FFmpeg  4.0
Macros | Functions | Variables
h261dec.c File Reference

H.261 decoder. More...

#include "libavutil/avassert.h"
#include "avcodec.h"
#include "mpeg_er.h"
#include "mpegutils.h"
#include "mpegvideo.h"
#include "h263.h"
#include "h261.h"
#include "internal.h"

Go to the source code of this file.

Macros

#define H261_MBA_VLC_BITS   9
 
#define H261_MTYPE_VLC_BITS   6
 
#define H261_MV_VLC_BITS   7
 
#define H261_CBP_VLC_BITS   9
 
#define TCOEFF_VLC_BITS   9
 
#define MBA_STUFFING   33
 
#define MBA_STARTCODE   34
 

Functions

static av_cold void h261_decode_init_vlc (H261Context *h)
 
static av_cold int h261_decode_init (AVCodecContext *avctx)
 
static int h261_decode_gob_header (H261Context *h)
 Decode the group of blocks header or slice header. More...
 
static int h261_resync (H261Context *h)
 Decode the group of blocks / video packet header. More...
 
static int h261_decode_mb_skipped (H261Context *h, int mba1, int mba2)
 Decode skipped macroblocks. More...
 
static int decode_mv_component (GetBitContext *gb, int v)
 
static int h261_decode_block (H261Context *h, int16_t *block, int n, int coded)
 Decode a macroblock. More...
 
static int h261_decode_mb (H261Context *h)
 
static int h261_decode_picture_header (H261Context *h)
 Decode the H.261 picture header. More...
 
static int h261_decode_gob (H261Context *h)
 
static int get_consumed_bytes (MpegEncContext *s, int buf_size)
 returns the number of bytes consumed for building the current frame More...
 
static int h261_decode_frame (AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
 
static av_cold int h261_decode_end (AVCodecContext *avctx)
 

Variables

static VLC h261_mba_vlc
 
static VLC h261_mtype_vlc
 
static VLC h261_mv_vlc
 
static VLC h261_cbp_vlc
 
static const int mvmap [17]
 
AVCodec ff_h261_decoder
 

Detailed Description

H.261 decoder.

Definition in file h261dec.c.

Macro Definition Documentation

◆ H261_MBA_VLC_BITS

#define H261_MBA_VLC_BITS   9

Definition at line 37 of file h261dec.c.

Referenced by h261_decode_init_vlc(), and h261_decode_mb().

◆ H261_MTYPE_VLC_BITS

#define H261_MTYPE_VLC_BITS   6

Definition at line 38 of file h261dec.c.

Referenced by h261_decode_init_vlc(), and h261_decode_mb().

◆ H261_MV_VLC_BITS

#define H261_MV_VLC_BITS   7

Definition at line 39 of file h261dec.c.

Referenced by decode_mv_component(), and h261_decode_init_vlc().

◆ H261_CBP_VLC_BITS

#define H261_CBP_VLC_BITS   9

Definition at line 40 of file h261dec.c.

Referenced by h261_decode_init_vlc(), and h261_decode_mb().

◆ TCOEFF_VLC_BITS

#define TCOEFF_VLC_BITS   9

Definition at line 41 of file h261dec.c.

Referenced by h261_decode_block().

◆ MBA_STUFFING

#define MBA_STUFFING   33

Definition at line 42 of file h261dec.c.

Referenced by h261_decode_gob(), and h261_decode_mb().

◆ MBA_STARTCODE

#define MBA_STARTCODE   34

Definition at line 43 of file h261dec.c.

Referenced by h261_decode_mb().

Function Documentation

◆ h261_decode_init_vlc()

static av_cold void h261_decode_init_vlc ( H261Context *  h)
static

Definition at line 50 of file h261dec.c.

Referenced by h261_decode_init().

◆ h261_decode_init()

static av_cold int h261_decode_init ( AVCodecContext *  avctx)
static

Definition at line 72 of file h261dec.c.

◆ h261_decode_gob_header()

static int h261_decode_gob_header ( H261Context *  h)
static

Decode the group of blocks header or slice header.

Returns
<0 if an error occurred

Definition at line 97 of file h261dec.c.

Referenced by h261_resync().

◆ h261_resync()

static int h261_resync ( H261Context *  h)
static

Decode the group of blocks / video packet header.

Returns
<0 if no resync found

Definition at line 151 of file h261dec.c.

Referenced by h261_decode_frame().

◆ h261_decode_mb_skipped()

static int h261_decode_mb_skipped ( H261Context *  h,
int  mba1,
int  mba2 
)
static

Decode skipped macroblocks.

Returns
0

Definition at line 192 of file h261dec.c.

Referenced by h261_decode_gob().

◆ decode_mv_component()

static int decode_mv_component ( GetBitContext *  gb,
int  v 
)
static

Definition at line 236 of file h261dec.c.

Referenced by h261_decode_mb().

◆ h261_decode_block()

static int h261_decode_block ( H261Context *  h,
int16_t *  block,
int  n,
int  coded 
)
static

Decode a macroblock.

Returns
<0 if an error occurred

Definition at line 262 of file h261dec.c.

Referenced by h261_decode_mb().

◆ h261_decode_mb()

static int h261_decode_mb ( H261Context *  h)
static

Definition at line 354 of file h261dec.c.

Referenced by h261_decode_gob().

◆ h261_decode_picture_header()

static int h261_decode_picture_header ( H261Context *  h)
static

Decode the H.261 picture header.

Returns
<0 if no startcode found

Definition at line 478 of file h261dec.c.

Referenced by h261_decode_frame().

◆ h261_decode_gob()

static int h261_decode_gob ( H261Context *  h)
static

Definition at line 542 of file h261dec.c.

Referenced by h261_decode_frame().

◆ get_consumed_bytes()

static int get_consumed_bytes ( MpegEncContext *  s,
int  buf_size 
)
static

returns the number of bytes consumed for building the current frame

Definition at line 574 of file h261dec.c.

Referenced by h261_decode_frame().

◆ h261_decode_frame()

static int h261_decode_frame ( AVCodecContext *  avctx,
void *  data,
int *  got_frame,
AVPacket *  avpkt 
)
static

Definition at line 585 of file h261dec.c.

◆ h261_decode_end()

static av_cold int h261_decode_end ( AVCodecContext *  avctx)
static

Definition at line 670 of file h261dec.c.

Variable Documentation

◆ h261_mba_vlc

VLC h261_mba_vlc
static

Definition at line 45 of file h261dec.c.

◆ h261_mtype_vlc

VLC h261_mtype_vlc
static

Definition at line 46 of file h261dec.c.

◆ h261_mv_vlc

VLC h261_mv_vlc
static

Definition at line 47 of file h261dec.c.

◆ h261_cbp_vlc

VLC h261_cbp_vlc
static

Definition at line 48 of file h261dec.c.

◆ mvmap

const int mvmap[17]
static
Initial value:
= {
0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16
}

Definition at line 232 of file h261dec.c.

Referenced by decode_mv_component().

◆ ff_h261_decoder

AVCodec ff_h261_decoder
Initial value:
= {
.name = "h261",
.long_name = NULL_IF_CONFIG_SMALL("H.261"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_H261,
.priv_data_size = sizeof(H261Context),
.init = h261_decode_init,
.close = h261_decode_end,
.decode = h261_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.max_lowres = 3,
}
init
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
H261Context
H261Context.
Definition: h261.h:37
decode
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:42
h261_decode_frame
static int h261_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: h261dec.c:585
AV_CODEC_ID_H261
Definition: avcodec.h:221
h261_decode_init
static av_cold int h261_decode_init(AVCodecContext *avctx)
Definition: h261dec.c:72
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:186
h261_decode_end
static av_cold int h261_decode_end(AVCodecContext *avctx)
Definition: h261dec.c:670
AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:959

Definition at line 679 of file h261dec.c.

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