ptr[j*8+4] = (buf[j] >> 3) & 1;
ptr[j*8+5] = (buf[j] >> 2) & 1;
ptr[j*8+6] = (buf[j] >> 1) & 1;
ptr[j*8+7] = buf[j] & 1;
}
buf += n;
ptr += linesize;
}
break;
case 8:
case 24:
case 32:
for (i = 0; i < avctx->height; i++) {
memcpy(ptr, buf, n);
buf += n;
ptr += linesize;
}
break;
case 4:
for (i = 0; i < avctx->height; i++) {
int j;
for (j = 0; j < n; j++) {
ptr[j*2+0] = (buf[j] >> 4) & 0xF;
ptr[j*2+1] = buf[j] & 0xF;
}
buf += n;
ptr += linesize;
}
break;
case 16:
for (i = 0; i < avctx->height; i++) {
const uint16_t *src = (const uint16_t *) buf;
uint16_t *dst = (uint16_t *) ptr;
for (j = 0; j < avctx->width; j++)
*dst++ = av_le2ne16(*src++);
buf += n;
ptr += linesize;
}
break;
default:
av_log(avctx, AV_LOG_ERROR, "BMP decoder is broken\n");
return AVERROR_INVALIDDATA;
}
}
if (avctx->pix_fmt == AV_PIX_FMT_BGRA) {
for (i = 0; i < avctx->height; i++) {
int j;
uint8_t *ptr = p->data[0] + p->linesize[0]*i + 3;
for (j = 0; j < avctx->width; j++) {
if (ptr[4*j])
break;
}
if (j < avctx->width)
break;
}
if (i == avctx->height)
avctx->pix_fmt = p->format = AV_PIX_FMT_BGR0;
}
*got_frame = 1;
return buf_size;
}
AVCodec ff_bmp_decoder = {
.name = "bmp",
.long_name = NULL_IF_CONFIG_SMALL("BMP (Windows and OS/2 bitmap)"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_BMP,
.decode = bmp_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
};
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