FFmpeg
tmv.c
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1 /*
2  * 8088flex TMV video decoder
3  * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * 8088flex TMV video decoder
25  * @author Daniel Verkamp
26  * @see http://www.oldskool.org/pc/8088_Corruption
27  */
28 
29 #include <string.h>
30 
31 #include "avcodec.h"
32 #include "internal.h"
33 #include "libavutil/internal.h"
35 
36 #include "cga_data.h"
37 
38 static int tmv_decode_frame(AVCodecContext *avctx, void *data,
39  int *got_frame, AVPacket *avpkt)
40 {
41  AVFrame *frame = data;
42  const uint8_t *src = avpkt->data;
43  uint8_t *dst;
44  unsigned char_cols = avctx->width >> 3;
45  unsigned char_rows = avctx->height >> 3;
46  unsigned x, y, fg, bg, c;
47  int ret;
48 
49  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
50  return ret;
51 
52  if (avpkt->size < 2*char_rows*char_cols) {
53  av_log(avctx, AV_LOG_ERROR,
54  "Input buffer too small, truncated sample?\n");
55  *got_frame = 0;
56  return AVERROR_INVALIDDATA;
57  }
58 
60  frame->key_frame = 1;
61  dst = frame->data[0];
62 
63  frame->palette_has_changed = 1;
64  memcpy(frame->data[1], ff_cga_palette, 16 * 4);
65  memset(frame->data[1] + 16 * 4, 0, AVPALETTE_SIZE - 16 * 4);
66 
67  for (y = 0; y < char_rows; y++) {
68  for (x = 0; x < char_cols; x++) {
69  c = *src++;
70  bg = *src >> 4;
71  fg = *src++ & 0xF;
72  ff_draw_pc_font(dst + x * 8, frame->linesize[0],
73  avpriv_cga_font, 8, c, fg, bg);
74  }
75  dst += frame->linesize[0] * 8;
76  }
77 
78  *got_frame = 1;
79 
80  return avpkt->size;
81 }
82 
84 {
85  avctx->pix_fmt = AV_PIX_FMT_PAL8;
86  return 0;
87 }
88 
90  .name = "tmv",
91  .long_name = NULL_IF_CONFIG_SMALL("8088flex TMV"),
92  .type = AVMEDIA_TYPE_VIDEO,
93  .id = AV_CODEC_ID_TMV,
94  .init = tmv_decode_init,
95  .decode = tmv_decode_frame,
96  .capabilities = AV_CODEC_CAP_DR1,
97 };
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
int size
Definition: avcodec.h:1481
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1778
#define src
Definition: vp8dsp.c:254
AVCodec.
Definition: avcodec.h:3492
uint8_t
#define av_cold
Definition: attributes.h:82
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
uint8_t * data
Definition: avcodec.h:1480
CGA/EGA/VGA ROM data.
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
const uint8_t avpriv_cga_font[2048]
Definition: xga_font_data.c:29
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
static int tmv_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: tmv.c:38
const char * name
Name of the codec implementation.
Definition: avcodec.h:3499
common internal API header
AVCodec ff_tmv_decoder
Definition: tmv.c:89
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:378
int width
picture width / height.
Definition: avcodec.h:1741
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
void ff_draw_pc_font(uint8_t *dst, int linesize, const uint8_t *font, int font_height, int ch, int fg, int bg)
Draw CGA/EGA/VGA font to 8-bit pixel buffer.
Definition: cga_data.c:46
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:326
main external API structure.
Definition: avcodec.h:1568
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1968
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:452
const uint32_t ff_cga_palette[16]
Definition: cga_data.c:30
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
common internal api header.
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:373
This structure stores compressed data.
Definition: avcodec.h:1457
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:984
CGA/EGA/VGA ROM font data.
static av_cold int tmv_decode_init(AVCodecContext *avctx)
Definition: tmv.c:83