FFmpeg
vcr1.c
Go to the documentation of this file.
1 /*
2  * ATI VCR1 codec
3  * Copyright (c) 2003 Michael Niedermayer
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  * ATI VCR1 codec
25  */
26 
27 #include "avcodec.h"
28 #include "codec_internal.h"
29 #include "decode.h"
30 #include "libavutil/avassert.h"
31 #include "libavutil/internal.h"
32 
33 typedef struct VCR1Context {
34  int delta[16];
35  int offset[4];
36 } VCR1Context;
37 
39 {
40  avctx->pix_fmt = AV_PIX_FMT_YUV410P;
41 
42  if (avctx->width % 8 || avctx->height%4) {
43  avpriv_request_sample(avctx, "odd dimensions (%d x %d) support", avctx->width, avctx->height);
44  return AVERROR_INVALIDDATA;
45  }
46 
47  return 0;
48 }
49 
51  int *got_frame, AVPacket *avpkt)
52 {
53  VCR1Context *const a = avctx->priv_data;
54  const uint8_t *bytestream = avpkt->data;
55  const uint8_t *bytestream_end = bytestream + avpkt->size;
56  int i, x, y, ret;
57 
58  if(avpkt->size < 32 + avctx->height + avctx->width*avctx->height*5/8){
59  av_log(avctx, AV_LOG_ERROR, "Insufficient input data. %d < %d\n", avpkt->size , 32 + avctx->height + avctx->width*avctx->height*5/8);
60  return AVERROR(EINVAL);
61  }
62 
63  if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
64  return ret;
65 
66  for (i = 0; i < 16; i++) {
67  a->delta[i] = *bytestream++;
68  bytestream++;
69  }
70 
71  for (y = 0; y < avctx->height; y++) {
72  int offset;
73  uint8_t *luma = &p->data[0][y * p->linesize[0]];
74 
75  if ((y & 3) == 0) {
76  uint8_t *cb = &p->data[1][(y >> 2) * p->linesize[1]];
77  uint8_t *cr = &p->data[2][(y >> 2) * p->linesize[2]];
78 
79  av_assert0 (bytestream_end - bytestream >= 4 + avctx->width);
80 
81  for (i = 0; i < 4; i++)
82  a->offset[i] = *bytestream++;
83 
84  offset = a->offset[0] - a->delta[bytestream[2] & 0xF];
85  for (x = 0; x < avctx->width; x += 4) {
86  luma[0] = offset += a->delta[bytestream[2] & 0xF];
87  luma[1] = offset += a->delta[bytestream[2] >> 4];
88  luma[2] = offset += a->delta[bytestream[0] & 0xF];
89  luma[3] = offset += a->delta[bytestream[0] >> 4];
90  luma += 4;
91 
92  *cb++ = bytestream[3];
93  *cr++ = bytestream[1];
94 
95  bytestream += 4;
96  }
97  } else {
98  av_assert0 (bytestream_end - bytestream >= avctx->width / 2);
99 
100  offset = a->offset[y & 3] - a->delta[bytestream[2] & 0xF];
101 
102  for (x = 0; x < avctx->width; x += 8) {
103  luma[0] = offset += a->delta[bytestream[2] & 0xF];
104  luma[1] = offset += a->delta[bytestream[2] >> 4];
105  luma[2] = offset += a->delta[bytestream[3] & 0xF];
106  luma[3] = offset += a->delta[bytestream[3] >> 4];
107  luma[4] = offset += a->delta[bytestream[0] & 0xF];
108  luma[5] = offset += a->delta[bytestream[0] >> 4];
109  luma[6] = offset += a->delta[bytestream[1] & 0xF];
110  luma[7] = offset += a->delta[bytestream[1] >> 4];
111  luma += 8;
112  bytestream += 4;
113  }
114  }
115  }
116 
117  *got_frame = 1;
118 
119  return bytestream - avpkt->data;
120 }
121 
123  .p.name = "vcr1",
124  CODEC_LONG_NAME("ATI VCR1"),
125  .p.type = AVMEDIA_TYPE_VIDEO,
126  .p.id = AV_CODEC_ID_VCR1,
127  .priv_data_size = sizeof(VCR1Context),
130  .p.capabilities = AV_CODEC_CAP_DR1,
131 };
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
cb
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:246
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:374
AVPacket::data
uint8_t * data
Definition: packet.h:520
FFCodec
Definition: codec_internal.h:126
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:395
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:130
VCR1Context
Definition: vcr1.c:33
avassert.h
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
av_cold
#define av_cold
Definition: attributes.h:90
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:286
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:40
decode.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:271
AV_CODEC_ID_VCR1
@ AV_CODEC_ID_VCR1
Definition: codec_id.h:87
vcr1_decode_frame
static int vcr1_decode_frame(AVCodecContext *avctx, AVFrame *p, int *got_frame, AVPacket *avpkt)
Definition: vcr1.c:50
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1575
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:366
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:521
codec_internal.h
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
VCR1Context::offset
int offset[4]
Definition: vcr1.c:35
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
ff_vcr1_decoder
const FFCodec ff_vcr1_decoder
Definition: vcr1.c:122
offset
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
Definition: writing_filters.txt:86
VCR1Context::delta
int delta[16]
Definition: vcr1.c:34
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
internal.h
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
AVCodecContext::height
int height
Definition: avcodec.h:618
vcr1_decode_init
static av_cold int vcr1_decode_init(AVCodecContext *avctx)
Definition: vcr1.c:38
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:657
avcodec.h
ret
ret
Definition: filter_design.txt:187
AVCodecContext
main external API structure.
Definition: avcodec.h:445
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:36
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
AVPacket
This structure stores compressed data.
Definition: packet.h:497
cr
static double cr(void *priv, double x, double y)
Definition: vf_geq.c:247
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:618
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, a positive or negative value, which is typically indicating the size in bytes of each pict...
Definition: frame.h:419
AV_PIX_FMT_YUV410P
@ AV_PIX_FMT_YUV410P
planar YUV 4:1:0, 9bpp, (1 Cr & Cb sample per 4x4 Y samples)
Definition: pixfmt.h:79
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61