FFmpeg
yuv4dec.c
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1 /*
2  * libquicktime yuv4 decoder
3  *
4  * Copyright (c) 2011 Carl Eugen Hoyos
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "avcodec.h"
24 #include "codec_internal.h"
25 #include "decode.h"
26 
28 {
29  avctx->pix_fmt = AV_PIX_FMT_YUV420P;
30 
31  return 0;
32 }
33 
34 static int yuv4_decode_frame(AVCodecContext *avctx, AVFrame *pic,
35  int *got_frame, AVPacket *avpkt)
36 {
37  const uint8_t *src = avpkt->data;
38  uint8_t *y, *u, *v;
39  int i, j, ret;
40 
41  if (avpkt->size < 6 * (avctx->width + 1 >> 1) * (avctx->height + 1 >> 1)) {
42  av_log(avctx, AV_LOG_ERROR, "Insufficient input data.\n");
43  return AVERROR(EINVAL);
44  }
45 
46  if ((ret = ff_get_buffer(avctx, pic, 0)) < 0)
47  return ret;
48 
49  y = pic->data[0];
50  u = pic->data[1];
51  v = pic->data[2];
52 
53  for (i = 0; i < (avctx->height + 1) >> 1; i++) {
54  for (j = 0; j < (avctx->width + 1) >> 1; j++) {
55  u[j] = *src++ ^ 0x80;
56  v[j] = *src++ ^ 0x80;
57  y[ 2 * j ] = *src++;
58  y[ 2 * j + 1] = *src++;
59  y[pic->linesize[0] + 2 * j ] = *src++;
60  y[pic->linesize[0] + 2 * j + 1] = *src++;
61  }
62 
63  y += 2 * pic->linesize[0];
64  u += pic->linesize[1];
65  v += pic->linesize[2];
66  }
67 
68  *got_frame = 1;
69 
70  return avpkt->size;
71 }
72 
74  .p.name = "yuv4",
75  CODEC_LONG_NAME("Uncompressed packed 4:2:0"),
76  .p.type = AVMEDIA_TYPE_VIDEO,
77  .p.id = AV_CODEC_ID_YUV4,
78  .init = yuv4_decode_init,
80  .p.capabilities = AV_CODEC_CAP_DR1,
81 };
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
u
#define u(width, name, range_min, range_max)
Definition: cbs_h2645.c:251
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:374
ff_yuv4_decoder
const FFCodec ff_yuv4_decoder
Definition: yuv4dec.c:73
AVPacket::data
uint8_t * data
Definition: packet.h:524
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
AV_CODEC_ID_YUV4
@ AV_CODEC_ID_YUV4
Definition: codec_id.h:259
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
decode.h
AV_PIX_FMT_YUV420P
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:73
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:271
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1575
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:525
codec_internal.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
AVCodecContext::height
int height
Definition: avcodec.h:618
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
yuv4_decode_frame
static int yuv4_decode_frame(AVCodecContext *avctx, AVFrame *pic, int *got_frame, AVPacket *avpkt)
Definition: yuv4dec.c:34
AVPacket
This structure stores compressed data.
Definition: packet.h:501
src
INIT_CLIP pixel * src
Definition: h264pred_template.c:418
yuv4_decode_init
static av_cold int yuv4_decode_init(AVCodecContext *avctx)
Definition: yuv4dec.c:27
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_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27