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 
59  frame->pict_type = AV_PICTURE_TYPE_I;
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  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
98 };
tmv_decode_init
static av_cold int tmv_decode_init(AVCodecContext *avctx)
Definition: tmv.c:83
AVCodec
AVCodec.
Definition: codec.h:197
FF_CODEC_CAP_INIT_THREADSAFE
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
ff_cga_palette
const uint32_t ff_cga_palette[16]
Definition: cga_data.c:30
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:365
data
const char data[16]
Definition: mxf.c:142
tmv_decode_frame
static int tmv_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: tmv.c:38
ff_draw_pc_font
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
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
av_cold
#define av_cold
Definition: attributes.h:90
AVPALETTE_SIZE
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
src
#define src
Definition: vp8dsp.c:255
c
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
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1638
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:366
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
cga_data.h
xga_font_data.h
internal.h
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:204
AVCodecContext::height
int height
Definition: avcodec.h:674
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:711
avcodec.h
AV_PIX_FMT_PAL8
@ AV_PIX_FMT_PAL8
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
ret
ret
Definition: filter_design.txt:187
frame
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
Definition: filter_design.txt:264
AVCodecContext
main external API structure.
Definition: avcodec.h:501
ff_tmv_decoder
const AVCodec ff_tmv_decoder
Definition: tmv.c:89
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
avpriv_cga_font
const uint8_t avpriv_cga_font[2048]
Definition: xga_font_data.c:29
AVPacket
This structure stores compressed data.
Definition: packet.h:342
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:674
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
AV_CODEC_ID_TMV
@ AV_CODEC_ID_TMV
Definition: codec_id.h:175