FFmpeg
flvdec.c
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1 /*
2  * FLV decoding.
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 #include "libavutil/imgutils.h"
22 
23 #include "flv.h"
24 #include "h263.h"
25 #include "mpegvideo.h"
26 #include "mpegvideodata.h"
27 
29 {
30  int format, width, height;
31 
32  /* picture header */
33  if (get_bits_long(&s->gb, 17) != 1) {
34  av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
35  return AVERROR_INVALIDDATA;
36  }
37  format = get_bits(&s->gb, 5);
38  if (format != 0 && format != 1) {
39  av_log(s->avctx, AV_LOG_ERROR, "Bad picture format\n");
40  return AVERROR_INVALIDDATA;
41  }
42  s->h263_flv = format + 1;
43  s->picture_number = get_bits(&s->gb, 8); /* picture timestamp */
44  format = get_bits(&s->gb, 3);
45  switch (format) {
46  case 0:
47  width = get_bits(&s->gb, 8);
48  height = get_bits(&s->gb, 8);
49  break;
50  case 1:
51  width = get_bits(&s->gb, 16);
52  height = get_bits(&s->gb, 16);
53  break;
54  case 2:
55  width = 352;
56  height = 288;
57  break;
58  case 3:
59  width = 176;
60  height = 144;
61  break;
62  case 4:
63  width = 128;
64  height = 96;
65  break;
66  case 5:
67  width = 320;
68  height = 240;
69  break;
70  case 6:
71  width = 160;
72  height = 120;
73  break;
74  default:
75  width = height = 0;
76  break;
77  }
78  if (av_image_check_size(width, height, 0, s->avctx))
79  return AVERROR(EINVAL);
80  s->width = width;
81  s->height = height;
82 
83  s->pict_type = AV_PICTURE_TYPE_I + get_bits(&s->gb, 2);
85  if (s->droppable)
87 
88  skip_bits1(&s->gb); /* deblocking flag */
89  s->chroma_qscale = s->qscale = get_bits(&s->gb, 5);
90 
91  s->h263_plus = 0;
92 
93  s->unrestricted_mv = 1;
94  s->h263_long_vectors = 0;
95 
96  /* PEI */
97  if (skip_1stop_8data_bits(&s->gb) < 0)
98  return AVERROR_INVALIDDATA;
99 
100  s->f_code = 1;
101 
102  if (s->ehc_mode)
104 
105  if (s->avctx->debug & FF_DEBUG_PICT_INFO) {
106  av_log(s->avctx, AV_LOG_DEBUG, "%c esc_type:%d, qp:%d num:%d\n",
108  s->h263_flv - 1, s->qscale, s->picture_number);
109  }
110 
112 
113  return 0;
114 }
115 
117  .name = "flv",
118  .long_name = NULL_IF_CONFIG_SMALL("FLV / Sorenson Spark / Sorenson H.263 (Flash Video)"),
119  .type = AVMEDIA_TYPE_VIDEO,
120  .id = AV_CODEC_ID_FLV1,
121  .priv_data_size = sizeof(MpegEncContext),
123  .close = ff_h263_decode_end,
126  .caps_internal = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,
127  .max_lowres = 3,
128  .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,
129  AV_PIX_FMT_NONE },
130 };
int picture_number
Definition: mpegvideo.h:127
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
const uint8_t * y_dc_scale_table
qscale -> y_dc_scale table
Definition: mpegvideo.h:188
misc image utilities
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
AVRational sample_aspect_ratio
sample aspect ratio (0 if unknown) That is the width of a pixel divided by the height of the pixel...
Definition: avcodec.h:1944
mpegvideo header.
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 format(the sample packing is implied by the sample format) and sample rate.The lists are not just lists
AVCodec.
Definition: avcodec.h:3477
int qscale
QP.
Definition: mpegvideo.h:204
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:42
const uint8_t ff_mpeg1_dc_scale_table[128]
Definition: mpegvideodata.c:34
#define FF_DEBUG_PICT_INFO
Definition: avcodec.h:2647
#define height
char av_get_picture_type_char(enum AVPictureType pict_type)
Return a single letter to describe the given picture type pict_type.
Definition: utils.c:88
#define av_log(a,...)
int h263_plus
H.263+ headers.
Definition: mpegvideo.h:109
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVCodec ff_flv_decoder
Definition: flvdec.c:116
int unrestricted_mv
mv can point outside of the coded picture
Definition: mpegvideo.h:223
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
const char * name
Name of the codec implementation.
Definition: avcodec.h:3484
GetBitContext gb
Definition: mpegvideo.h:448
int ff_h263_decode_init(AVCodecContext *avctx)
Definition: h263dec.c:68
int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx)
Check if the given dimension of an image is valid, meaning that all bytes of the image can be address...
Definition: imgutils.c:282
int ff_h263_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: h263dec.c:421
#define AV_CODEC_CAP_DRAW_HORIZ_BAND
Decoder can use draw_horiz_band callback.
Definition: avcodec.h:975
#define width
#define s(width, name)
Definition: cbs_vp9.c:257
int h263_flv
use flv H.263 header
Definition: mpegvideo.h:110
int debug
debug
Definition: avcodec.h:2646
int height
picture size. must be a multiple of 16
Definition: mpegvideo.h:100
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:538
Rational number (pair of numerator and denominator).
Definition: rational.h:58
int f_code
forward MV resolution
Definition: mpegvideo.h:238
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:546
int pict_type
AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_P, AV_PICTURE_TYPE_B, ...
Definition: mpegvideo.h:212
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:275
const uint8_t * c_dc_scale_table
qscale -> c_dc_scale table
Definition: mpegvideo.h:189
MpegEncContext.
Definition: mpegvideo.h:81
struct AVCodecContext * avctx
Definition: mpegvideo.h:98
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
#define FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM
The decoder extracts and fills its parameters even if the frame is skipped due to the skip_frame sett...
Definition: internal.h:60
int ff_h263_decode_end(AVCodecContext *avctx)
Definition: h263dec.c:155
int chroma_qscale
chroma QP
Definition: mpegvideo.h:205
static int skip_1stop_8data_bits(GetBitContext *gb)
Definition: get_bits.h:854
int ff_flv_decode_picture_header(MpegEncContext *s)
Definition: flvdec.c:28
int h263_long_vectors
use horrible H.263v1 long vector mode
Definition: mpegvideo.h:224
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
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:981
Predicted.
Definition: avutil.h:275