FFmpeg
aura.c
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1 /*
2  * Aura 2 decoder
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Aura 2 decoder
24  */
25 
26 #include "avcodec.h"
27 #include "codec_internal.h"
28 #include "decode.h"
29 #include "libavutil/internal.h"
30 
32 {
33  /* width needs to be divisible by 4 for this codec to work */
34  if (avctx->width & 0x3)
35  return AVERROR(EINVAL);
36  avctx->pix_fmt = AV_PIX_FMT_YUV422P;
37 
38  return 0;
39 }
40 
42  int *got_frame, AVPacket *pkt)
43 {
44  uint8_t *Y, *U, *V;
45  uint8_t val;
46  int x, y, ret;
47  const uint8_t *buf = pkt->data;
48 
49  /* prediction error tables (make it clear that they are signed values) */
50  const int8_t *delta_table = (const int8_t*)buf + 16;
51 
52  if (pkt->size != 48 + avctx->height * avctx->width) {
53  av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
54  pkt->size, 48 + avctx->height * avctx->width);
55  return AVERROR_INVALIDDATA;
56  }
57 
58  /* pixel data starts 48 bytes in, after 3x16-byte tables */
59  buf += 48;
60 
61  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
62  return ret;
63 
64  Y = frame->data[0];
65  U = frame->data[1];
66  V = frame->data[2];
67 
68  /* iterate through each line in the height */
69  for (y = 0; y < avctx->height; y++) {
70  /* reset predictors */
71  val = *buf++;
72  U[0] = val & 0xF0;
73  Y[0] = val << 4;
74  val = *buf++;
75  V[0] = val & 0xF0;
76  Y[1] = Y[0] + delta_table[val & 0xF];
77  Y += 2; U++; V++;
78 
79  /* iterate through the remaining pixel groups (4 pixels/group) */
80  for (x = 1; x < (avctx->width >> 1); x++) {
81  val = *buf++;
82  U[0] = U[-1] + delta_table[val >> 4];
83  Y[0] = Y[-1] + delta_table[val & 0xF];
84  val = *buf++;
85  V[0] = V[-1] + delta_table[val >> 4];
86  Y[1] = Y[ 0] + delta_table[val & 0xF];
87  Y += 2; U++; V++;
88  }
89  Y += frame->linesize[0] - avctx->width;
90  U += frame->linesize[1] - (avctx->width >> 1);
91  V += frame->linesize[2] - (avctx->width >> 1);
92  }
93 
94  *got_frame = 1;
95 
96  return pkt->size;
97 }
98 
100  .p.name = "aura2",
101  CODEC_LONG_NAME("Auravision Aura 2"),
102  .p.type = AVMEDIA_TYPE_VIDEO,
103  .p.id = AV_CODEC_ID_AURA2,
104  .init = aura_decode_init,
106  .p.capabilities = AV_CODEC_CAP_DR1,
107 };
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
aura_decode_frame
static int aura_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
Definition: aura.c:41
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:325
AVPacket::data
uint8_t * data
Definition: packet.h:374
FFCodec
Definition: codec_internal.h:119
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:123
val
static double val(void *priv, double ch)
Definition: aeval.c:77
pkt
AVPacket * pkt
Definition: movenc.c:59
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:298
ff_aura2_decoder
const FFCodec ff_aura2_decoder
Definition: aura.c:99
decode.h
AV_CODEC_ID_AURA2
@ AV_CODEC_ID_AURA2
Definition: codec_id.h:176
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:264
aura_decode_init
static av_cold int aura_decode_init(AVCodecContext *avctx)
Definition: aura.c:31
V
#define V
Definition: avdct.c:30
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1450
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:375
codec_internal.h
Y
#define Y
Definition: boxblur.h:37
internal.h
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:211
AVCodecContext::height
int height
Definition: avcodec.h:571
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:608
avcodec.h
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
U
#define U(x)
Definition: vpx_arith.h:37
AVCodecContext
main external API structure.
Definition: avcodec.h:398
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AV_PIX_FMT_YUV422P
@ AV_PIX_FMT_YUV422P
planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Definition: pixfmt.h:70
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:571
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